[sql] Import reference version of SQLite 3.17..

third_party/sqlite/sqlite-src-3170000/src/vdbeaux.c

+/*
+** 2003 September 6
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This file contains code used for creating, destroying, and populating
+** a VDBE (or an "sqlite3_stmt" as it is known to the outside world.) 
+*/
+#include "sqliteInt.h"
+#include "vdbeInt.h"
+
+/*
+** Create a new virtual database engine.
+*/
+Vdbe *sqlite3VdbeCreate(Parse *pParse){
+  sqlite3 *db = pParse->db;
+  Vdbe *p;
+  p = sqlite3DbMallocRawNN(db, sizeof(Vdbe) );
+  if( p==0 ) return 0;
+  memset(&p->aOp, 0, sizeof(Vdbe)-offsetof(Vdbe,aOp));
+  p->db = db;
+  if( db->pVdbe ){
+    db->pVdbe->pPrev = p;
+  }
+  p->pNext = db->pVdbe;
+  p->pPrev = 0;
+  db->pVdbe = p;
+  p->magic = VDBE_MAGIC_INIT;
+  p->pParse = pParse;
+  assert( pParse->aLabel==0 );
+  assert( pParse->nLabel==0 );
+  assert( pParse->nOpAlloc==0 );
+  assert( pParse->szOpAlloc==0 );
+  return p;
+}
+
+/*
+** Change the error string stored in Vdbe.zErrMsg
+*/
+void sqlite3VdbeError(Vdbe *p, const char *zFormat, ...){
+  va_list ap;
+  sqlite3DbFree(p->db, p->zErrMsg);
+  va_start(ap, zFormat);
+  p->zErrMsg = sqlite3VMPrintf(p->db, zFormat, ap);
+  va_end(ap);
+}
+
+/*
+** Remember the SQL string for a prepared statement.
+*/
+void sqlite3VdbeSetSql(Vdbe *p, const char *z, int n, int isPrepareV2){
+  assert( isPrepareV2==1 || isPrepareV2==0 );
+  if( p==0 ) return;
+#if defined(SQLITE_OMIT_TRACE) && !defined(SQLITE_ENABLE_SQLLOG)
+  if( !isPrepareV2 ) return;
+#endif
+  assert( p->zSql==0 );
+  p->zSql = sqlite3DbStrNDup(p->db, z, n);
+  p->isPrepareV2 = (u8)isPrepareV2;
+}
+
+/*
+** Swap all content between two VDBE structures.
+*/
+void sqlite3VdbeSwap(Vdbe *pA, Vdbe *pB){
+  Vdbe tmp, *pTmp;
+  char *zTmp;
+  assert( pA->db==pB->db );
+  tmp = *pA;
+  *pA = *pB;
+  *pB = tmp;
+  pTmp = pA->pNext;
+  pA->pNext = pB->pNext;
+  pB->pNext = pTmp;
+  pTmp = pA->pPrev;
+  pA->pPrev = pB->pPrev;
+  pB->pPrev = pTmp;
+  zTmp = pA->zSql;
+  pA->zSql = pB->zSql;
+  pB->zSql = zTmp;
+  pB->isPrepareV2 = pA->isPrepareV2;
+}
+
+/*
+** Resize the Vdbe.aOp array so that it is at least nOp elements larger 
+** than its current size. nOp is guaranteed to be less than or equal
+** to 1024/sizeof(Op).
+**
+** If an out-of-memory error occurs while resizing the array, return
+** SQLITE_NOMEM. In this case Vdbe.aOp and Parse.nOpAlloc remain 
+** unchanged (this is so that any opcodes already allocated can be 
+** correctly deallocated along with the rest of the Vdbe).
+*/
+static int growOpArray(Vdbe *v, int nOp){
+  VdbeOp *pNew;
+  Parse *p = v->pParse;
+
+  /* The SQLITE_TEST_REALLOC_STRESS compile-time option is designed to force
+  ** more frequent reallocs and hence provide more opportunities for 
+  ** simulated OOM faults.  SQLITE_TEST_REALLOC_STRESS is generally used
+  ** during testing only.  With SQLITE_TEST_REALLOC_STRESS grow the op array
+  ** by the minimum* amount required until the size reaches 512.  Normal
+  ** operation (without SQLITE_TEST_REALLOC_STRESS) is to double the current
+  ** size of the op array or add 1KB of space, whichever is smaller. */
+#ifdef SQLITE_TEST_REALLOC_STRESS
+  int nNew = (p->nOpAlloc>=512 ? p->nOpAlloc*2 : p->nOpAlloc+nOp);
+#else
+  int nNew = (p->nOpAlloc ? p->nOpAlloc*2 : (int)(1024/sizeof(Op)));
+  UNUSED_PARAMETER(nOp);
+#endif
+
+  assert( nOp<=(1024/sizeof(Op)) );
+  assert( nNew>=(p->nOpAlloc+nOp) );
+  pNew = sqlite3DbRealloc(p->db, v->aOp, nNew*sizeof(Op));
+  if( pNew ){
+    p->szOpAlloc = sqlite3DbMallocSize(p->db, pNew);
+    p->nOpAlloc = p->szOpAlloc/sizeof(Op);
+    v->aOp = pNew;
+  }
+  return (pNew ? SQLITE_OK : SQLITE_NOMEM_BKPT);
+}
+
+#ifdef SQLITE_DEBUG
+/* This routine is just a convenient place to set a breakpoint that will
+** fire after each opcode is inserted and displayed using
+** "PRAGMA vdbe_addoptrace=on".
+*/
+static void test_addop_breakpoint(void){
+  static int n = 0;
+  n++;
+}
+#endif
+
+/*
+** Add a new instruction to the list of instructions current in the
+** VDBE.  Return the address of the new instruction.
+**
+** Parameters:
+**
+**    p               Pointer to the VDBE
+**
+**    op              The opcode for this instruction
+**
+**    p1, p2, p3      Operands
+**
+** Use the sqlite3VdbeResolveLabel() function to fix an address and
+** the sqlite3VdbeChangeP4() function to change the value of the P4
+** operand.
+*/
+static SQLITE_NOINLINE int growOp3(Vdbe *p, int op, int p1, int p2, int p3){
+  assert( p->pParse->nOpAlloc<=p->nOp );
+  if( growOpArray(p, 1) ) return 1;
+  assert( p->pParse->nOpAlloc>p->nOp );
+  return sqlite3VdbeAddOp3(p, op, p1, p2, p3);
+}
+int sqlite3VdbeAddOp3(Vdbe *p, int op, int p1, int p2, int p3){
+  int i;
+  VdbeOp *pOp;
+
+  i = p->nOp;
+  assert( p->magic==VDBE_MAGIC_INIT );
+  assert( op>=0 && op<0xff );
+  if( p->pParse->nOpAlloc<=i ){
+    return growOp3(p, op, p1, p2, p3);
+  }
+  p->nOp++;
+  pOp = &p->aOp[i];
+  pOp->opcode = (u8)op;
+  pOp->p5 = 0;
+  pOp->p1 = p1;
+  pOp->p2 = p2;
+  pOp->p3 = p3;
+  pOp->p4.p = 0;
+  pOp->p4type = P4_NOTUSED;
+#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
+  pOp->zComment = 0;
+#endif
+#ifdef SQLITE_DEBUG
+  if( p->db->flags & SQLITE_VdbeAddopTrace ){
+    int jj, kk;
+    Parse *pParse = p->pParse;
+    for(jj=kk=0; jj<pParse->nColCache; jj++){
+      struct yColCache *x = pParse->aColCache + jj;
+      printf(" r[%d]={%d:%d}", x->iReg, x->iTable, x->iColumn);
+      kk++;
+    }
+    if( kk ) printf("\n");
+    sqlite3VdbePrintOp(0, i, &p->aOp[i]);
+    test_addop_breakpoint();
+  }
+#endif
+#ifdef VDBE_PROFILE
+  pOp->cycles = 0;
+  pOp->cnt = 0;
+#endif
+#ifdef SQLITE_VDBE_COVERAGE
+  pOp->iSrcLine = 0;
+#endif
+  return i;
+}
+int sqlite3VdbeAddOp0(Vdbe *p, int op){
+  return sqlite3VdbeAddOp3(p, op, 0, 0, 0);
+}
+int sqlite3VdbeAddOp1(Vdbe *p, int op, int p1){
+  return sqlite3VdbeAddOp3(p, op, p1, 0, 0);
+}
+int sqlite3VdbeAddOp2(Vdbe *p, int op, int p1, int p2){
+  return sqlite3VdbeAddOp3(p, op, p1, p2, 0);
+}
+
+/* Generate code for an unconditional jump to instruction iDest
+*/
+int sqlite3VdbeGoto(Vdbe *p, int iDest){
+  return sqlite3VdbeAddOp3(p, OP_Goto, 0, iDest, 0);
+}
+
+/* Generate code to cause the string zStr to be loaded into
+** register iDest
+*/
+int sqlite3VdbeLoadString(Vdbe *p, int iDest, const char *zStr){
+  return sqlite3VdbeAddOp4(p, OP_String8, 0, iDest, 0, zStr, 0);
+}
+
+/*
+** Generate code that initializes multiple registers to string or integer
+** constants.  The registers begin with iDest and increase consecutively.
+** One register is initialized for each characgter in zTypes[].  For each
+** "s" character in zTypes[], the register is a string if the argument is
+** not NULL, or OP_Null if the value is a null pointer.  For each "i" character
+** in zTypes[], the register is initialized to an integer.
+*/
+void sqlite3VdbeMultiLoad(Vdbe *p, int iDest, const char *zTypes, ...){
+  va_list ap;
+  int i;
+  char c;
+  va_start(ap, zTypes);
+  for(i=0; (c = zTypes[i])!=0; i++){
+    if( c=='s' ){
+      const char *z = va_arg(ap, const char*);
+      sqlite3VdbeAddOp4(p, z==0 ? OP_Null : OP_String8, 0, iDest++, 0, z, 0);
+    }else{
+      assert( c=='i' );
+      sqlite3VdbeAddOp2(p, OP_Integer, va_arg(ap, int), iDest++);
+    }
+  }
+  va_end(ap);
+}
+
+/*
+** Add an opcode that includes the p4 value as a pointer.
+*/
+int sqlite3VdbeAddOp4(
+  Vdbe *p,            /* Add the opcode to this VM */
+  int op,             /* The new opcode */
+  int p1,             /* The P1 operand */
+  int p2,             /* The P2 operand */
+  int p3,             /* The P3 operand */
+  const char *zP4,    /* The P4 operand */
+  int p4type          /* P4 operand type */
+){
+  int addr = sqlite3VdbeAddOp3(p, op, p1, p2, p3);
+  sqlite3VdbeChangeP4(p, addr, zP4, p4type);
+  return addr;
+}
+
+/*
+** Add an opcode that includes the p4 value with a P4_INT64 or
+** P4_REAL type.
+*/
+int sqlite3VdbeAddOp4Dup8(
+  Vdbe *p,            /* Add the opcode to this VM */
+  int op,             /* The new opcode */
+  int p1,             /* The P1 operand */
+  int p2,             /* The P2 operand */
+  int p3,             /* The P3 operand */
+  const u8 *zP4,      /* The P4 operand */
+  int p4type          /* P4 operand type */
+){
+  char *p4copy = sqlite3DbMallocRawNN(sqlite3VdbeDb(p), 8);
+  if( p4copy ) memcpy(p4copy, zP4, 8);
+  return sqlite3VdbeAddOp4(p, op, p1, p2, p3, p4copy, p4type);
+}
+
+/*
+** Add an OP_ParseSchema opcode.  This routine is broken out from
+** sqlite3VdbeAddOp4() since it needs to also needs to mark all btrees
+** as having been used.
+**
+** The zWhere string must have been obtained from sqlite3_malloc().
+** This routine will take ownership of the allocated memory.
+*/
+void sqlite3VdbeAddParseSchemaOp(Vdbe *p, int iDb, char *zWhere){
+  int j;
+  sqlite3VdbeAddOp4(p, OP_ParseSchema, iDb, 0, 0, zWhere, P4_DYNAMIC);
+  for(j=0; j<p->db->nDb; j++) sqlite3VdbeUsesBtree(p, j);
+}
+
+/*
+** Add an opcode that includes the p4 value as an integer.
+*/
+int sqlite3VdbeAddOp4Int(
+  Vdbe *p,            /* Add the opcode to this VM */
+  int op,             /* The new opcode */
+  int p1,             /* The P1 operand */
+  int p2,             /* The P2 operand */
+  int p3,             /* The P3 operand */
+  int p4              /* The P4 operand as an integer */
+){
+  int addr = sqlite3VdbeAddOp3(p, op, p1, p2, p3);
+  if( p->db->mallocFailed==0 ){
+    VdbeOp *pOp = &p->aOp[addr];
+    pOp->p4type = P4_INT32;
+    pOp->p4.i = p4;
+  }
+  return addr;
+}
+
+/* Insert the end of a co-routine
+*/
+void sqlite3VdbeEndCoroutine(Vdbe *v, int regYield){
+  sqlite3VdbeAddOp1(v, OP_EndCoroutine, regYield);
+
+  /* Clear the temporary register cache, thereby ensuring that each
+  ** co-routine has its own independent set of registers, because co-routines
+  ** might expect their registers to be preserved across an OP_Yield, and
+  ** that could cause problems if two or more co-routines are using the same
+  ** temporary register.
+  */
+  v->pParse->nTempReg = 0;
+  v->pParse->nRangeReg = 0;
+}
+
+/*
+** Create a new symbolic label for an instruction that has yet to be
+** coded.  The symbolic label is really just a negative number.  The
+** label can be used as the P2 value of an operation.  Later, when
+** the label is resolved to a specific address, the VDBE will scan
+** through its operation list and change all values of P2 which match
+** the label into the resolved address.
+**
+** The VDBE knows that a P2 value is a label because labels are
+** always negative and P2 values are suppose to be non-negative.
+** Hence, a negative P2 value is a label that has yet to be resolved.
+**
+** Zero is returned if a malloc() fails.
+*/
+int sqlite3VdbeMakeLabel(Vdbe *v){
+  Parse *p = v->pParse;
+  int i = p->nLabel++;
+  assert( v->magic==VDBE_MAGIC_INIT );
+  if( (i & (i-1))==0 ){
+    p->aLabel = sqlite3DbReallocOrFree(p->db, p->aLabel, 
+                                       (i*2+1)*sizeof(p->aLabel[0]));
+  }
+  if( p->aLabel ){
+    p->aLabel[i] = -1;
+  }
+  return ADDR(i);
+}
+
+/*
+** Resolve label "x" to be the address of the next instruction to
+** be inserted.  The parameter "x" must have been obtained from
+** a prior call to sqlite3VdbeMakeLabel().
+*/
+void sqlite3VdbeResolveLabel(Vdbe *v, int x){
+  Parse *p = v->pParse;
+  int j = ADDR(x);
+  assert( v->magic==VDBE_MAGIC_INIT );
+  assert( j<p->nLabel );
+  assert( j>=0 );
+  if( p->aLabel ){
+    p->aLabel[j] = v->nOp;
+  }
+}
+
+/*
+** Mark the VDBE as one that can only be run one time.
+*/
+void sqlite3VdbeRunOnlyOnce(Vdbe *p){
+  p->runOnlyOnce = 1;
+}
+
+/*
+** Mark the VDBE as one that can only be run multiple times.
+*/
+void sqlite3VdbeReusable(Vdbe *p){
+  p->runOnlyOnce = 0;
+}
+
+#ifdef SQLITE_DEBUG /* sqlite3AssertMayAbort() logic */
+
+/*
+** The following type and function are used to iterate through all opcodes
+** in a Vdbe main program and each of the sub-programs (triggers) it may 
+** invoke directly or indirectly. It should be used as follows:
+**
+**   Op *pOp;
+**   VdbeOpIter sIter;
+**
+**   memset(&sIter, 0, sizeof(sIter));
+**   sIter.v = v;                            // v is of type Vdbe* 
+**   while( (pOp = opIterNext(&sIter)) ){
+**     // Do something with pOp
+**   }
+**   sqlite3DbFree(v->db, sIter.apSub);
+** 
+*/
+typedef struct VdbeOpIter VdbeOpIter;
+struct VdbeOpIter {
+  Vdbe *v;                   /* Vdbe to iterate through the opcodes of */
+  SubProgram **apSub;        /* Array of subprograms */
+  int nSub;                  /* Number of entries in apSub */
+  int iAddr;                 /* Address of next instruction to return */
+  int iSub;                  /* 0 = main program, 1 = first sub-program etc. */
+};
+static Op *opIterNext(VdbeOpIter *p){
+  Vdbe *v = p->v;
+  Op *pRet = 0;
+  Op *aOp;
+  int nOp;
+
+  if( p->iSub<=p->nSub ){
+
+    if( p->iSub==0 ){
+      aOp = v->aOp;
+      nOp = v->nOp;
+    }else{
+      aOp = p->apSub[p->iSub-1]->aOp;
+      nOp = p->apSub[p->iSub-1]->nOp;
+    }
+    assert( p->iAddr<nOp );
+
+    pRet = &aOp[p->iAddr];
+    p->iAddr++;
+    if( p->iAddr==nOp ){
+      p->iSub++;
+      p->iAddr = 0;
+    }
+  
+    if( pRet->p4type==P4_SUBPROGRAM ){
+      int nByte = (p->nSub+1)*sizeof(SubProgram*);
+      int j;
+      for(j=0; j<p->nSub; j++){
+        if( p->apSub[j]==pRet->p4.pProgram ) break;
+      }
+      if( j==p->nSub ){
+        p->apSub = sqlite3DbReallocOrFree(v->db, p->apSub, nByte);
+        if( !p->apSub ){
+          pRet = 0;
+        }else{
+          p->apSub[p->nSub++] = pRet->p4.pProgram;
+        }
+      }
+    }
+  }
+
+  return pRet;
+}
+
+/*
+** Check if the program stored in the VM associated with pParse may
+** throw an ABORT exception (causing the statement, but not entire transaction
+** to be rolled back). This condition is true if the main program or any
+** sub-programs contains any of the following:
+**
+**   *  OP_Halt with P1=SQLITE_CONSTRAINT and P2=OE_Abort.
+**   *  OP_HaltIfNull with P1=SQLITE_CONSTRAINT and P2=OE_Abort.
+**   *  OP_Destroy
+**   *  OP_VUpdate
+**   *  OP_VRename
+**   *  OP_FkCounter with P2==0 (immediate foreign key constraint)
+**   *  OP_CreateTable and OP_InitCoroutine (for CREATE TABLE AS SELECT ...)
+**
+** Then check that the value of Parse.mayAbort is true if an
+** ABORT may be thrown, or false otherwise. Return true if it does
+** match, or false otherwise. This function is intended to be used as
+** part of an assert statement in the compiler. Similar to:
+**
+**   assert( sqlite3VdbeAssertMayAbort(pParse->pVdbe, pParse->mayAbort) );
+*/
+int sqlite3VdbeAssertMayAbort(Vdbe *v, int mayAbort){
+  int hasAbort = 0;
+  int hasFkCounter = 0;
+  int hasCreateTable = 0;
+  int hasInitCoroutine = 0;
+  Op *pOp;
+  VdbeOpIter sIter;
+  memset(&sIter, 0, sizeof(sIter));
+  sIter.v = v;
+
+  while( (pOp = opIterNext(&sIter))!=0 ){
+    int opcode = pOp->opcode;
+    if( opcode==OP_Destroy || opcode==OP_VUpdate || opcode==OP_VRename 
+     || ((opcode==OP_Halt || opcode==OP_HaltIfNull) 
+      && ((pOp->p1&0xff)==SQLITE_CONSTRAINT && pOp->p2==OE_Abort))
+    ){
+      hasAbort = 1;
+      break;
+    }
+    if( opcode==OP_CreateTable ) hasCreateTable = 1;
+    if( opcode==OP_InitCoroutine ) hasInitCoroutine = 1;
+#ifndef SQLITE_OMIT_FOREIGN_KEY
+    if( opcode==OP_FkCounter && pOp->p1==0 && pOp->p2==1 ){
+      hasFkCounter = 1;
+    }
+#endif
+  }
+  sqlite3DbFree(v->db, sIter.apSub);
+
+  /* Return true if hasAbort==mayAbort. Or if a malloc failure occurred.
+  ** If malloc failed, then the while() loop above may not have iterated
+  ** through all opcodes and hasAbort may be set incorrectly. Return
+  ** true for this case to prevent the assert() in the callers frame
+  ** from failing.  */
+  return ( v->db->mallocFailed || hasAbort==mayAbort || hasFkCounter
+              || (hasCreateTable && hasInitCoroutine) );
+}
+#endif /* SQLITE_DEBUG - the sqlite3AssertMayAbort() function */
+
+/*
+** This routine is called after all opcodes have been inserted.  It loops
+** through all the opcodes and fixes up some details.
+**
+** (1) For each jump instruction with a negative P2 value (a label)
+**     resolve the P2 value to an actual address.
+**
+** (2) Compute the maximum number of arguments used by any SQL function
+**     and store that value in *pMaxFuncArgs.
+**
+** (3) Update the Vdbe.readOnly and Vdbe.bIsReader flags to accurately
+**     indicate what the prepared statement actually does.
+**
+** (4) Initialize the p4.xAdvance pointer on opcodes that use it.
+**
+** (5) Reclaim the memory allocated for storing labels.
+**
+** This routine will only function correctly if the mkopcodeh.tcl generator
+** script numbers the opcodes correctly.  Changes to this routine must be
+** coordinated with changes to mkopcodeh.tcl.
+*/
+static void resolveP2Values(Vdbe *p, int *pMaxFuncArgs){
+  int nMaxArgs = *pMaxFuncArgs;
+  Op *pOp;
+  Parse *pParse = p->pParse;
+  int *aLabel = pParse->aLabel;
+  p->readOnly = 1;
+  p->bIsReader = 0;
+  pOp = &p->aOp[p->nOp-1];
+  while(1){
+
+    /* Only JUMP opcodes and the short list of special opcodes in the switch
+    ** below need to be considered.  The mkopcodeh.tcl generator script groups
+    ** all these opcodes together near the front of the opcode list.  Skip
+    ** any opcode that does not need processing by virtual of the fact that
+    ** it is larger than SQLITE_MX_JUMP_OPCODE, as a performance optimization.
+    */
+    if( pOp->opcode<=SQLITE_MX_JUMP_OPCODE ){
+      /* NOTE: Be sure to update mkopcodeh.tcl when adding or removing
+      ** cases from this switch! */
+      switch( pOp->opcode ){
+        case OP_Transaction: {
+          if( pOp->p2!=0 ) p->readOnly = 0;
+          /* fall thru */
+        }
+        case OP_AutoCommit:
+        case OP_Savepoint: {
+          p->bIsReader = 1;
+          break;
+        }
+#ifndef SQLITE_OMIT_WAL
+        case OP_Checkpoint:
+#endif
+        case OP_Vacuum:
+        case OP_JournalMode: {
+          p->readOnly = 0;
+          p->bIsReader = 1;
+          break;
+        }
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+        case OP_VUpdate: {
+          if( pOp->p2>nMaxArgs ) nMaxArgs = pOp->p2;
+          break;
+        }
+        case OP_VFilter: {
+          int n;
+          assert( (pOp - p->aOp) >= 3 );
+          assert( pOp[-1].opcode==OP_Integer );
+          n = pOp[-1].p1;
+          if( n>nMaxArgs ) nMaxArgs = n;
+          break;
+        }
+#endif
+        case OP_Next:
+        case OP_NextIfOpen:
+        case OP_SorterNext: {
+          pOp->p4.xAdvance = sqlite3BtreeNext;
+          pOp->p4type = P4_ADVANCE;
+          break;
+        }
+        case OP_Prev:
+        case OP_PrevIfOpen: {
+          pOp->p4.xAdvance = sqlite3BtreePrevious;
+          pOp->p4type = P4_ADVANCE;
+          break;
+        }
+      }
+      if( (sqlite3OpcodeProperty[pOp->opcode] & OPFLG_JUMP)!=0 && pOp->p2<0 ){
+        assert( ADDR(pOp->p2)<pParse->nLabel );
+        pOp->p2 = aLabel[ADDR(pOp->p2)];
+      }
+    }
+    if( pOp==p->aOp ) break;
+    pOp--;
+  }
+  sqlite3DbFree(p->db, pParse->aLabel);
+  pParse->aLabel = 0;
+  pParse->nLabel = 0;
+  *pMaxFuncArgs = nMaxArgs;
+  assert( p->bIsReader!=0 || DbMaskAllZero(p->btreeMask) );
+}
+
+/*
+** Return the address of the next instruction to be inserted.
+*/
+int sqlite3VdbeCurrentAddr(Vdbe *p){
+  assert( p->magic==VDBE_MAGIC_INIT );
+  return p->nOp;
+}
+
+/*
+** Verify that at least N opcode slots are available in p without
+** having to malloc for more space (except when compiled using
+** SQLITE_TEST_REALLOC_STRESS).  This interface is used during testing
+** to verify that certain calls to sqlite3VdbeAddOpList() can never
+** fail due to a OOM fault and hence that the return value from
+** sqlite3VdbeAddOpList() will always be non-NULL.
+*/
+#if defined(SQLITE_DEBUG) && !defined(SQLITE_TEST_REALLOC_STRESS)
+void sqlite3VdbeVerifyNoMallocRequired(Vdbe *p, int N){
+  assert( p->nOp + N <= p->pParse->nOpAlloc );
+}
+#endif
+
+/*
+** Verify that the VM passed as the only argument does not contain
+** an OP_ResultRow opcode. Fail an assert() if it does. This is used
+** by code in pragma.c to ensure that the implementation of certain
+** pragmas comports with the flags specified in the mkpragmatab.tcl
+** script.
+*/
+#if defined(SQLITE_DEBUG) && !defined(SQLITE_TEST_REALLOC_STRESS)
+void sqlite3VdbeVerifyNoResultRow(Vdbe *p){
+  int i;
+  for(i=0; i<p->nOp; i++){
+    assert( p->aOp[i].opcode!=OP_ResultRow );
+  }
+}
+#endif
+
+/*
+** This function returns a pointer to the array of opcodes associated with
+** the Vdbe passed as the first argument. It is the callers responsibility
+** to arrange for the returned array to be eventually freed using the 
+** vdbeFreeOpArray() function.
+**
+** Before returning, *pnOp is set to the number of entries in the returned
+** array. Also, *pnMaxArg is set to the larger of its current value and 
+** the number of entries in the Vdbe.apArg[] array required to execute the 
+** returned program.
+*/
+VdbeOp *sqlite3VdbeTakeOpArray(Vdbe *p, int *pnOp, int *pnMaxArg){
+  VdbeOp *aOp = p->aOp;
+  assert( aOp && !p->db->mallocFailed );
+
+  /* Check that sqlite3VdbeUsesBtree() was not called on this VM */
+  assert( DbMaskAllZero(p->btreeMask) );
+
+  resolveP2Values(p, pnMaxArg);
+  *pnOp = p->nOp;
+  p->aOp = 0;
+  return aOp;
+}
+
+/*
+** Add a whole list of operations to the operation stack.  Return a
+** pointer to the first operation inserted.
+**
+** Non-zero P2 arguments to jump instructions are automatically adjusted
+** so that the jump target is relative to the first operation inserted.
+*/
+VdbeOp *sqlite3VdbeAddOpList(
+  Vdbe *p,                     /* Add opcodes to the prepared statement */
+  int nOp,                     /* Number of opcodes to add */
+  VdbeOpList const *aOp,       /* The opcodes to be added */
+  int iLineno                  /* Source-file line number of first opcode */
+){
+  int i;
+  VdbeOp *pOut, *pFirst;
+  assert( nOp>0 );
+  assert( p->magic==VDBE_MAGIC_INIT );
+  if( p->nOp + nOp > p->pParse->nOpAlloc && growOpArray(p, nOp) ){
+    return 0;
+  }
+  pFirst = pOut = &p->aOp[p->nOp];
+  for(i=0; i<nOp; i++, aOp++, pOut++){
+    pOut->opcode = aOp->opcode;
+    pOut->p1 = aOp->p1;
+    pOut->p2 = aOp->p2;
+    assert( aOp->p2>=0 );
+    if( (sqlite3OpcodeProperty[aOp->opcode] & OPFLG_JUMP)!=0 && aOp->p2>0 ){
+      pOut->p2 += p->nOp;
+    }
+    pOut->p3 = aOp->p3;
+    pOut->p4type = P4_NOTUSED;
+    pOut->p4.p = 0;
+    pOut->p5 = 0;
+#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
+    pOut->zComment = 0;
+#endif
+#ifdef SQLITE_VDBE_COVERAGE
+    pOut->iSrcLine = iLineno+i;
+#else
+    (void)iLineno;
+#endif
+#ifdef SQLITE_DEBUG
+    if( p->db->flags & SQLITE_VdbeAddopTrace ){
+      sqlite3VdbePrintOp(0, i+p->nOp, &p->aOp[i+p->nOp]);
+    }
+#endif
+  }
+  p->nOp += nOp;
+  return pFirst;
+}
+
+#if defined(SQLITE_ENABLE_STMT_SCANSTATUS)
+/*
+** Add an entry to the array of counters managed by sqlite3_stmt_scanstatus().
+*/
+void sqlite3VdbeScanStatus(
+  Vdbe *p,                        /* VM to add scanstatus() to */
+  int addrExplain,                /* Address of OP_Explain (or 0) */
+  int addrLoop,                   /* Address of loop counter */ 
+  int addrVisit,                  /* Address of rows visited counter */
+  LogEst nEst,                    /* Estimated number of output rows */
+  const char *zName               /* Name of table or index being scanned */
+){
+  int nByte = (p->nScan+1) * sizeof(ScanStatus);
+  ScanStatus *aNew;
+  aNew = (ScanStatus*)sqlite3DbRealloc(p->db, p->aScan, nByte);
+  if( aNew ){
+    ScanStatus *pNew = &aNew[p->nScan++];
+    pNew->addrExplain = addrExplain;
+    pNew->addrLoop = addrLoop;
+    pNew->addrVisit = addrVisit;
+    pNew->nEst = nEst;
+    pNew->zName = sqlite3DbStrDup(p->db, zName);
+    p->aScan = aNew;
+  }
+}
+#endif
+
+
+/*
+** Change the value of the opcode, or P1, P2, P3, or P5 operands
+** for a specific instruction.
+*/
+void sqlite3VdbeChangeOpcode(Vdbe *p, u32 addr, u8 iNewOpcode){
+  sqlite3VdbeGetOp(p,addr)->opcode = iNewOpcode;
+}
+void sqlite3VdbeChangeP1(Vdbe *p, u32 addr, int val){
+  sqlite3VdbeGetOp(p,addr)->p1 = val;
+}
+void sqlite3VdbeChangeP2(Vdbe *p, u32 addr, int val){
+  sqlite3VdbeGetOp(p,addr)->p2 = val;
+}
+void sqlite3VdbeChangeP3(Vdbe *p, u32 addr, int val){
+  sqlite3VdbeGetOp(p,addr)->p3 = val;
+}
+void sqlite3VdbeChangeP5(Vdbe *p, u16 p5){
+  assert( p->nOp>0 || p->db->mallocFailed );
+  if( p->nOp>0 ) p->aOp[p->nOp-1].p5 = p5;
+}
+
+/*
+** Change the P2 operand of instruction addr so that it points to
+** the address of the next instruction to be coded.
+*/
+void sqlite3VdbeJumpHere(Vdbe *p, int addr){
+  sqlite3VdbeChangeP2(p, addr, p->nOp);
+}
+
+
+/*
+** If the input FuncDef structure is ephemeral, then free it.  If
+** the FuncDef is not ephermal, then do nothing.
+*/
+static void freeEphemeralFunction(sqlite3 *db, FuncDef *pDef){
+  if( (pDef->funcFlags & SQLITE_FUNC_EPHEM)!=0 ){
+    sqlite3DbFree(db, pDef);
+  }
+}
+
+static void vdbeFreeOpArray(sqlite3 *, Op *, int);
+
+/*
+** Delete a P4 value if necessary.
+*/
+static SQLITE_NOINLINE void freeP4Mem(sqlite3 *db, Mem *p){
+  if( p->szMalloc ) sqlite3DbFree(db, p->zMalloc);
+  sqlite3DbFree(db, p);
+}
+static SQLITE_NOINLINE void freeP4FuncCtx(sqlite3 *db, sqlite3_context *p){
+  freeEphemeralFunction(db, p->pFunc);
+  sqlite3DbFree(db, p);
+}
+static void freeP4(sqlite3 *db, int p4type, void *p4){
+  assert( db );
+  switch( p4type ){
+    case P4_FUNCCTX: {
+      freeP4FuncCtx(db, (sqlite3_context*)p4);
+      break;
+    }
+    case P4_REAL:
+    case P4_INT64:
+    case P4_DYNAMIC:
+    case P4_INTARRAY: {
+      sqlite3DbFree(db, p4);
+      break;
+    }
+    case P4_KEYINFO: {
+      if( db->pnBytesFreed==0 ) sqlite3KeyInfoUnref((KeyInfo*)p4);
+      break;
+    }
+#ifdef SQLITE_ENABLE_CURSOR_HINTS
+    case P4_EXPR: {
+      sqlite3ExprDelete(db, (Expr*)p4);
+      break;
+    }
+#endif
+    case P4_FUNCDEF: {
+      freeEphemeralFunction(db, (FuncDef*)p4);
+      break;
+    }
+    case P4_MEM: {
+      if( db->pnBytesFreed==0 ){
+        sqlite3ValueFree((sqlite3_value*)p4);
+      }else{
+        freeP4Mem(db, (Mem*)p4);
+      }
+      break;
+    }
+    case P4_VTAB : {
+      if( db->pnBytesFreed==0 ) sqlite3VtabUnlock((VTable *)p4);
+      break;
+    }
+  }
+}
+
+/*
+** Free the space allocated for aOp and any p4 values allocated for the
+** opcodes contained within. If aOp is not NULL it is assumed to contain 
+** nOp entries. 
+*/
+static void vdbeFreeOpArray(sqlite3 *db, Op *aOp, int nOp){
+  if( aOp ){
+    Op *pOp;
+    for(pOp=aOp; pOp<&aOp[nOp]; pOp++){
+      if( pOp->p4type ) freeP4(db, pOp->p4type, pOp->p4.p);
+#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
+      sqlite3DbFree(db, pOp->zComment);
+#endif     
+    }
+  }
+  sqlite3DbFree(db, aOp);
+}
+
+/*
+** Link the SubProgram object passed as the second argument into the linked
+** list at Vdbe.pSubProgram. This list is used to delete all sub-program
+** objects when the VM is no longer required.
+*/
+void sqlite3VdbeLinkSubProgram(Vdbe *pVdbe, SubProgram *p){
+  p->pNext = pVdbe->pProgram;
+  pVdbe->pProgram = p;
+}
+
+/*
+** Change the opcode at addr into OP_Noop
+*/
+int sqlite3VdbeChangeToNoop(Vdbe *p, int addr){
+  VdbeOp *pOp;
+  if( p->db->mallocFailed ) return 0;
+  assert( addr>=0 && addr<p->nOp );
+  pOp = &p->aOp[addr];
+  freeP4(p->db, pOp->p4type, pOp->p4.p);
+  pOp->p4type = P4_NOTUSED;
+  pOp->p4.z = 0;
+  pOp->opcode = OP_Noop;
+  return 1;
+}
+
+/*
+** If the last opcode is "op" and it is not a jump destination,
+** then remove it.  Return true if and only if an opcode was removed.
+*/
+int sqlite3VdbeDeletePriorOpcode(Vdbe *p, u8 op){
+  if( p->nOp>0 && p->aOp[p->nOp-1].opcode==op ){
+    return sqlite3VdbeChangeToNoop(p, p->nOp-1);
+  }else{
+    return 0;
+  }
+}
+
+/*
+** Change the value of the P4 operand for a specific instruction.
+** This routine is useful when a large program is loaded from a
+** static array using sqlite3VdbeAddOpList but we want to make a
+** few minor changes to the program.
+**
+** If n>=0 then the P4 operand is dynamic, meaning that a copy of
+** the string is made into memory obtained from sqlite3_malloc().
+** A value of n==0 means copy bytes of zP4 up to and including the
+** first null byte.  If n>0 then copy n+1 bytes of zP4.
+** 
+** Other values of n (P4_STATIC, P4_COLLSEQ etc.) indicate that zP4 points
+** to a string or structure that is guaranteed to exist for the lifetime of
+** the Vdbe. In these cases we can just copy the pointer.
+**
+** If addr<0 then change P4 on the most recently inserted instruction.
+*/
+static void SQLITE_NOINLINE vdbeChangeP4Full(
+  Vdbe *p,
+  Op *pOp,
+  const char *zP4,
+  int n
+){
+  if( pOp->p4type ){
+    freeP4(p->db, pOp->p4type, pOp->p4.p);
+    pOp->p4type = 0;
+    pOp->p4.p = 0;
+  }
+  if( n<0 ){
+    sqlite3VdbeChangeP4(p, (int)(pOp - p->aOp), zP4, n);
+  }else{
+    if( n==0 ) n = sqlite3Strlen30(zP4);
+    pOp->p4.z = sqlite3DbStrNDup(p->db, zP4, n);
+    pOp->p4type = P4_DYNAMIC;
+  }
+}
+void sqlite3VdbeChangeP4(Vdbe *p, int addr, const char *zP4, int n){
+  Op *pOp;
+  sqlite3 *db;
+  assert( p!=0 );
+  db = p->db;
+  assert( p->magic==VDBE_MAGIC_INIT );
+  assert( p->aOp!=0 || db->mallocFailed );
+  if( db->mallocFailed ){
+    if( n!=P4_VTAB ) freeP4(db, n, (void*)*(char**)&zP4);
+    return;
+  }
+  assert( p->nOp>0 );
+  assert( addr<p->nOp );
+  if( addr<0 ){
+    addr = p->nOp - 1;
+  }
+  pOp = &p->aOp[addr];
+  if( n>=0 || pOp->p4type ){
+    vdbeChangeP4Full(p, pOp, zP4, n);
+    return;
+  }
+  if( n==P4_INT32 ){
+    /* Note: this cast is safe, because the origin data point was an int
+    ** that was cast to a (const char *). */
+    pOp->p4.i = SQLITE_PTR_TO_INT(zP4);
+    pOp->p4type = P4_INT32;
+  }else if( zP4!=0 ){
+    assert( n<0 );
+    pOp->p4.p = (void*)zP4;
+    pOp->p4type = (signed char)n;
+    if( n==P4_VTAB ) sqlite3VtabLock((VTable*)zP4);
+  }
+}
+
+/*
+** Change the P4 operand of the most recently coded instruction 
+** to the value defined by the arguments.  This is a high-speed
+** version of sqlite3VdbeChangeP4().
+**
+** The P4 operand must not have been previously defined.  And the new
+** P4 must not be P4_INT32.  Use sqlite3VdbeChangeP4() in either of
+** those cases.
+*/
+void sqlite3VdbeAppendP4(Vdbe *p, void *pP4, int n){
+  VdbeOp *pOp;
+  assert( n!=P4_INT32 && n!=P4_VTAB );
+  assert( n<=0 );
+  if( p->db->mallocFailed ){
+    freeP4(p->db, n, pP4);
+  }else{
+    assert( pP4!=0 );
+    assert( p->nOp>0 );
+    pOp = &p->aOp[p->nOp-1];
+    assert( pOp->p4type==P4_NOTUSED );
+    pOp->p4type = n;
+    pOp->p4.p = pP4;
+  }
+}
+
+/*
+** Set the P4 on the most recently added opcode to the KeyInfo for the
+** index given.
+*/
+void sqlite3VdbeSetP4KeyInfo(Parse *pParse, Index *pIdx){
+  Vdbe *v = pParse->pVdbe;
+  KeyInfo *pKeyInfo;
+  assert( v!=0 );
+  assert( pIdx!=0 );
+  pKeyInfo = sqlite3KeyInfoOfIndex(pParse, pIdx);
+  if( pKeyInfo ) sqlite3VdbeAppendP4(v, pKeyInfo, P4_KEYINFO);
+}
+
+#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
+/*
+** Change the comment on the most recently coded instruction.  Or
+** insert a No-op and add the comment to that new instruction.  This
+** makes the code easier to read during debugging.  None of this happens
+** in a production build.
+*/
+static void vdbeVComment(Vdbe *p, const char *zFormat, va_list ap){
+  assert( p->nOp>0 || p->aOp==0 );
+  assert( p->aOp==0 || p->aOp[p->nOp-1].zComment==0 || p->db->mallocFailed );
+  if( p->nOp ){
+    assert( p->aOp );
+    sqlite3DbFree(p->db, p->aOp[p->nOp-1].zComment);
+    p->aOp[p->nOp-1].zComment = sqlite3VMPrintf(p->db, zFormat, ap);
+  }
+}
+void sqlite3VdbeComment(Vdbe *p, const char *zFormat, ...){
+  va_list ap;
+  if( p ){
+    va_start(ap, zFormat);
+    vdbeVComment(p, zFormat, ap);
+    va_end(ap);
+  }
+}
+void sqlite3VdbeNoopComment(Vdbe *p, const char *zFormat, ...){
+  va_list ap;
+  if( p ){
+    sqlite3VdbeAddOp0(p, OP_Noop);
+    va_start(ap, zFormat);
+    vdbeVComment(p, zFormat, ap);
+    va_end(ap);
+  }
+}
+#endif  /* NDEBUG */
+
+#ifdef SQLITE_VDBE_COVERAGE
+/*
+** Set the value if the iSrcLine field for the previously coded instruction.
+*/
+void sqlite3VdbeSetLineNumber(Vdbe *v, int iLine){
+  sqlite3VdbeGetOp(v,-1)->iSrcLine = iLine;
+}
+#endif /* SQLITE_VDBE_COVERAGE */
+
+/*
+** Return the opcode for a given address.  If the address is -1, then
+** return the most recently inserted opcode.
+**
+** If a memory allocation error has occurred prior to the calling of this
+** routine, then a pointer to a dummy VdbeOp will be returned.  That opcode
+** is readable but not writable, though it is cast to a writable value.
+** The return of a dummy opcode allows the call to continue functioning
+** after an OOM fault without having to check to see if the return from 
+** this routine is a valid pointer.  But because the dummy.opcode is 0,
+** dummy will never be written to.  This is verified by code inspection and
+** by running with Valgrind.
+*/
+VdbeOp *sqlite3VdbeGetOp(Vdbe *p, int addr){
+  /* C89 specifies that the constant "dummy" will be initialized to all
+  ** zeros, which is correct.  MSVC generates a warning, nevertheless. */
+  static VdbeOp dummy;  /* Ignore the MSVC warning about no initializer */
+  assert( p->magic==VDBE_MAGIC_INIT );
+  if( addr<0 ){
+    addr = p->nOp - 1;
+  }
+  assert( (addr>=0 && addr<p->nOp) || p->db->mallocFailed );
+  if( p->db->mallocFailed ){
+    return (VdbeOp*)&dummy;
+  }else{
+    return &p->aOp[addr];
+  }
+}
+
+#if defined(SQLITE_ENABLE_EXPLAIN_COMMENTS)
+/*
+** Return an integer value for one of the parameters to the opcode pOp
+** determined by character c.
+*/
+static int translateP(char c, const Op *pOp){
+  if( c=='1' ) return pOp->p1;
+  if( c=='2' ) return pOp->p2;
+  if( c=='3' ) return pOp->p3;
+  if( c=='4' ) return pOp->p4.i;
+  return pOp->p5;
+}
+
+/*
+** Compute a string for the "comment" field of a VDBE opcode listing.
+**
+** The Synopsis: field in comments in the vdbe.c source file gets converted
+** to an extra string that is appended to the sqlite3OpcodeName().  In the
+** absence of other comments, this synopsis becomes the comment on the opcode.
+** Some translation occurs:
+**
+**       "PX"      ->  "r[X]"
+**       "PX@PY"   ->  "r[X..X+Y-1]"  or "r[x]" if y is 0 or 1
+**       "PX@PY+1" ->  "r[X..X+Y]"    or "r[x]" if y is 0
+**       "PY..PY"  ->  "r[X..Y]"      or "r[x]" if y<=x
+*/
+static int displayComment(
+  const Op *pOp,     /* The opcode to be commented */
+  const char *zP4,   /* Previously obtained value for P4 */
+  char *zTemp,       /* Write result here */
+  int nTemp          /* Space available in zTemp[] */
+){
+  const char *zOpName;
+  const char *zSynopsis;
+  int nOpName;
+  int ii, jj;
+  char zAlt[50];
+  zOpName = sqlite3OpcodeName(pOp->opcode);
+  nOpName = sqlite3Strlen30(zOpName);
+  if( zOpName[nOpName+1] ){
+    int seenCom = 0;
+    char c;
+    zSynopsis = zOpName += nOpName + 1;
+    if( strncmp(zSynopsis,"IF ",3)==0 ){
+      if( pOp->p5 & SQLITE_STOREP2 ){
+        sqlite3_snprintf(sizeof(zAlt), zAlt, "r[P2] = (%s)", zSynopsis+3);
+      }else{
+        sqlite3_snprintf(sizeof(zAlt), zAlt, "if %s goto P2", zSynopsis+3);
+      }
+      zSynopsis = zAlt;
+    }
+    for(ii=jj=0; jj<nTemp-1 && (c = zSynopsis[ii])!=0; ii++){
+      if( c=='P' ){
+        c = zSynopsis[++ii];
+        if( c=='4' ){
+          sqlite3_snprintf(nTemp-jj, zTemp+jj, "%s", zP4);
+        }else if( c=='X' ){
+          sqlite3_snprintf(nTemp-jj, zTemp+jj, "%s", pOp->zComment);
+          seenCom = 1;
+        }else{
+          int v1 = translateP(c, pOp);
+          int v2;
+          sqlite3_snprintf(nTemp-jj, zTemp+jj, "%d", v1);
+          if( strncmp(zSynopsis+ii+1, "@P", 2)==0 ){
+            ii += 3;
+            jj += sqlite3Strlen30(zTemp+jj);
+            v2 = translateP(zSynopsis[ii], pOp);
+            if( strncmp(zSynopsis+ii+1,"+1",2)==0 ){
+              ii += 2;
+              v2++;
+            }
+            if( v2>1 ){
+              sqlite3_snprintf(nTemp-jj, zTemp+jj, "..%d", v1+v2-1);
+            }
+          }else if( strncmp(zSynopsis+ii+1, "..P3", 4)==0 && pOp->p3==0 ){
+            ii += 4;
+          }
+        }
+        jj += sqlite3Strlen30(zTemp+jj);
+      }else{
+        zTemp[jj++] = c;
+      }
+    }
+    if( !seenCom && jj<nTemp-5 && pOp->zComment ){
+      sqlite3_snprintf(nTemp-jj, zTemp+jj, "; %s", pOp->zComment);
+      jj += sqlite3Strlen30(zTemp+jj);
+    }
+    if( jj<nTemp ) zTemp[jj] = 0;
+  }else if( pOp->zComment ){
+    sqlite3_snprintf(nTemp, zTemp, "%s", pOp->zComment);
+    jj = sqlite3Strlen30(zTemp);
+  }else{
+    zTemp[0] = 0;
+    jj = 0;
+  }
+  return jj;
+}
+#endif /* SQLITE_DEBUG */
+
+#if VDBE_DISPLAY_P4 && defined(SQLITE_ENABLE_CURSOR_HINTS)
+/*
+** Translate the P4.pExpr value for an OP_CursorHint opcode into text
+** that can be displayed in the P4 column of EXPLAIN output.
+*/
+static void displayP4Expr(StrAccum *p, Expr *pExpr){
+  const char *zOp = 0;
+  switch( pExpr->op ){
+    case TK_STRING:
+      sqlite3XPrintf(p, "%Q", pExpr->u.zToken);
+      break;
+    case TK_INTEGER:
+      sqlite3XPrintf(p, "%d", pExpr->u.iValue);
+      break;
+    case TK_NULL:
+      sqlite3XPrintf(p, "NULL");
+      break;
+    case TK_REGISTER: {
+      sqlite3XPrintf(p, "r[%d]", pExpr->iTable);
+      break;
+    }
+    case TK_COLUMN: {
+      if( pExpr->iColumn<0 ){
+        sqlite3XPrintf(p, "rowid");
+      }else{
+        sqlite3XPrintf(p, "c%d", (int)pExpr->iColumn);
+      }
+      break;
+    }
+    case TK_LT:      zOp = "LT";      break;
+    case TK_LE:      zOp = "LE";      break;
+    case TK_GT:      zOp = "GT";      break;
+    case TK_GE:      zOp = "GE";      break;
+    case TK_NE:      zOp = "NE";      break;
+    case TK_EQ:      zOp = "EQ";      break;
+    case TK_IS:      zOp = "IS";      break;
+    case TK_ISNOT:   zOp = "ISNOT";   break;
+    case TK_AND:     zOp = "AND";     break;
+    case TK_OR:      zOp = "OR";      break;
+    case TK_PLUS:    zOp = "ADD";     break;
+    case TK_STAR:    zOp = "MUL";     break;
+    case TK_MINUS:   zOp = "SUB";     break;
+    case TK_REM:     zOp = "REM";     break;
+    case TK_BITAND:  zOp = "BITAND";  break;
+    case TK_BITOR:   zOp = "BITOR";   break;
+    case TK_SLASH:   zOp = "DIV";     break;
+    case TK_LSHIFT:  zOp = "LSHIFT";  break;
+    case TK_RSHIFT:  zOp = "RSHIFT";  break;
+    case TK_CONCAT:  zOp = "CONCAT";  break;
+    case TK_UMINUS:  zOp = "MINUS";   break;
+    case TK_UPLUS:   zOp = "PLUS";    break;
+    case TK_BITNOT:  zOp = "BITNOT";  break;
+    case TK_NOT:     zOp = "NOT";     break;
+    case TK_ISNULL:  zOp = "ISNULL";  break;
+    case TK_NOTNULL: zOp = "NOTNULL"; break;
+
+    default:
+      sqlite3XPrintf(p, "%s", "expr");
+      break;
+  }
+
+  if( zOp ){
+    sqlite3XPrintf(p, "%s(", zOp);
+    displayP4Expr(p, pExpr->pLeft);
+    if( pExpr->pRight ){
+      sqlite3StrAccumAppend(p, ",", 1);
+      displayP4Expr(p, pExpr->pRight);
+    }
+    sqlite3StrAccumAppend(p, ")", 1);
+  }
+}
+#endif /* VDBE_DISPLAY_P4 && defined(SQLITE_ENABLE_CURSOR_HINTS) */
+
+
+#if VDBE_DISPLAY_P4
+/*
+** Compute a string that describes the P4 parameter for an opcode.
+** Use zTemp for any required temporary buffer space.
+*/
+static char *displayP4(Op *pOp, char *zTemp, int nTemp){
+  char *zP4 = zTemp;
+  StrAccum x;
+  assert( nTemp>=20 );
+  sqlite3StrAccumInit(&x, 0, zTemp, nTemp, 0);
+  switch( pOp->p4type ){
+    case P4_KEYINFO: {
+      int j;
+      KeyInfo *pKeyInfo = pOp->p4.pKeyInfo;
+      assert( pKeyInfo->aSortOrder!=0 );
+      sqlite3XPrintf(&x, "k(%d", pKeyInfo->nField);
+      for(j=0; j<pKeyInfo->nField; j++){
+        CollSeq *pColl = pKeyInfo->aColl[j];
+        const char *zColl = pColl ? pColl->zName : "";
+        if( strcmp(zColl, "BINARY")==0 ) zColl = "B";
+        sqlite3XPrintf(&x, ",%s%s", pKeyInfo->aSortOrder[j] ? "-" : "", zColl);
+      }
+      sqlite3StrAccumAppend(&x, ")", 1);
+      break;
+    }
+#ifdef SQLITE_ENABLE_CURSOR_HINTS
+    case P4_EXPR: {
+      displayP4Expr(&x, pOp->p4.pExpr);
+      break;
+    }
+#endif
+    case P4_COLLSEQ: {
+      CollSeq *pColl = pOp->p4.pColl;
+      sqlite3XPrintf(&x, "(%.20s)", pColl->zName);
+      break;
+    }
+    case P4_FUNCDEF: {
+      FuncDef *pDef = pOp->p4.pFunc;
+      sqlite3XPrintf(&x, "%s(%d)", pDef->zName, pDef->nArg);
+      break;
+    }
+#if defined(SQLITE_DEBUG) || defined(VDBE_PROFILE)
+    case P4_FUNCCTX: {
+      FuncDef *pDef = pOp->p4.pCtx->pFunc;
+      sqlite3XPrintf(&x, "%s(%d)", pDef->zName, pDef->nArg);
+      break;
+    }
+#endif
+    case P4_INT64: {
+      sqlite3XPrintf(&x, "%lld", *pOp->p4.pI64);
+      break;
+    }
+    case P4_INT32: {
+      sqlite3XPrintf(&x, "%d", pOp->p4.i);
+      break;
+    }
+    case P4_REAL: {
+      sqlite3XPrintf(&x, "%.16g", *pOp->p4.pReal);
+      break;
+    }
+    case P4_MEM: {
+      Mem *pMem = pOp->p4.pMem;
+      if( pMem->flags & MEM_Str ){
+        zP4 = pMem->z;
+      }else if( pMem->flags & MEM_Int ){
+        sqlite3XPrintf(&x, "%lld", pMem->u.i);
+      }else if( pMem->flags & MEM_Real ){
+        sqlite3XPrintf(&x, "%.16g", pMem->u.r);
+      }else if( pMem->flags & MEM_Null ){
+        zP4 = "NULL";
+      }else{
+        assert( pMem->flags & MEM_Blob );
+        zP4 = "(blob)";
+      }
+      break;
+    }
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+    case P4_VTAB: {
+      sqlite3_vtab *pVtab = pOp->p4.pVtab->pVtab;
+      sqlite3XPrintf(&x, "vtab:%p", pVtab);
+      break;
+    }
+#endif
+    case P4_INTARRAY: {
+      int i;
+      int *ai = pOp->p4.ai;
+      int n = ai[0];   /* The first element of an INTARRAY is always the
+                       ** count of the number of elements to follow */
+      for(i=1; i<n; i++){
+        sqlite3XPrintf(&x, ",%d", ai[i]);
+      }
+      zTemp[0] = '[';
+      sqlite3StrAccumAppend(&x, "]", 1);
+      break;
+    }
+    case P4_SUBPROGRAM: {
+      sqlite3XPrintf(&x, "program");
+      break;
+    }
+    case P4_ADVANCE: {
+      zTemp[0] = 0;
+      break;
+    }
+    case P4_TABLE: {
+      sqlite3XPrintf(&x, "%s", pOp->p4.pTab->zName);
+      break;
+    }
+    default: {
+      zP4 = pOp->p4.z;
+      if( zP4==0 ){
+        zP4 = zTemp;
+        zTemp[0] = 0;
+      }
+    }
+  }
+  sqlite3StrAccumFinish(&x);
+  assert( zP4!=0 );
+  return zP4;
+}
+#endif /* VDBE_DISPLAY_P4 */
+
+/*
+** Declare to the Vdbe that the BTree object at db->aDb[i] is used.
+**
+** The prepared statements need to know in advance the complete set of
+** attached databases that will be use.  A mask of these databases
+** is maintained in p->btreeMask.  The p->lockMask value is the subset of
+** p->btreeMask of databases that will require a lock.
+*/
+void sqlite3VdbeUsesBtree(Vdbe *p, int i){
+  assert( i>=0 && i<p->db->nDb && i<(int)sizeof(yDbMask)*8 );
+  assert( i<(int)sizeof(p->btreeMask)*8 );
+  DbMaskSet(p->btreeMask, i);
+  if( i!=1 && sqlite3BtreeSharable(p->db->aDb[i].pBt) ){
+    DbMaskSet(p->lockMask, i);
+  }
+}
+
+#if !defined(SQLITE_OMIT_SHARED_CACHE)
+/*
+** If SQLite is compiled to support shared-cache mode and to be threadsafe,
+** this routine obtains the mutex associated with each BtShared structure
+** that may be accessed by the VM passed as an argument. In doing so it also
+** sets the BtShared.db member of each of the BtShared structures, ensuring
+** that the correct busy-handler callback is invoked if required.
+**
+** If SQLite is not threadsafe but does support shared-cache mode, then
+** sqlite3BtreeEnter() is invoked to set the BtShared.db variables
+** of all of BtShared structures accessible via the database handle 
+** associated with the VM.
+**
+** If SQLite is not threadsafe and does not support shared-cache mode, this
+** function is a no-op.
+**
+** The p->btreeMask field is a bitmask of all btrees that the prepared 
+** statement p will ever use.  Let N be the number of bits in p->btreeMask
+** corresponding to btrees that use shared cache.  Then the runtime of
+** this routine is N*N.  But as N is rarely more than 1, this should not
+** be a problem.
+*/
+void sqlite3VdbeEnter(Vdbe *p){
+  int i;
+  sqlite3 *db;
+  Db *aDb;
+  int nDb;
+  if( DbMaskAllZero(p->lockMask) ) return;  /* The common case */
+  db = p->db;
+  aDb = db->aDb;
+  nDb = db->nDb;
+  for(i=0; i<nDb; i++){
+    if( i!=1 && DbMaskTest(p->lockMask,i) && ALWAYS(aDb[i].pBt!=0) ){
+      sqlite3BtreeEnter(aDb[i].pBt);
+    }
+  }
+}
+#endif
+
+#if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE>0
+/*
+** Unlock all of the btrees previously locked by a call to sqlite3VdbeEnter().
+*/
+static SQLITE_NOINLINE void vdbeLeave(Vdbe *p){
+  int i;
+  sqlite3 *db;
+  Db *aDb;
+  int nDb;
+  db = p->db;
+  aDb = db->aDb;
+  nDb = db->nDb;
+  for(i=0; i<nDb; i++){
+    if( i!=1 && DbMaskTest(p->lockMask,i) && ALWAYS(aDb[i].pBt!=0) ){
+      sqlite3BtreeLeave(aDb[i].pBt);
+    }
+  }
+}
+void sqlite3VdbeLeave(Vdbe *p){
+  if( DbMaskAllZero(p->lockMask) ) return;  /* The common case */
+  vdbeLeave(p);
+}
+#endif
+
+#if defined(VDBE_PROFILE) || defined(SQLITE_DEBUG)
+/*
+** Print a single opcode.  This routine is used for debugging only.
+*/
+void sqlite3VdbePrintOp(FILE *pOut, int pc, Op *pOp){
+  char *zP4;
+  char zPtr[50];
+  char zCom[100];
+  static const char *zFormat1 = "%4d %-13s %4d %4d %4d %-13s %.2X %s\n";
+  if( pOut==0 ) pOut = stdout;
+  zP4 = displayP4(pOp, zPtr, sizeof(zPtr));
+#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
+  displayComment(pOp, zP4, zCom, sizeof(zCom));
+#else
+  zCom[0] = 0;
+#endif
+  /* NB:  The sqlite3OpcodeName() function is implemented by code created
+  ** by the mkopcodeh.awk and mkopcodec.awk scripts which extract the
+  ** information from the vdbe.c source text */
+  fprintf(pOut, zFormat1, pc, 
+      sqlite3OpcodeName(pOp->opcode), pOp->p1, pOp->p2, pOp->p3, zP4, pOp->p5,
+      zCom
+  );
+  fflush(pOut);
+}
+#endif
+
+/*
+** Initialize an array of N Mem element.
+*/
+static void initMemArray(Mem *p, int N, sqlite3 *db, u16 flags){
+  while( (N--)>0 ){
+    p->db = db;
+    p->flags = flags;
+    p->szMalloc = 0;
+#ifdef SQLITE_DEBUG
+    p->pScopyFrom = 0;
+#endif
+    p++;
+  }
+}
+
+/*
+** Release an array of N Mem elements
+*/
+static void releaseMemArray(Mem *p, int N){
+  if( p && N ){
+    Mem *pEnd = &p[N];
+    sqlite3 *db = p->db;
+    if( db->pnBytesFreed ){
+      do{
+        if( p->szMalloc ) sqlite3DbFree(db, p->zMalloc);
+      }while( (++p)<pEnd );
+      return;
+    }
+    do{
+      assert( (&p[1])==pEnd || p[0].db==p[1].db );
+      assert( sqlite3VdbeCheckMemInvariants(p) );
+
+      /* This block is really an inlined version of sqlite3VdbeMemRelease()
+      ** that takes advantage of the fact that the memory cell value is 
+      ** being set to NULL after releasing any dynamic resources.
+      **
+      ** The justification for duplicating code is that according to 
+      ** callgrind, this causes a certain test case to hit the CPU 4.7 
+      ** percent less (x86 linux, gcc version 4.1.2, -O6) than if 
+      ** sqlite3MemRelease() were called from here. With -O2, this jumps
+      ** to 6.6 percent. The test case is inserting 1000 rows into a table 
+      ** with no indexes using a single prepared INSERT statement, bind() 
+      ** and reset(). Inserts are grouped into a transaction.
+      */
+      testcase( p->flags & MEM_Agg );
+      testcase( p->flags & MEM_Dyn );
+      testcase( p->flags & MEM_Frame );
+      testcase( p->flags & MEM_RowSet );
+      if( p->flags&(MEM_Agg|MEM_Dyn|MEM_Frame|MEM_RowSet) ){
+        sqlite3VdbeMemRelease(p);
+      }else if( p->szMalloc ){
+        sqlite3DbFree(db, p->zMalloc);
+        p->szMalloc = 0;
+      }
+
+      p->flags = MEM_Undefined;
+    }while( (++p)<pEnd );
+  }
+}
+
+/*
+** Delete a VdbeFrame object and its contents. VdbeFrame objects are
+** allocated by the OP_Program opcode in sqlite3VdbeExec().
+*/
+void sqlite3VdbeFrameDelete(VdbeFrame *p){
+  int i;
+  Mem *aMem = VdbeFrameMem(p);
+  VdbeCursor **apCsr = (VdbeCursor **)&aMem[p->nChildMem];
+  for(i=0; i<p->nChildCsr; i++){
+    sqlite3VdbeFreeCursor(p->v, apCsr[i]);
+  }
+  releaseMemArray(aMem, p->nChildMem);
+  sqlite3VdbeDeleteAuxData(p->v->db, &p->pAuxData, -1, 0);
+  sqlite3DbFree(p->v->db, p);
+}
+
+#ifndef SQLITE_OMIT_EXPLAIN
+/*
+** Give a listing of the program in the virtual machine.
+**
+** The interface is the same as sqlite3VdbeExec().  But instead of
+** running the code, it invokes the callback once for each instruction.
+** This feature is used to implement "EXPLAIN".
+**
+** When p->explain==1, each instruction is listed.  When
+** p->explain==2, only OP_Explain instructions are listed and these
+** are shown in a different format.  p->explain==2 is used to implement
+** EXPLAIN QUERY PLAN.
+**
+** When p->explain==1, first the main program is listed, then each of
+** the trigger subprograms are listed one by one.
+*/
+int sqlite3VdbeList(
+  Vdbe *p                   /* The VDBE */
+){
+  int nRow;                            /* Stop when row count reaches this */
+  int nSub = 0;                        /* Number of sub-vdbes seen so far */
+  SubProgram **apSub = 0;              /* Array of sub-vdbes */
+  Mem *pSub = 0;                       /* Memory cell hold array of subprogs */
+  sqlite3 *db = p->db;                 /* The database connection */
+  int i;                               /* Loop counter */
+  int rc = SQLITE_OK;                  /* Return code */
+  Mem *pMem = &p->aMem[1];             /* First Mem of result set */
+
+  assert( p->explain );
+  assert( p->magic==VDBE_MAGIC_RUN );
+  assert( p->rc==SQLITE_OK || p->rc==SQLITE_BUSY || p->rc==SQLITE_NOMEM );
+
+  /* Even though this opcode does not use dynamic strings for
+  ** the result, result columns may become dynamic if the user calls
+  ** sqlite3_column_text16(), causing a translation to UTF-16 encoding.
+  */
+  releaseMemArray(pMem, 8);
+  p->pResultSet = 0;
+
+  if( p->rc==SQLITE_NOMEM_BKPT ){
+    /* This happens if a malloc() inside a call to sqlite3_column_text() or
+    ** sqlite3_column_text16() failed.  */
+    sqlite3OomFault(db);
+    return SQLITE_ERROR;
+  }
+
+  /* When the number of output rows reaches nRow, that means the
+  ** listing has finished and sqlite3_step() should return SQLITE_DONE.
+  ** nRow is the sum of the number of rows in the main program, plus
+  ** the sum of the number of rows in all trigger subprograms encountered
+  ** so far.  The nRow value will increase as new trigger subprograms are
+  ** encountered, but p->pc will eventually catch up to nRow.
+  */
+  nRow = p->nOp;
+  if( p->explain==1 ){
+    /* The first 8 memory cells are used for the result set.  So we will
+    ** commandeer the 9th cell to use as storage for an array of pointers
+    ** to trigger subprograms.  The VDBE is guaranteed to have at least 9
+    ** cells.  */
+    assert( p->nMem>9 );
+    pSub = &p->aMem[9];
+    if( pSub->flags&MEM_Blob ){
+      /* On the first call to sqlite3_step(), pSub will hold a NULL.  It is
+      ** initialized to a BLOB by the P4_SUBPROGRAM processing logic below */
+      nSub = pSub->n/sizeof(Vdbe*);
+      apSub = (SubProgram **)pSub->z;
+    }
+    for(i=0; i<nSub; i++){
+      nRow += apSub[i]->nOp;
+    }
+  }
+
+  do{
+    i = p->pc++;
+  }while( i<nRow && p->explain==2 && p->aOp[i].opcode!=OP_Explain );
+  if( i>=nRow ){
+    p->rc = SQLITE_OK;
+    rc = SQLITE_DONE;
+  }else if( db->u1.isInterrupted ){
+    p->rc = SQLITE_INTERRUPT;
+    rc = SQLITE_ERROR;
+    sqlite3VdbeError(p, sqlite3ErrStr(p->rc));
+  }else{
+    char *zP4;
+    Op *pOp;
+    if( i<p->nOp ){
+      /* The output line number is small enough that we are still in the
+      ** main program. */
+      pOp = &p->aOp[i];
+    }else{
+      /* We are currently listing subprograms.  Figure out which one and
+      ** pick up the appropriate opcode. */
+      int j;
+      i -= p->nOp;
+      for(j=0; i>=apSub[j]->nOp; j++){
+        i -= apSub[j]->nOp;
+      }
+      pOp = &apSub[j]->aOp[i];
+    }
+    if( p->explain==1 ){
+      pMem->flags = MEM_Int;
+      pMem->u.i = i;                                /* Program counter */
+      pMem++;
+  
+      pMem->flags = MEM_Static|MEM_Str|MEM_Term;
+      pMem->z = (char*)sqlite3OpcodeName(pOp->opcode); /* Opcode */
+      assert( pMem->z!=0 );
+      pMem->n = sqlite3Strlen30(pMem->z);
+      pMem->enc = SQLITE_UTF8;
+      pMem++;
+
+      /* When an OP_Program opcode is encounter (the only opcode that has
+      ** a P4_SUBPROGRAM argument), expand the size of the array of subprograms
+      ** kept in p->aMem[9].z to hold the new program - assuming this subprogram
+      ** has not already been seen.
+      */
+      if( pOp->p4type==P4_SUBPROGRAM ){
+        int nByte = (nSub+1)*sizeof(SubProgram*);
+        int j;
+        for(j=0; j<nSub; j++){
+          if( apSub[j]==pOp->p4.pProgram ) break;
+        }
+        if( j==nSub && SQLITE_OK==sqlite3VdbeMemGrow(pSub, nByte, nSub!=0) ){
+          apSub = (SubProgram **)pSub->z;
+          apSub[nSub++] = pOp->p4.pProgram;
+          pSub->flags |= MEM_Blob;
+          pSub->n = nSub*sizeof(SubProgram*);
+        }
+      }
+    }
+
+    pMem->flags = MEM_Int;
+    pMem->u.i = pOp->p1;                          /* P1 */
+    pMem++;
+
+    pMem->flags = MEM_Int;
+    pMem->u.i = pOp->p2;                          /* P2 */
+    pMem++;
+
+    pMem->flags = MEM_Int;
+    pMem->u.i = pOp->p3;                          /* P3 */
+    pMem++;
+
+    if( sqlite3VdbeMemClearAndResize(pMem, 100) ){ /* P4 */
+      assert( p->db->mallocFailed );
+      return SQLITE_ERROR;
+    }
+    pMem->flags = MEM_Str|MEM_Term;
+    zP4 = displayP4(pOp, pMem->z, pMem->szMalloc);
+    if( zP4!=pMem->z ){
+      pMem->n = 0;
+      sqlite3VdbeMemSetStr(pMem, zP4, -1, SQLITE_UTF8, 0);
+    }else{
+      assert( pMem->z!=0 );
+      pMem->n = sqlite3Strlen30(pMem->z);
+      pMem->enc = SQLITE_UTF8;
+    }
+    pMem++;
+
+    if( p->explain==1 ){
+      if( sqlite3VdbeMemClearAndResize(pMem, 4) ){
+        assert( p->db->mallocFailed );
+        return SQLITE_ERROR;
+      }
+      pMem->flags = MEM_Str|MEM_Term;
+      pMem->n = 2;
+      sqlite3_snprintf(3, pMem->z, "%.2x", pOp->p5);   /* P5 */
+      pMem->enc = SQLITE_UTF8;
+      pMem++;
+  
+#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
+      if( sqlite3VdbeMemClearAndResize(pMem, 500) ){
+        assert( p->db->mallocFailed );
+        return SQLITE_ERROR;
+      }
+      pMem->flags = MEM_Str|MEM_Term;
+      pMem->n = displayComment(pOp, zP4, pMem->z, 500);
+      pMem->enc = SQLITE_UTF8;
+#else
+      pMem->flags = MEM_Null;                       /* Comment */
+#endif
+    }
+
+    p->nResColumn = 8 - 4*(p->explain-1);
+    p->pResultSet = &p->aMem[1];
+    p->rc = SQLITE_OK;
+    rc = SQLITE_ROW;
+  }
+  return rc;
+}
+#endif /* SQLITE_OMIT_EXPLAIN */
+
+#ifdef SQLITE_DEBUG
+/*
+** Print the SQL that was used to generate a VDBE program.
+*/
+void sqlite3VdbePrintSql(Vdbe *p){
+  const char *z = 0;
+  if( p->zSql ){
+    z = p->zSql;
+  }else if( p->nOp>=1 ){
+    const VdbeOp *pOp = &p->aOp[0];
+    if( pOp->opcode==OP_Init && pOp->p4.z!=0 ){
+      z = pOp->p4.z;
+      while( sqlite3Isspace(*z) ) z++;
+    }
+  }
+  if( z ) printf("SQL: [%s]\n", z);
+}
+#endif
+
+#if !defined(SQLITE_OMIT_TRACE) && defined(SQLITE_ENABLE_IOTRACE)
+/*
+** Print an IOTRACE message showing SQL content.
+*/
+void sqlite3VdbeIOTraceSql(Vdbe *p){
+  int nOp = p->nOp;
+  VdbeOp *pOp;
+  if( sqlite3IoTrace==0 ) return;
+  if( nOp<1 ) return;
+  pOp = &p->aOp[0];
+  if( pOp->opcode==OP_Init && pOp->p4.z!=0 ){
+    int i, j;
+    char z[1000];
+    sqlite3_snprintf(sizeof(z), z, "%s", pOp->p4.z);
+    for(i=0; sqlite3Isspace(z[i]); i++){}
+    for(j=0; z[i]; i++){
+      if( sqlite3Isspace(z[i]) ){
+        if( z[i-1]!=' ' ){
+          z[j++] = ' ';
+        }
+      }else{
+        z[j++] = z[i];
+      }
+    }
+    z[j] = 0;
+    sqlite3IoTrace("SQL %s\n", z);
+  }
+}
+#endif /* !SQLITE_OMIT_TRACE && SQLITE_ENABLE_IOTRACE */
+
+/* An instance of this object describes bulk memory available for use
+** by subcomponents of a prepared statement.  Space is allocated out
+** of a ReusableSpace object by the allocSpace() routine below.
+*/
+struct ReusableSpace {
+  u8 *pSpace;          /* Available memory */
+  int nFree;           /* Bytes of available memory */
+  int nNeeded;         /* Total bytes that could not be allocated */
+};
+
+/* Try to allocate nByte bytes of 8-byte aligned bulk memory for pBuf
+** from the ReusableSpace object.  Return a pointer to the allocated
+** memory on success.  If insufficient memory is available in the
+** ReusableSpace object, increase the ReusableSpace.nNeeded
+** value by the amount needed and return NULL.
+**
+** If pBuf is not initially NULL, that means that the memory has already
+** been allocated by a prior call to this routine, so just return a copy
+** of pBuf and leave ReusableSpace unchanged.
+**
+** This allocator is employed to repurpose unused slots at the end of the
+** opcode array of prepared state for other memory needs of the prepared
+** statement.
+*/
+static void *allocSpace(
+  struct ReusableSpace *p,  /* Bulk memory available for allocation */
+  void *pBuf,               /* Pointer to a prior allocation */
+  int nByte                 /* Bytes of memory needed */
+){
+  assert( EIGHT_BYTE_ALIGNMENT(p->pSpace) );
+  if( pBuf==0 ){
+    nByte = ROUND8(nByte);
+    if( nByte <= p->nFree ){
+      p->nFree -= nByte;
+      pBuf = &p->pSpace[p->nFree];
+    }else{
+      p->nNeeded += nByte;
+    }
+  }
+  assert( EIGHT_BYTE_ALIGNMENT(pBuf) );
+  return pBuf;
+}
+
+/*
+** Rewind the VDBE back to the beginning in preparation for
+** running it.
+*/
+void sqlite3VdbeRewind(Vdbe *p){
+#if defined(SQLITE_DEBUG) || defined(VDBE_PROFILE)
+  int i;
+#endif
+  assert( p!=0 );
+  assert( p->magic==VDBE_MAGIC_INIT || p->magic==VDBE_MAGIC_RESET );
+
+  /* There should be at least one opcode.
+  */
+  assert( p->nOp>0 );
+
+  /* Set the magic to VDBE_MAGIC_RUN sooner rather than later. */
+  p->magic = VDBE_MAGIC_RUN;
+
+#ifdef SQLITE_DEBUG
+  for(i=0; i<p->nMem; i++){
+    assert( p->aMem[i].db==p->db );
+  }
+#endif
+  p->pc = -1;
+  p->rc = SQLITE_OK;
+  p->errorAction = OE_Abort;
+  p->nChange = 0;
+  p->cacheCtr = 1;
+  p->minWriteFileFormat = 255;
+  p->iStatement = 0;
+  p->nFkConstraint = 0;
+#ifdef VDBE_PROFILE
+  for(i=0; i<p->nOp; i++){
+    p->aOp[i].cnt = 0;
+    p->aOp[i].cycles = 0;
+  }
+#endif
+}
+
+/*
+** Prepare a virtual machine for execution for the first time after
+** creating the virtual machine.  This involves things such
+** as allocating registers and initializing the program counter.
+** After the VDBE has be prepped, it can be executed by one or more
+** calls to sqlite3VdbeExec().  
+**
+** This function may be called exactly once on each virtual machine.
+** After this routine is called the VM has been "packaged" and is ready
+** to run.  After this routine is called, further calls to 
+** sqlite3VdbeAddOp() functions are prohibited.  This routine disconnects
+** the Vdbe from the Parse object that helped generate it so that the
+** the Vdbe becomes an independent entity and the Parse object can be
+** destroyed.
+**
+** Use the sqlite3VdbeRewind() procedure to restore a virtual machine back
+** to its initial state after it has been run.
+*/
+void sqlite3VdbeMakeReady(
+  Vdbe *p,                       /* The VDBE */
+  Parse *pParse                  /* Parsing context */
+){
+  sqlite3 *db;                   /* The database connection */
+  int nVar;                      /* Number of parameters */
+  int nMem;                      /* Number of VM memory registers */
+  int nCursor;                   /* Number of cursors required */
+  int nArg;                      /* Number of arguments in subprograms */
+  int n;                         /* Loop counter */
+  struct ReusableSpace x;        /* Reusable bulk memory */
+
+  assert( p!=0 );
+  assert( p->nOp>0 );
+  assert( pParse!=0 );
+  assert( p->magic==VDBE_MAGIC_INIT );
+  assert( pParse==p->pParse );
+  db = p->db;
+  assert( db->mallocFailed==0 );
+  nVar = pParse->nVar;
+  nMem = pParse->nMem;
+  nCursor = pParse->nTab;
+  nArg = pParse->nMaxArg;
+  
+  /* Each cursor uses a memory cell.  The first cursor (cursor 0) can
+  ** use aMem[0] which is not otherwise used by the VDBE program.  Allocate
+  ** space at the end of aMem[] for cursors 1 and greater.
+  ** See also: allocateCursor().
+  */
+  nMem += nCursor;
+  if( nCursor==0 && nMem>0 ) nMem++;  /* Space for aMem[0] even if not used */
+
+  /* Figure out how much reusable memory is available at the end of the
+  ** opcode array.  This extra memory will be reallocated for other elements
+  ** of the prepared statement.
+  */
+  n = ROUND8(sizeof(Op)*p->nOp);              /* Bytes of opcode memory used */
+  x.pSpace = &((u8*)p->aOp)[n];               /* Unused opcode memory */
+  assert( EIGHT_BYTE_ALIGNMENT(x.pSpace) );
+  x.nFree = ROUNDDOWN8(pParse->szOpAlloc - n);  /* Bytes of unused memory */
+  assert( x.nFree>=0 );
+  assert( EIGHT_BYTE_ALIGNMENT(&x.pSpace[x.nFree]) );
+
+  resolveP2Values(p, &nArg);
+  p->usesStmtJournal = (u8)(pParse->isMultiWrite && pParse->mayAbort);
+  if( pParse->explain && nMem<10 ){
+    nMem = 10;
+  }
+  p->expired = 0;
+
+  /* Memory for registers, parameters, cursor, etc, is allocated in one or two
+  ** passes.  On the first pass, we try to reuse unused memory at the 
+  ** end of the opcode array.  If we are unable to satisfy all memory
+  ** requirements by reusing the opcode array tail, then the second
+  ** pass will fill in the remainder using a fresh memory allocation.  
+  **
+  ** This two-pass approach that reuses as much memory as possible from
+  ** the leftover memory at the end of the opcode array.  This can significantly
+  ** reduce the amount of memory held by a prepared statement.
+  */
+  do {
+    x.nNeeded = 0;
+    p->aMem = allocSpace(&x, p->aMem, nMem*sizeof(Mem));
+    p->aVar = allocSpace(&x, p->aVar, nVar*sizeof(Mem));
+    p->apArg = allocSpace(&x, p->apArg, nArg*sizeof(Mem*));
+    p->apCsr = allocSpace(&x, p->apCsr, nCursor*sizeof(VdbeCursor*));
+#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
+    p->anExec = allocSpace(&x, p->anExec, p->nOp*sizeof(i64));
+#endif
+    if( x.nNeeded==0 ) break;
+    x.pSpace = p->pFree = sqlite3DbMallocRawNN(db, x.nNeeded);
+    x.nFree = x.nNeeded;
+  }while( !db->mallocFailed );
+
+  p->pVList = pParse->pVList;
+  pParse->pVList =  0;
+  p->explain = pParse->explain;
+  if( db->mallocFailed ){
+    p->nVar = 0;
+    p->nCursor = 0;
+    p->nMem = 0;
+  }else{
+    p->nCursor = nCursor;
+    p->nVar = (ynVar)nVar;
+    initMemArray(p->aVar, nVar, db, MEM_Null);
+    p->nMem = nMem;
+    initMemArray(p->aMem, nMem, db, MEM_Undefined);
+    memset(p->apCsr, 0, nCursor*sizeof(VdbeCursor*));
+#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
+    memset(p->anExec, 0, p->nOp*sizeof(i64));
+#endif
+  }
+  sqlite3VdbeRewind(p);
+}
+
+/*
+** Close a VDBE cursor and release all the resources that cursor 
+** happens to hold.
+*/
+void sqlite3VdbeFreeCursor(Vdbe *p, VdbeCursor *pCx){
+  if( pCx==0 ){
+    return;
+  }
+  assert( pCx->pBtx==0 || pCx->eCurType==CURTYPE_BTREE );
+  switch( pCx->eCurType ){
+    case CURTYPE_SORTER: {
+      sqlite3VdbeSorterClose(p->db, pCx);
+      break;
+    }
+    case CURTYPE_BTREE: {
+      if( pCx->pBtx ){
+        sqlite3BtreeClose(pCx->pBtx);
+        /* The pCx->pCursor will be close automatically, if it exists, by
+        ** the call above. */
+      }else{
+        assert( pCx->uc.pCursor!=0 );
+        sqlite3BtreeCloseCursor(pCx->uc.pCursor);
+      }
+      break;
+    }
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+    case CURTYPE_VTAB: {
+      sqlite3_vtab_cursor *pVCur = pCx->uc.pVCur;
+      const sqlite3_module *pModule = pVCur->pVtab->pModule;
+      assert( pVCur->pVtab->nRef>0 );
+      pVCur->pVtab->nRef--;
+      pModule->xClose(pVCur);
+      break;
+    }
+#endif
+  }
+}
+
+/*
+** Close all cursors in the current frame.
+*/
+static void closeCursorsInFrame(Vdbe *p){
+  if( p->apCsr ){
+    int i;
+    for(i=0; i<p->nCursor; i++){
+      VdbeCursor *pC = p->apCsr[i];
+      if( pC ){
+        sqlite3VdbeFreeCursor(p, pC);
+        p->apCsr[i] = 0;
+      }
+    }
+  }
+}
+
+/*
+** Copy the values stored in the VdbeFrame structure to its Vdbe. This
+** is used, for example, when a trigger sub-program is halted to restore
+** control to the main program.
+*/
+int sqlite3VdbeFrameRestore(VdbeFrame *pFrame){
+  Vdbe *v = pFrame->v;
+  closeCursorsInFrame(v);
+#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
+  v->anExec = pFrame->anExec;
+#endif
+  v->aOp = pFrame->aOp;
+  v->nOp = pFrame->nOp;
+  v->aMem = pFrame->aMem;
+  v->nMem = pFrame->nMem;
+  v->apCsr = pFrame->apCsr;
+  v->nCursor = pFrame->nCursor;
+  v->db->lastRowid = pFrame->lastRowid;
+  v->nChange = pFrame->nChange;
+  v->db->nChange = pFrame->nDbChange;
+  sqlite3VdbeDeleteAuxData(v->db, &v->pAuxData, -1, 0);
+  v->pAuxData = pFrame->pAuxData;
+  pFrame->pAuxData = 0;
+  return pFrame->pc;
+}
+
+/*
+** Close all cursors.
+**
+** Also release any dynamic memory held by the VM in the Vdbe.aMem memory 
+** cell array. This is necessary as the memory cell array may contain
+** pointers to VdbeFrame objects, which may in turn contain pointers to
+** open cursors.
+*/
+static void closeAllCursors(Vdbe *p){
+  if( p->pFrame ){
+    VdbeFrame *pFrame;
+    for(pFrame=p->pFrame; pFrame->pParent; pFrame=pFrame->pParent);
+    sqlite3VdbeFrameRestore(pFrame);
+    p->pFrame = 0;
+    p->nFrame = 0;
+  }
+  assert( p->nFrame==0 );
+  closeCursorsInFrame(p);
+  if( p->aMem ){
+    releaseMemArray(p->aMem, p->nMem);
+  }
+  while( p->pDelFrame ){
+    VdbeFrame *pDel = p->pDelFrame;
+    p->pDelFrame = pDel->pParent;
+    sqlite3VdbeFrameDelete(pDel);
+  }
+
+  /* Delete any auxdata allocations made by the VM */
+  if( p->pAuxData ) sqlite3VdbeDeleteAuxData(p->db, &p->pAuxData, -1, 0);
+  assert( p->pAuxData==0 );
+}
+
+/*
+** Clean up the VM after a single run.
+*/
+static void Cleanup(Vdbe *p){
+  sqlite3 *db = p->db;
+
+#ifdef SQLITE_DEBUG
+  /* Execute assert() statements to ensure that the Vdbe.apCsr[] and 
+  ** Vdbe.aMem[] arrays have already been cleaned up.  */
+  int i;
+  if( p->apCsr ) for(i=0; i<p->nCursor; i++) assert( p->apCsr[i]==0 );
+  if( p->aMem ){
+    for(i=0; i<p->nMem; i++) assert( p->aMem[i].flags==MEM_Undefined );
+  }
+#endif
+
+  sqlite3DbFree(db, p->zErrMsg);
+  p->zErrMsg = 0;
+  p->pResultSet = 0;
+}
+
+/*
+** Set the number of result columns that will be returned by this SQL
+** statement. This is now set at compile time, rather than during
+** execution of the vdbe program so that sqlite3_column_count() can
+** be called on an SQL statement before sqlite3_step().
+*/
+void sqlite3VdbeSetNumCols(Vdbe *p, int nResColumn){
+  Mem *pColName;
+  int n;
+  sqlite3 *db = p->db;
+
+  releaseMemArray(p->aColName, p->nResColumn*COLNAME_N);
+  sqlite3DbFree(db, p->aColName);
+  n = nResColumn*COLNAME_N;
+  p->nResColumn = (u16)nResColumn;
+  p->aColName = pColName = (Mem*)sqlite3DbMallocRawNN(db, sizeof(Mem)*n );
+  if( p->aColName==0 ) return;
+  initMemArray(p->aColName, n, p->db, MEM_Null);
+}
+
+/*
+** Set the name of the idx'th column to be returned by the SQL statement.
+** zName must be a pointer to a nul terminated string.
+**
+** This call must be made after a call to sqlite3VdbeSetNumCols().
+**
+** The final parameter, xDel, must be one of SQLITE_DYNAMIC, SQLITE_STATIC
+** or SQLITE_TRANSIENT. If it is SQLITE_DYNAMIC, then the buffer pointed
+** to by zName will be freed by sqlite3DbFree() when the vdbe is destroyed.
+*/
+int sqlite3VdbeSetColName(
+  Vdbe *p,                         /* Vdbe being configured */
+  int idx,                         /* Index of column zName applies to */
+  int var,                         /* One of the COLNAME_* constants */
+  const char *zName,               /* Pointer to buffer containing name */
+  void (*xDel)(void*)              /* Memory management strategy for zName */
+){
+  int rc;
+  Mem *pColName;
+  assert( idx<p->nResColumn );
+  assert( var<COLNAME_N );
+  if( p->db->mallocFailed ){
+    assert( !zName || xDel!=SQLITE_DYNAMIC );
+    return SQLITE_NOMEM_BKPT;
+  }
+  assert( p->aColName!=0 );
+  pColName = &(p->aColName[idx+var*p->nResColumn]);
+  rc = sqlite3VdbeMemSetStr(pColName, zName, -1, SQLITE_UTF8, xDel);
+  assert( rc!=0 || !zName || (pColName->flags&MEM_Term)!=0 );
+  return rc;
+}
+
+/*
+** A read or write transaction may or may not be active on database handle
+** db. If a transaction is active, commit it. If there is a
+** write-transaction spanning more than one database file, this routine
+** takes care of the master journal trickery.
+*/
+static int vdbeCommit(sqlite3 *db, Vdbe *p){
+  int i;
+  int nTrans = 0;  /* Number of databases with an active write-transaction
+                   ** that are candidates for a two-phase commit using a
+                   ** master-journal */
+  int rc = SQLITE_OK;
+  int needXcommit = 0;
+
+#ifdef SQLITE_OMIT_VIRTUALTABLE
+  /* With this option, sqlite3VtabSync() is defined to be simply 
+  ** SQLITE_OK so p is not used. 
+  */
+  UNUSED_PARAMETER(p);
+#endif
+
+  /* Before doing anything else, call the xSync() callback for any
+  ** virtual module tables written in this transaction. This has to
+  ** be done before determining whether a master journal file is 
+  ** required, as an xSync() callback may add an attached database
+  ** to the transaction.
+  */
+  rc = sqlite3VtabSync(db, p);
+
+  /* This loop determines (a) if the commit hook should be invoked and
+  ** (b) how many database files have open write transactions, not 
+  ** including the temp database. (b) is important because if more than 
+  ** one database file has an open write transaction, a master journal
+  ** file is required for an atomic commit.
+  */ 
+  for(i=0; rc==SQLITE_OK && i<db->nDb; i++){ 
+    Btree *pBt = db->aDb[i].pBt;
+    if( sqlite3BtreeIsInTrans(pBt) ){
+      /* Whether or not a database might need a master journal depends upon
+      ** its journal mode (among other things).  This matrix determines which
+      ** journal modes use a master journal and which do not */
+      static const u8 aMJNeeded[] = {
+        /* DELETE   */  1,
+        /* PERSIST   */ 1,
+        /* OFF       */ 0,
+        /* TRUNCATE  */ 1,
+        /* MEMORY    */ 0,
+        /* WAL       */ 0
+      };
+      Pager *pPager;   /* Pager associated with pBt */
+      needXcommit = 1;
+      sqlite3BtreeEnter(pBt);
+      pPager = sqlite3BtreePager(pBt);
+      if( db->aDb[i].safety_level!=PAGER_SYNCHRONOUS_OFF
+       && aMJNeeded[sqlite3PagerGetJournalMode(pPager)]
+      ){ 
+        assert( i!=1 );
+        nTrans++;
+      }
+      rc = sqlite3PagerExclusiveLock(pPager);
+      sqlite3BtreeLeave(pBt);
+    }
+  }
+  if( rc!=SQLITE_OK ){
+    return rc;
+  }
+
+  /* If there are any write-transactions at all, invoke the commit hook */
+  if( needXcommit && db->xCommitCallback ){
+    rc = db->xCommitCallback(db->pCommitArg);
+    if( rc ){
+      return SQLITE_CONSTRAINT_COMMITHOOK;
+    }
+  }
+
+  /* The simple case - no more than one database file (not counting the
+  ** TEMP database) has a transaction active.   There is no need for the
+  ** master-journal.
+  **
+  ** If the return value of sqlite3BtreeGetFilename() is a zero length
+  ** string, it means the main database is :memory: or a temp file.  In 
+  ** that case we do not support atomic multi-file commits, so use the 
+  ** simple case then too.
+  */
+  if( 0==sqlite3Strlen30(sqlite3BtreeGetFilename(db->aDb[0].pBt))
+   || nTrans<=1
+  ){
+    for(i=0; rc==SQLITE_OK && i<db->nDb; i++){
+      Btree *pBt = db->aDb[i].pBt;
+      if( pBt ){
+        rc = sqlite3BtreeCommitPhaseOne(pBt, 0);
+      }
+    }
+
+    /* Do the commit only if all databases successfully complete phase 1. 
+    ** If one of the BtreeCommitPhaseOne() calls fails, this indicates an
+    ** IO error while deleting or truncating a journal file. It is unlikely,
+    ** but could happen. In this case abandon processing and return the error.
+    */
+    for(i=0; rc==SQLITE_OK && i<db->nDb; i++){
+      Btree *pBt = db->aDb[i].pBt;
+      if( pBt ){
+        rc = sqlite3BtreeCommitPhaseTwo(pBt, 0);
+      }
+    }
+    if( rc==SQLITE_OK ){
+      sqlite3VtabCommit(db);
+    }
+  }
+
+  /* The complex case - There is a multi-file write-transaction active.
+  ** This requires a master journal file to ensure the transaction is
+  ** committed atomically.
+  */
+#ifndef SQLITE_OMIT_DISKIO
+  else{
+    sqlite3_vfs *pVfs = db->pVfs;
+    char *zMaster = 0;   /* File-name for the master journal */
+    char const *zMainFile = sqlite3BtreeGetFilename(db->aDb[0].pBt);
+    sqlite3_file *pMaster = 0;
+    i64 offset = 0;
+    int res;
+    int retryCount = 0;
+    int nMainFile;
+
+    /* Select a master journal file name */
+    nMainFile = sqlite3Strlen30(zMainFile);
+    zMaster = sqlite3MPrintf(db, "%s-mjXXXXXX9XXz", zMainFile);
+    if( zMaster==0 ) return SQLITE_NOMEM_BKPT;
+    do {
+      u32 iRandom;
+      if( retryCount ){
+        if( retryCount>100 ){
+          sqlite3_log(SQLITE_FULL, "MJ delete: %s", zMaster);
+          sqlite3OsDelete(pVfs, zMaster, 0);
+          break;
+        }else if( retryCount==1 ){
+          sqlite3_log(SQLITE_FULL, "MJ collide: %s", zMaster);
+        }
+      }
+      retryCount++;
+      sqlite3_randomness(sizeof(iRandom), &iRandom);
+      sqlite3_snprintf(13, &zMaster[nMainFile], "-mj%06X9%02X",
+                               (iRandom>>8)&0xffffff, iRandom&0xff);
+      /* The antipenultimate character of the master journal name must
+      ** be "9" to avoid name collisions when using 8+3 filenames. */
+      assert( zMaster[sqlite3Strlen30(zMaster)-3]=='9' );
+      sqlite3FileSuffix3(zMainFile, zMaster);
+      rc = sqlite3OsAccess(pVfs, zMaster, SQLITE_ACCESS_EXISTS, &res);
+    }while( rc==SQLITE_OK && res );
+    if( rc==SQLITE_OK ){
+      /* Open the master journal. */
+      rc = sqlite3OsOpenMalloc(pVfs, zMaster, &pMaster, 
+          SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE|
+          SQLITE_OPEN_EXCLUSIVE|SQLITE_OPEN_MASTER_JOURNAL, 0
+      );
+    }
+    if( rc!=SQLITE_OK ){
+      sqlite3DbFree(db, zMaster);
+      return rc;
+    }
+ 
+    /* Write the name of each database file in the transaction into the new
+    ** master journal file. If an error occurs at this point close
+    ** and delete the master journal file. All the individual journal files
+    ** still have 'null' as the master journal pointer, so they will roll
+    ** back independently if a failure occurs.
+    */
+    for(i=0; i<db->nDb; i++){
+      Btree *pBt = db->aDb[i].pBt;
+      if( sqlite3BtreeIsInTrans(pBt) ){
+        char const *zFile = sqlite3BtreeGetJournalname(pBt);
+        if( zFile==0 ){
+          continue;  /* Ignore TEMP and :memory: databases */
+        }
+        assert( zFile[0]!=0 );
+        rc = sqlite3OsWrite(pMaster, zFile, sqlite3Strlen30(zFile)+1, offset);
+        offset += sqlite3Strlen30(zFile)+1;
+        if( rc!=SQLITE_OK ){
+          sqlite3OsCloseFree(pMaster);
+          sqlite3OsDelete(pVfs, zMaster, 0);
+          sqlite3DbFree(db, zMaster);
+          return rc;
+        }
+      }
+    }
+
+    /* Sync the master journal file. If the IOCAP_SEQUENTIAL device
+    ** flag is set this is not required.
+    */
+    if( 0==(sqlite3OsDeviceCharacteristics(pMaster)&SQLITE_IOCAP_SEQUENTIAL)
+     && SQLITE_OK!=(rc = sqlite3OsSync(pMaster, SQLITE_SYNC_NORMAL))
+    ){
+      sqlite3OsCloseFree(pMaster);
+      sqlite3OsDelete(pVfs, zMaster, 0);
+      sqlite3DbFree(db, zMaster);
+      return rc;
+    }
+
+    /* Sync all the db files involved in the transaction. The same call
+    ** sets the master journal pointer in each individual journal. If
+    ** an error occurs here, do not delete the master journal file.
+    **
+    ** If the error occurs during the first call to
+    ** sqlite3BtreeCommitPhaseOne(), then there is a chance that the
+    ** master journal file will be orphaned. But we cannot delete it,
+    ** in case the master journal file name was written into the journal
+    ** file before the failure occurred.
+    */
+    for(i=0; rc==SQLITE_OK && i<db->nDb; i++){ 
+      Btree *pBt = db->aDb[i].pBt;
+      if( pBt ){
+        rc = sqlite3BtreeCommitPhaseOne(pBt, zMaster);
+      }
+    }
+    sqlite3OsCloseFree(pMaster);
+    assert( rc!=SQLITE_BUSY );
+    if( rc!=SQLITE_OK ){
+      sqlite3DbFree(db, zMaster);
+      return rc;
+    }
+
+    /* Delete the master journal file. This commits the transaction. After
+    ** doing this the directory is synced again before any individual
+    ** transaction files are deleted.
+    */
+    rc = sqlite3OsDelete(pVfs, zMaster, 1);
+    sqlite3DbFree(db, zMaster);
+    zMaster = 0;
+    if( rc ){
+      return rc;
+    }
+
+    /* All files and directories have already been synced, so the following
+    ** calls to sqlite3BtreeCommitPhaseTwo() are only closing files and
+    ** deleting or truncating journals. If something goes wrong while
+    ** this is happening we don't really care. The integrity of the
+    ** transaction is already guaranteed, but some stray 'cold' journals
+    ** may be lying around. Returning an error code won't help matters.
+    */
+    disable_simulated_io_errors();
+    sqlite3BeginBenignMalloc();
+    for(i=0; i<db->nDb; i++){ 
+      Btree *pBt = db->aDb[i].pBt;
+      if( pBt ){
+        sqlite3BtreeCommitPhaseTwo(pBt, 1);
+      }
+    }
+    sqlite3EndBenignMalloc();
+    enable_simulated_io_errors();
+
+    sqlite3VtabCommit(db);
+  }
+#endif
+
+  return rc;
+}
+
+/* 
+** This routine checks that the sqlite3.nVdbeActive count variable
+** matches the number of vdbe's in the list sqlite3.pVdbe that are
+** currently active. An assertion fails if the two counts do not match.
+** This is an internal self-check only - it is not an essential processing
+** step.
+**
+** This is a no-op if NDEBUG is defined.
+*/
+#ifndef NDEBUG
+static void checkActiveVdbeCnt(sqlite3 *db){
+  Vdbe *p;
+  int cnt = 0;
+  int nWrite = 0;
+  int nRead = 0;
+  p = db->pVdbe;
+  while( p ){
+    if( sqlite3_stmt_busy((sqlite3_stmt*)p) ){
+      cnt++;
+      if( p->readOnly==0 ) nWrite++;
+      if( p->bIsReader ) nRead++;
+    }
+    p = p->pNext;
+  }
+  assert( cnt==db->nVdbeActive );
+  assert( nWrite==db->nVdbeWrite );
+  assert( nRead==db->nVdbeRead );
+}
+#else
+#define checkActiveVdbeCnt(x)
+#endif
+
+/*
+** If the Vdbe passed as the first argument opened a statement-transaction,
+** close it now. Argument eOp must be either SAVEPOINT_ROLLBACK or
+** SAVEPOINT_RELEASE. If it is SAVEPOINT_ROLLBACK, then the statement
+** transaction is rolled back. If eOp is SAVEPOINT_RELEASE, then the 
+** statement transaction is committed.
+**
+** If an IO error occurs, an SQLITE_IOERR_XXX error code is returned. 
+** Otherwise SQLITE_OK.
+*/
+static SQLITE_NOINLINE int vdbeCloseStatement(Vdbe *p, int eOp){
+  sqlite3 *const db = p->db;
+  int rc = SQLITE_OK;
+  int i;
+  const int iSavepoint = p->iStatement-1;
+
+  assert( eOp==SAVEPOINT_ROLLBACK || eOp==SAVEPOINT_RELEASE);
+  assert( db->nStatement>0 );
+  assert( p->iStatement==(db->nStatement+db->nSavepoint) );
+
+  for(i=0; i<db->nDb; i++){ 
+    int rc2 = SQLITE_OK;
+    Btree *pBt = db->aDb[i].pBt;
+    if( pBt ){
+      if( eOp==SAVEPOINT_ROLLBACK ){
+        rc2 = sqlite3BtreeSavepoint(pBt, SAVEPOINT_ROLLBACK, iSavepoint);
+      }
+      if( rc2==SQLITE_OK ){
+        rc2 = sqlite3BtreeSavepoint(pBt, SAVEPOINT_RELEASE, iSavepoint);
+      }
+      if( rc==SQLITE_OK ){
+        rc = rc2;
+      }
+    }
+  }
+  db->nStatement--;
+  p->iStatement = 0;
+
+  if( rc==SQLITE_OK ){
+    if( eOp==SAVEPOINT_ROLLBACK ){
+      rc = sqlite3VtabSavepoint(db, SAVEPOINT_ROLLBACK, iSavepoint);
+    }
+    if( rc==SQLITE_OK ){
+      rc = sqlite3VtabSavepoint(db, SAVEPOINT_RELEASE, iSavepoint);
+    }
+  }
+
+  /* If the statement transaction is being rolled back, also restore the 
+  ** database handles deferred constraint counter to the value it had when 
+  ** the statement transaction was opened.  */
+  if( eOp==SAVEPOINT_ROLLBACK ){
+    db->nDeferredCons = p->nStmtDefCons;
+    db->nDeferredImmCons = p->nStmtDefImmCons;
+  }
+  return rc;
+}
+int sqlite3VdbeCloseStatement(Vdbe *p, int eOp){
+  if( p->db->nStatement && p->iStatement ){
+    return vdbeCloseStatement(p, eOp);
+  }
+  return SQLITE_OK;
+}
+
+
+/*
+** This function is called when a transaction opened by the database 
+** handle associated with the VM passed as an argument is about to be 
+** committed. If there are outstanding deferred foreign key constraint
+** violations, return SQLITE_ERROR. Otherwise, SQLITE_OK.
+**
+** If there are outstanding FK violations and this function returns 
+** SQLITE_ERROR, set the result of the VM to SQLITE_CONSTRAINT_FOREIGNKEY
+** and write an error message to it. Then return SQLITE_ERROR.
+*/
+#ifndef SQLITE_OMIT_FOREIGN_KEY
+int sqlite3VdbeCheckFk(Vdbe *p, int deferred){
+  sqlite3 *db = p->db;
+  if( (deferred && (db->nDeferredCons+db->nDeferredImmCons)>0) 
+   || (!deferred && p->nFkConstraint>0) 
+  ){
+    p->rc = SQLITE_CONSTRAINT_FOREIGNKEY;
+    p->errorAction = OE_Abort;
+    sqlite3VdbeError(p, "FOREIGN KEY constraint failed");
+    return SQLITE_ERROR;
+  }
+  return SQLITE_OK;
+}
+#endif
+
+/*
+** This routine is called the when a VDBE tries to halt.  If the VDBE
+** has made changes and is in autocommit mode, then commit those
+** changes.  If a rollback is needed, then do the rollback.
+**
+** This routine is the only way to move the state of a VM from
+** SQLITE_MAGIC_RUN to SQLITE_MAGIC_HALT.  It is harmless to
+** call this on a VM that is in the SQLITE_MAGIC_HALT state.
+**
+** Return an error code.  If the commit could not complete because of
+** lock contention, return SQLITE_BUSY.  If SQLITE_BUSY is returned, it
+** means the close did not happen and needs to be repeated.
+*/
+int sqlite3VdbeHalt(Vdbe *p){
+  int rc;                         /* Used to store transient return codes */
+  sqlite3 *db = p->db;
+
+  /* This function contains the logic that determines if a statement or
+  ** transaction will be committed or rolled back as a result of the
+  ** execution of this virtual machine. 
+  **
+  ** If any of the following errors occur:
+  **
+  **     SQLITE_NOMEM
+  **     SQLITE_IOERR
+  **     SQLITE_FULL
+  **     SQLITE_INTERRUPT
+  **
+  ** Then the internal cache might have been left in an inconsistent
+  ** state.  We need to rollback the statement transaction, if there is
+  ** one, or the complete transaction if there is no statement transaction.
+  */
+
+  if( db->mallocFailed ){
+    p->rc = SQLITE_NOMEM_BKPT;
+  }
+  closeAllCursors(p);
+  if( p->magic!=VDBE_MAGIC_RUN ){
+    return SQLITE_OK;
+  }
+  checkActiveVdbeCnt(db);
+
+  /* No commit or rollback needed if the program never started or if the
+  ** SQL statement does not read or write a database file.  */
+  if( p->pc>=0 && p->bIsReader ){
+    int mrc;   /* Primary error code from p->rc */
+    int eStatementOp = 0;
+    int isSpecialError;            /* Set to true if a 'special' error */
+
+    /* Lock all btrees used by the statement */
+    sqlite3VdbeEnter(p);
+
+    /* Check for one of the special errors */
+    mrc = p->rc & 0xff;
+    isSpecialError = mrc==SQLITE_NOMEM || mrc==SQLITE_IOERR
+                     || mrc==SQLITE_INTERRUPT || mrc==SQLITE_FULL;
+    if( isSpecialError ){
+      /* If the query was read-only and the error code is SQLITE_INTERRUPT, 
+      ** no rollback is necessary. Otherwise, at least a savepoint 
+      ** transaction must be rolled back to restore the database to a 
+      ** consistent state.
+      **
+      ** Even if the statement is read-only, it is important to perform
+      ** a statement or transaction rollback operation. If the error 
+      ** occurred while writing to the journal, sub-journal or database
+      ** file as part of an effort to free up cache space (see function
+      ** pagerStress() in pager.c), the rollback is required to restore 
+      ** the pager to a consistent state.
+      */
+      if( !p->readOnly || mrc!=SQLITE_INTERRUPT ){
+        if( (mrc==SQLITE_NOMEM || mrc==SQLITE_FULL) && p->usesStmtJournal ){
+          eStatementOp = SAVEPOINT_ROLLBACK;
+        }else{
+          /* We are forced to roll back the active transaction. Before doing
+          ** so, abort any other statements this handle currently has active.
+          */
+          sqlite3RollbackAll(db, SQLITE_ABORT_ROLLBACK);
+          sqlite3CloseSavepoints(db);
+          db->autoCommit = 1;
+          p->nChange = 0;
+        }
+      }
+    }
+
+    /* Check for immediate foreign key violations. */
+    if( p->rc==SQLITE_OK ){
+      sqlite3VdbeCheckFk(p, 0);
+    }
+  
+    /* If the auto-commit flag is set and this is the only active writer 
+    ** VM, then we do either a commit or rollback of the current transaction. 
+    **
+    ** Note: This block also runs if one of the special errors handled 
+    ** above has occurred. 
+    */
+    if( !sqlite3VtabInSync(db) 
+     && db->autoCommit 
+     && db->nVdbeWrite==(p->readOnly==0) 
+    ){
+      if( p->rc==SQLITE_OK || (p->errorAction==OE_Fail && !isSpecialError) ){
+        rc = sqlite3VdbeCheckFk(p, 1);
+        if( rc!=SQLITE_OK ){
+          if( NEVER(p->readOnly) ){
+            sqlite3VdbeLeave(p);
+            return SQLITE_ERROR;
+          }
+          rc = SQLITE_CONSTRAINT_FOREIGNKEY;
+        }else{ 
+          /* The auto-commit flag is true, the vdbe program was successful 
+          ** or hit an 'OR FAIL' constraint and there are no deferred foreign
+          ** key constraints to hold up the transaction. This means a commit 
+          ** is required. */
+          rc = vdbeCommit(db, p);
+        }
+        if( rc==SQLITE_BUSY && p->readOnly ){
+          sqlite3VdbeLeave(p);
+          return SQLITE_BUSY;
+        }else if( rc!=SQLITE_OK ){
+          p->rc = rc;
+          sqlite3RollbackAll(db, SQLITE_OK);
+          p->nChange = 0;
+        }else{
+          db->nDeferredCons = 0;
+          db->nDeferredImmCons = 0;
+          db->flags &= ~SQLITE_DeferFKs;
+          sqlite3CommitInternalChanges(db);
+        }
+      }else{
+        sqlite3RollbackAll(db, SQLITE_OK);
+        p->nChange = 0;
+      }
+      db->nStatement = 0;
+    }else if( eStatementOp==0 ){
+      if( p->rc==SQLITE_OK || p->errorAction==OE_Fail ){
+        eStatementOp = SAVEPOINT_RELEASE;
+      }else if( p->errorAction==OE_Abort ){
+        eStatementOp = SAVEPOINT_ROLLBACK;
+      }else{
+        sqlite3RollbackAll(db, SQLITE_ABORT_ROLLBACK);
+        sqlite3CloseSavepoints(db);
+        db->autoCommit = 1;
+        p->nChange = 0;
+      }
+    }
+  
+    /* If eStatementOp is non-zero, then a statement transaction needs to
+    ** be committed or rolled back. Call sqlite3VdbeCloseStatement() to
+    ** do so. If this operation returns an error, and the current statement
+    ** error code is SQLITE_OK or SQLITE_CONSTRAINT, then promote the
+    ** current statement error code.
+    */
+    if( eStatementOp ){
+      rc = sqlite3VdbeCloseStatement(p, eStatementOp);
+      if( rc ){
+        if( p->rc==SQLITE_OK || (p->rc&0xff)==SQLITE_CONSTRAINT ){
+          p->rc = rc;
+          sqlite3DbFree(db, p->zErrMsg);
+          p->zErrMsg = 0;
+        }
+        sqlite3RollbackAll(db, SQLITE_ABORT_ROLLBACK);
+        sqlite3CloseSavepoints(db);
+        db->autoCommit = 1;
+        p->nChange = 0;
+      }
+    }
+  
+    /* If this was an INSERT, UPDATE or DELETE and no statement transaction
+    ** has been rolled back, update the database connection change-counter. 
+    */
+    if( p->changeCntOn ){
+      if( eStatementOp!=SAVEPOINT_ROLLBACK ){
+        sqlite3VdbeSetChanges(db, p->nChange);
+      }else{
+        sqlite3VdbeSetChanges(db, 0);
+      }
+      p->nChange = 0;
+    }
+
+    /* Release the locks */
+    sqlite3VdbeLeave(p);
+  }
+
+  /* We have successfully halted and closed the VM.  Record this fact. */
+  if( p->pc>=0 ){
+    db->nVdbeActive--;
+    if( !p->readOnly ) db->nVdbeWrite--;
+    if( p->bIsReader ) db->nVdbeRead--;
+    assert( db->nVdbeActive>=db->nVdbeRead );
+    assert( db->nVdbeRead>=db->nVdbeWrite );
+    assert( db->nVdbeWrite>=0 );
+  }
+  p->magic = VDBE_MAGIC_HALT;
+  checkActiveVdbeCnt(db);
+  if( db->mallocFailed ){
+    p->rc = SQLITE_NOMEM_BKPT;
+  }
+
+  /* If the auto-commit flag is set to true, then any locks that were held
+  ** by connection db have now been released. Call sqlite3ConnectionUnlocked() 
+  ** to invoke any required unlock-notify callbacks.
+  */
+  if( db->autoCommit ){
+    sqlite3ConnectionUnlocked(db);
+  }
+
+  assert( db->nVdbeActive>0 || db->autoCommit==0 || db->nStatement==0 );
+  return (p->rc==SQLITE_BUSY ? SQLITE_BUSY : SQLITE_OK);
+}
+
+
+/*
+** Each VDBE holds the result of the most recent sqlite3_step() call
+** in p->rc.  This routine sets that result back to SQLITE_OK.
+*/
+void sqlite3VdbeResetStepResult(Vdbe *p){
+  p->rc = SQLITE_OK;
+}
+
+/*
+** Copy the error code and error message belonging to the VDBE passed
+** as the first argument to its database handle (so that they will be 
+** returned by calls to sqlite3_errcode() and sqlite3_errmsg()).
+**
+** This function does not clear the VDBE error code or message, just
+** copies them to the database handle.
+*/
+int sqlite3VdbeTransferError(Vdbe *p){
+  sqlite3 *db = p->db;
+  int rc = p->rc;
+  if( p->zErrMsg ){
+    db->bBenignMalloc++;
+    sqlite3BeginBenignMalloc();
+    if( db->pErr==0 ) db->pErr = sqlite3ValueNew(db);
+    sqlite3ValueSetStr(db->pErr, -1, p->zErrMsg, SQLITE_UTF8, SQLITE_TRANSIENT);
+    sqlite3EndBenignMalloc();
+    db->bBenignMalloc--;
+    db->errCode = rc;
+  }else{
+    sqlite3Error(db, rc);
+  }
+  return rc;
+}
+
+#ifdef SQLITE_ENABLE_SQLLOG
+/*
+** If an SQLITE_CONFIG_SQLLOG hook is registered and the VM has been run, 
+** invoke it.
+*/
+static void vdbeInvokeSqllog(Vdbe *v){
+  if( sqlite3GlobalConfig.xSqllog && v->rc==SQLITE_OK && v->zSql && v->pc>=0 ){
+    char *zExpanded = sqlite3VdbeExpandSql(v, v->zSql);
+    assert( v->db->init.busy==0 );
+    if( zExpanded ){
+      sqlite3GlobalConfig.xSqllog(
+          sqlite3GlobalConfig.pSqllogArg, v->db, zExpanded, 1
+      );
+      sqlite3DbFree(v->db, zExpanded);
+    }
+  }
+}
+#else
+# define vdbeInvokeSqllog(x)
+#endif
+
+/*
+** Clean up a VDBE after execution but do not delete the VDBE just yet.
+** Write any error messages into *pzErrMsg.  Return the result code.
+**
+** After this routine is run, the VDBE should be ready to be executed
+** again.
+**
+** To look at it another way, this routine resets the state of the
+** virtual machine from VDBE_MAGIC_RUN or VDBE_MAGIC_HALT back to
+** VDBE_MAGIC_INIT.
+*/
+int sqlite3VdbeReset(Vdbe *p){
+  sqlite3 *db;
+  db = p->db;
+
+  /* If the VM did not run to completion or if it encountered an
+  ** error, then it might not have been halted properly.  So halt
+  ** it now.
+  */
+  sqlite3VdbeHalt(p);
+
+  /* If the VDBE has be run even partially, then transfer the error code
+  ** and error message from the VDBE into the main database structure.  But
+  ** if the VDBE has just been set to run but has not actually executed any
+  ** instructions yet, leave the main database error information unchanged.
+  */
+  if( p->pc>=0 ){
+    vdbeInvokeSqllog(p);
+    sqlite3VdbeTransferError(p);
+    sqlite3DbFree(db, p->zErrMsg);
+    p->zErrMsg = 0;
+    if( p->runOnlyOnce ) p->expired = 1;
+  }else if( p->rc && p->expired ){
+    /* The expired flag was set on the VDBE before the first call
+    ** to sqlite3_step(). For consistency (since sqlite3_step() was
+    ** called), set the database error in this case as well.
+    */
+    sqlite3ErrorWithMsg(db, p->rc, p->zErrMsg ? "%s" : 0, p->zErrMsg);
+    sqlite3DbFree(db, p->zErrMsg);
+    p->zErrMsg = 0;
+  }
+
+  /* Reclaim all memory used by the VDBE
+  */
+  Cleanup(p);
+
+  /* Save profiling information from this VDBE run.
+  */
+#ifdef VDBE_PROFILE
+  {
+    FILE *out = fopen("vdbe_profile.out", "a");
+    if( out ){
+      int i;
+      fprintf(out, "---- ");
+      for(i=0; i<p->nOp; i++){
+        fprintf(out, "%02x", p->aOp[i].opcode);
+      }
+      fprintf(out, "\n");
+      if( p->zSql ){
+        char c, pc = 0;
+        fprintf(out, "-- ");
+        for(i=0; (c = p->zSql[i])!=0; i++){
+          if( pc=='\n' ) fprintf(out, "-- ");
+          putc(c, out);
+          pc = c;
+        }
+        if( pc!='\n' ) fprintf(out, "\n");
+      }
+      for(i=0; i<p->nOp; i++){
+        char zHdr[100];
+        sqlite3_snprintf(sizeof(zHdr), zHdr, "%6u %12llu %8llu ",
+           p->aOp[i].cnt,
+           p->aOp[i].cycles,
+           p->aOp[i].cnt>0 ? p->aOp[i].cycles/p->aOp[i].cnt : 0
+        );
+        fprintf(out, "%s", zHdr);
+        sqlite3VdbePrintOp(out, i, &p->aOp[i]);
+      }
+      fclose(out);
+    }
+  }
+#endif
+  p->iCurrentTime = 0;
+  p->magic = VDBE_MAGIC_RESET;
+  return p->rc & db->errMask;
+}
+ 
+/*
+** Clean up and delete a VDBE after execution.  Return an integer which is
+** the result code.  Write any error message text into *pzErrMsg.
+*/
+int sqlite3VdbeFinalize(Vdbe *p){
+  int rc = SQLITE_OK;
+  if( p->magic==VDBE_MAGIC_RUN || p->magic==VDBE_MAGIC_HALT ){
+    rc = sqlite3VdbeReset(p);
+    assert( (rc & p->db->errMask)==rc );
+  }
+  sqlite3VdbeDelete(p);
+  return rc;
+}
+
+/*
+** If parameter iOp is less than zero, then invoke the destructor for
+** all auxiliary data pointers currently cached by the VM passed as
+** the first argument.
+**
+** Or, if iOp is greater than or equal to zero, then the destructor is
+** only invoked for those auxiliary data pointers created by the user 
+** function invoked by the OP_Function opcode at instruction iOp of 
+** VM pVdbe, and only then if:
+**
+**    * the associated function parameter is the 32nd or later (counting
+**      from left to right), or
+**
+**    * the corresponding bit in argument mask is clear (where the first
+**      function parameter corresponds to bit 0 etc.).
+*/
+void sqlite3VdbeDeleteAuxData(sqlite3 *db, AuxData **pp, int iOp, int mask){
+  while( *pp ){
+    AuxData *pAux = *pp;
+    if( (iOp<0)
+     || (pAux->iOp==iOp && (pAux->iArg>31 || !(mask & MASKBIT32(pAux->iArg))))
+    ){
+      testcase( pAux->iArg==31 );
+      if( pAux->xDelete ){
+        pAux->xDelete(pAux->pAux);
+      }
+      *pp = pAux->pNext;
+      sqlite3DbFree(db, pAux);
+    }else{
+      pp= &pAux->pNext;
+    }
+  }
+}
+
+/*
+** Free all memory associated with the Vdbe passed as the second argument,
+** except for object itself, which is preserved.
+**
+** The difference between this function and sqlite3VdbeDelete() is that
+** VdbeDelete() also unlinks the Vdbe from the list of VMs associated with
+** the database connection and frees the object itself.
+*/
+void sqlite3VdbeClearObject(sqlite3 *db, Vdbe *p){
+  SubProgram *pSub, *pNext;
+  assert( p->db==0 || p->db==db );
+  releaseMemArray(p->aColName, p->nResColumn*COLNAME_N);
+  for(pSub=p->pProgram; pSub; pSub=pNext){
+    pNext = pSub->pNext;
+    vdbeFreeOpArray(db, pSub->aOp, pSub->nOp);
+    sqlite3DbFree(db, pSub);
+  }
+  if( p->magic!=VDBE_MAGIC_INIT ){
+    releaseMemArray(p->aVar, p->nVar);
+    sqlite3DbFree(db, p->pVList);
+    sqlite3DbFree(db, p->pFree);
+  }
+  vdbeFreeOpArray(db, p->aOp, p->nOp);
+  sqlite3DbFree(db, p->aColName);
+  sqlite3DbFree(db, p->zSql);
+#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
+  {
+    int i;
+    for(i=0; i<p->nScan; i++){
+      sqlite3DbFree(db, p->aScan[i].zName);
+    }
+    sqlite3DbFree(db, p->aScan);
+  }
+#endif
+}
+
+/*
+** Delete an entire VDBE.
+*/
+void sqlite3VdbeDelete(Vdbe *p){
+  sqlite3 *db;
+
+  if( NEVER(p==0) ) return;
+  db = p->db;
+  assert( sqlite3_mutex_held(db->mutex) );
+  sqlite3VdbeClearObject(db, p);
+  if( p->pPrev ){
+    p->pPrev->pNext = p->pNext;
+  }else{
+    assert( db->pVdbe==p );
+    db->pVdbe = p->pNext;
+  }
+  if( p->pNext ){
+    p->pNext->pPrev = p->pPrev;
+  }
+  p->magic = VDBE_MAGIC_DEAD;
+  p->db = 0;
+  sqlite3DbFree(db, p);
+}
+
+/*
+** The cursor "p" has a pending seek operation that has not yet been
+** carried out.  Seek the cursor now.  If an error occurs, return
+** the appropriate error code.
+*/
+static int SQLITE_NOINLINE handleDeferredMoveto(VdbeCursor *p){
+  int res, rc;
+#ifdef SQLITE_TEST
+  extern int sqlite3_search_count;
+#endif
+  assert( p->deferredMoveto );
+  assert( p->isTable );
+  assert( p->eCurType==CURTYPE_BTREE );
+  rc = sqlite3BtreeMovetoUnpacked(p->uc.pCursor, 0, p->movetoTarget, 0, &res);
+  if( rc ) return rc;
+  if( res!=0 ) return SQLITE_CORRUPT_BKPT;
+#ifdef SQLITE_TEST
+  sqlite3_search_count++;
+#endif
+  p->deferredMoveto = 0;
+  p->cacheStatus = CACHE_STALE;
+  return SQLITE_OK;
+}
+
+/*
+** Something has moved cursor "p" out of place.  Maybe the row it was
+** pointed to was deleted out from under it.  Or maybe the btree was
+** rebalanced.  Whatever the cause, try to restore "p" to the place it
+** is supposed to be pointing.  If the row was deleted out from under the
+** cursor, set the cursor to point to a NULL row.
+*/
+static int SQLITE_NOINLINE handleMovedCursor(VdbeCursor *p){
+  int isDifferentRow, rc;
+  assert( p->eCurType==CURTYPE_BTREE );
+  assert( p->uc.pCursor!=0 );
+  assert( sqlite3BtreeCursorHasMoved(p->uc.pCursor) );
+  rc = sqlite3BtreeCursorRestore(p->uc.pCursor, &isDifferentRow);
+  p->cacheStatus = CACHE_STALE;
+  if( isDifferentRow ) p->nullRow = 1;
+  return rc;
+}
+
+/*
+** Check to ensure that the cursor is valid.  Restore the cursor
+** if need be.  Return any I/O error from the restore operation.
+*/
+int sqlite3VdbeCursorRestore(VdbeCursor *p){
+  assert( p->eCurType==CURTYPE_BTREE );
+  if( sqlite3BtreeCursorHasMoved(p->uc.pCursor) ){
+    return handleMovedCursor(p);
+  }
+  return SQLITE_OK;
+}
+
+/*
+** Make sure the cursor p is ready to read or write the row to which it
+** was last positioned.  Return an error code if an OOM fault or I/O error
+** prevents us from positioning the cursor to its correct position.
+**
+** If a MoveTo operation is pending on the given cursor, then do that
+** MoveTo now.  If no move is pending, check to see if the row has been
+** deleted out from under the cursor and if it has, mark the row as
+** a NULL row.
+**
+** If the cursor is already pointing to the correct row and that row has
+** not been deleted out from under the cursor, then this routine is a no-op.
+*/
+int sqlite3VdbeCursorMoveto(VdbeCursor **pp, int *piCol){
+  VdbeCursor *p = *pp;
+  if( p->eCurType==CURTYPE_BTREE ){
+    if( p->deferredMoveto ){
+      int iMap;
+      if( p->aAltMap && (iMap = p->aAltMap[1+*piCol])>0 ){
+        *pp = p->pAltCursor;
+        *piCol = iMap - 1;
+        return SQLITE_OK;
+      }
+      return handleDeferredMoveto(p);
+    }
+    if( sqlite3BtreeCursorHasMoved(p->uc.pCursor) ){
+      return handleMovedCursor(p);
+    }
+  }
+  return SQLITE_OK;
+}
+
+/*
+** The following functions:
+**
+** sqlite3VdbeSerialType()
+** sqlite3VdbeSerialTypeLen()
+** sqlite3VdbeSerialLen()
+** sqlite3VdbeSerialPut()
+** sqlite3VdbeSerialGet()
+**
+** encapsulate the code that serializes values for storage in SQLite
+** data and index records. Each serialized value consists of a
+** 'serial-type' and a blob of data. The serial type is an 8-byte unsigned
+** integer, stored as a varint.
+**
+** In an SQLite index record, the serial type is stored directly before
+** the blob of data that it corresponds to. In a table record, all serial
+** types are stored at the start of the record, and the blobs of data at
+** the end. Hence these functions allow the caller to handle the
+** serial-type and data blob separately.
+**
+** The following table describes the various storage classes for data:
+**
+**   serial type        bytes of data      type
+**   --------------     ---------------    ---------------
+**      0                     0            NULL
+**      1                     1            signed integer
+**      2                     2            signed integer
+**      3                     3            signed integer
+**      4                     4            signed integer
+**      5                     6            signed integer
+**      6                     8            signed integer
+**      7                     8            IEEE float
+**      8                     0            Integer constant 0
+**      9                     0            Integer constant 1
+**     10,11                               reserved for expansion
+**    N>=12 and even       (N-12)/2        BLOB
+**    N>=13 and odd        (N-13)/2        text
+**
+** The 8 and 9 types were added in 3.3.0, file format 4.  Prior versions
+** of SQLite will not understand those serial types.
+*/
+
+/*
+** Return the serial-type for the value stored in pMem.
+*/
+u32 sqlite3VdbeSerialType(Mem *pMem, int file_format, u32 *pLen){
+  int flags = pMem->flags;
+  u32 n;
+
+  assert( pLen!=0 );
+  if( flags&MEM_Null ){
+    *pLen = 0;
+    return 0;
+  }
+  if( flags&MEM_Int ){
+    /* Figure out whether to use 1, 2, 4, 6 or 8 bytes. */
+#   define MAX_6BYTE ((((i64)0x00008000)<<32)-1)
+    i64 i = pMem->u.i;
+    u64 u;
+    if( i<0 ){
+      u = ~i;
+    }else{
+      u = i;
+    }
+    if( u<=127 ){
+      if( (i&1)==i && file_format>=4 ){
+        *pLen = 0;
+        return 8+(u32)u;
+      }else{
+        *pLen = 1;
+        return 1;
+      }
+    }
+    if( u<=32767 ){ *pLen = 2; return 2; }
+    if( u<=8388607 ){ *pLen = 3; return 3; }
+    if( u<=2147483647 ){ *pLen = 4; return 4; }
+    if( u<=MAX_6BYTE ){ *pLen = 6; return 5; }
+    *pLen = 8;
+    return 6;
+  }
+  if( flags&MEM_Real ){
+    *pLen = 8;
+    return 7;
+  }
+  assert( pMem->db->mallocFailed || flags&(MEM_Str|MEM_Blob) );
+  assert( pMem->n>=0 );
+  n = (u32)pMem->n;
+  if( flags & MEM_Zero ){
+    n += pMem->u.nZero;
+  }
+  *pLen = n;
+  return ((n*2) + 12 + ((flags&MEM_Str)!=0));
+}
+
+/*
+** The sizes for serial types less than 128
+*/
+static const u8 sqlite3SmallTypeSizes[] = {
+        /*  0   1   2   3   4   5   6   7   8   9 */   
+/*   0 */   0,  1,  2,  3,  4,  6,  8,  8,  0,  0,
+/*  10 */   0,  0,  0,  0,  1,  1,  2,  2,  3,  3,
+/*  20 */   4,  4,  5,  5,  6,  6,  7,  7,  8,  8,
+/*  30 */   9,  9, 10, 10, 11, 11, 12, 12, 13, 13,
+/*  40 */  14, 14, 15, 15, 16, 16, 17, 17, 18, 18,
+/*  50 */  19, 19, 20, 20, 21, 21, 22, 22, 23, 23,
+/*  60 */  24, 24, 25, 25, 26, 26, 27, 27, 28, 28,
+/*  70 */  29, 29, 30, 30, 31, 31, 32, 32, 33, 33,
+/*  80 */  34, 34, 35, 35, 36, 36, 37, 37, 38, 38,
+/*  90 */  39, 39, 40, 40, 41, 41, 42, 42, 43, 43,
+/* 100 */  44, 44, 45, 45, 46, 46, 47, 47, 48, 48,
+/* 110 */  49, 49, 50, 50, 51, 51, 52, 52, 53, 53,
+/* 120 */  54, 54, 55, 55, 56, 56, 57, 57
+};
+
+/*
+** Return the length of the data corresponding to the supplied serial-type.
+*/
+u32 sqlite3VdbeSerialTypeLen(u32 serial_type){
+  if( serial_type>=128 ){
+    return (serial_type-12)/2;
+  }else{
+    assert( serial_type<12 
+            || sqlite3SmallTypeSizes[serial_type]==(serial_type - 12)/2 );
+    return sqlite3SmallTypeSizes[serial_type];
+  }
+}
+u8 sqlite3VdbeOneByteSerialTypeLen(u8 serial_type){
+  assert( serial_type<128 );
+  return sqlite3SmallTypeSizes[serial_type];  
+}
+
+/*
+** If we are on an architecture with mixed-endian floating 
+** points (ex: ARM7) then swap the lower 4 bytes with the 
+** upper 4 bytes.  Return the result.
+**
+** For most architectures, this is a no-op.
+**
+** (later):  It is reported to me that the mixed-endian problem
+** on ARM7 is an issue with GCC, not with the ARM7 chip.  It seems
+** that early versions of GCC stored the two words of a 64-bit
+** float in the wrong order.  And that error has been propagated
+** ever since.  The blame is not necessarily with GCC, though.
+** GCC might have just copying the problem from a prior compiler.
+** I am also told that newer versions of GCC that follow a different
+** ABI get the byte order right.
+**
+** Developers using SQLite on an ARM7 should compile and run their
+** application using -DSQLITE_DEBUG=1 at least once.  With DEBUG
+** enabled, some asserts below will ensure that the byte order of
+** floating point values is correct.
+**
+** (2007-08-30)  Frank van Vugt has studied this problem closely
+** and has send his findings to the SQLite developers.  Frank
+** writes that some Linux kernels offer floating point hardware
+** emulation that uses only 32-bit mantissas instead of a full 
+** 48-bits as required by the IEEE standard.  (This is the
+** CONFIG_FPE_FASTFPE option.)  On such systems, floating point
+** byte swapping becomes very complicated.  To avoid problems,
+** the necessary byte swapping is carried out using a 64-bit integer
+** rather than a 64-bit float.  Frank assures us that the code here
+** works for him.  We, the developers, have no way to independently
+** verify this, but Frank seems to know what he is talking about
+** so we trust him.
+*/
+#ifdef SQLITE_MIXED_ENDIAN_64BIT_FLOAT
+static u64 floatSwap(u64 in){
+  union {
+    u64 r;
+    u32 i[2];
+  } u;
+  u32 t;
+
+  u.r = in;
+  t = u.i[0];
+  u.i[0] = u.i[1];
+  u.i[1] = t;
+  return u.r;
+}
+# define swapMixedEndianFloat(X)  X = floatSwap(X)
+#else
+# define swapMixedEndianFloat(X)
+#endif
+
+/*
+** Write the serialized data blob for the value stored in pMem into 
+** buf. It is assumed that the caller has allocated sufficient space.
+** Return the number of bytes written.
+**
+** nBuf is the amount of space left in buf[].  The caller is responsible
+** for allocating enough space to buf[] to hold the entire field, exclusive
+** of the pMem->u.nZero bytes for a MEM_Zero value.
+**
+** Return the number of bytes actually written into buf[].  The number
+** of bytes in the zero-filled tail is included in the return value only
+** if those bytes were zeroed in buf[].
+*/ 
+u32 sqlite3VdbeSerialPut(u8 *buf, Mem *pMem, u32 serial_type){
+  u32 len;
+
+  /* Integer and Real */
+  if( serial_type<=7 && serial_type>0 ){
+    u64 v;
+    u32 i;
+    if( serial_type==7 ){
+      assert( sizeof(v)==sizeof(pMem->u.r) );
+      memcpy(&v, &pMem->u.r, sizeof(v));
+      swapMixedEndianFloat(v);
+    }else{
+      v = pMem->u.i;
+    }
+    len = i = sqlite3SmallTypeSizes[serial_type];
+    assert( i>0 );
+    do{
+      buf[--i] = (u8)(v&0xFF);
+      v >>= 8;
+    }while( i );
+    return len;
+  }
+
+  /* String or blob */
+  if( serial_type>=12 ){
+    assert( pMem->n + ((pMem->flags & MEM_Zero)?pMem->u.nZero:0)
+             == (int)sqlite3VdbeSerialTypeLen(serial_type) );
+    len = pMem->n;
+    if( len>0 ) memcpy(buf, pMem->z, len);
+    return len;
+  }
+
+  /* NULL or constants 0 or 1 */
+  return 0;
+}
+
+/* Input "x" is a sequence of unsigned characters that represent a
+** big-endian integer.  Return the equivalent native integer
+*/
+#define ONE_BYTE_INT(x)    ((i8)(x)[0])
+#define TWO_BYTE_INT(x)    (256*(i8)((x)[0])|(x)[1])
+#define THREE_BYTE_INT(x)  (65536*(i8)((x)[0])|((x)[1]<<8)|(x)[2])
+#define FOUR_BYTE_UINT(x)  (((u32)(x)[0]<<24)|((x)[1]<<16)|((x)[2]<<8)|(x)[3])
+#define FOUR_BYTE_INT(x) (16777216*(i8)((x)[0])|((x)[1]<<16)|((x)[2]<<8)|(x)[3])
+
+/*
+** Deserialize the data blob pointed to by buf as serial type serial_type
+** and store the result in pMem.  Return the number of bytes read.
+**
+** This function is implemented as two separate routines for performance.
+** The few cases that require local variables are broken out into a separate
+** routine so that in most cases the overhead of moving the stack pointer
+** is avoided.
+*/ 
+static u32 SQLITE_NOINLINE serialGet(
+  const unsigned char *buf,     /* Buffer to deserialize from */
+  u32 serial_type,              /* Serial type to deserialize */
+  Mem *pMem                     /* Memory cell to write value into */
+){
+  u64 x = FOUR_BYTE_UINT(buf);
+  u32 y = FOUR_BYTE_UINT(buf+4);
+  x = (x<<32) + y;
+  if( serial_type==6 ){
+    /* EVIDENCE-OF: R-29851-52272 Value is a big-endian 64-bit
+    ** twos-complement integer. */
+    pMem->u.i = *(i64*)&x;
+    pMem->flags = MEM_Int;
+    testcase( pMem->u.i<0 );
+  }else{
+    /* EVIDENCE-OF: R-57343-49114 Value is a big-endian IEEE 754-2008 64-bit
+    ** floating point number. */
+#if !defined(NDEBUG) && !defined(SQLITE_OMIT_FLOATING_POINT)
+    /* Verify that integers and floating point values use the same
+    ** byte order.  Or, that if SQLITE_MIXED_ENDIAN_64BIT_FLOAT is
+    ** defined that 64-bit floating point values really are mixed
+    ** endian.
+    */
+    static const u64 t1 = ((u64)0x3ff00000)<<32;
+    static const double r1 = 1.0;
+    u64 t2 = t1;
+    swapMixedEndianFloat(t2);
+    assert( sizeof(r1)==sizeof(t2) && memcmp(&r1, &t2, sizeof(r1))==0 );
+#endif
+    assert( sizeof(x)==8 && sizeof(pMem->u.r)==8 );
+    swapMixedEndianFloat(x);
+    memcpy(&pMem->u.r, &x, sizeof(x));
+    pMem->flags = sqlite3IsNaN(pMem->u.r) ? MEM_Null : MEM_Real;
+  }
+  return 8;
+}
+u32 sqlite3VdbeSerialGet(
+  const unsigned char *buf,     /* Buffer to deserialize from */
+  u32 serial_type,              /* Serial type to deserialize */
+  Mem *pMem                     /* Memory cell to write value into */
+){
+  switch( serial_type ){
+    case 10:   /* Reserved for future use */
+    case 11:   /* Reserved for future use */
+    case 0: {  /* Null */
+      /* EVIDENCE-OF: R-24078-09375 Value is a NULL. */
+      pMem->flags = MEM_Null;
+      break;
+    }
+    case 1: {
+      /* EVIDENCE-OF: R-44885-25196 Value is an 8-bit twos-complement
+      ** integer. */
+      pMem->u.i = ONE_BYTE_INT(buf);
+      pMem->flags = MEM_Int;
+      testcase( pMem->u.i<0 );
+      return 1;
+    }
+    case 2: { /* 2-byte signed integer */
+      /* EVIDENCE-OF: R-49794-35026 Value is a big-endian 16-bit
+      ** twos-complement integer. */
+      pMem->u.i = TWO_BYTE_INT(buf);
+      pMem->flags = MEM_Int;
+      testcase( pMem->u.i<0 );
+      return 2;
+    }
+    case 3: { /* 3-byte signed integer */
+      /* EVIDENCE-OF: R-37839-54301 Value is a big-endian 24-bit
+      ** twos-complement integer. */
+      pMem->u.i = THREE_BYTE_INT(buf);
+      pMem->flags = MEM_Int;
+      testcase( pMem->u.i<0 );
+      return 3;
+    }
+    case 4: { /* 4-byte signed integer */
+      /* EVIDENCE-OF: R-01849-26079 Value is a big-endian 32-bit
+      ** twos-complement integer. */
+      pMem->u.i = FOUR_BYTE_INT(buf);
+#ifdef __HP_cc 
+      /* Work around a sign-extension bug in the HP compiler for HP/UX */
+      if( buf[0]&0x80 ) pMem->u.i |= 0xffffffff80000000LL;
+#endif
+      pMem->flags = MEM_Int;
+      testcase( pMem->u.i<0 );
+      return 4;
+    }
+    case 5: { /* 6-byte signed integer */
+      /* EVIDENCE-OF: R-50385-09674 Value is a big-endian 48-bit
+      ** twos-complement integer. */
+      pMem->u.i = FOUR_BYTE_UINT(buf+2) + (((i64)1)<<32)*TWO_BYTE_INT(buf);
+      pMem->flags = MEM_Int;
+      testcase( pMem->u.i<0 );
+      return 6;
+    }
+    case 6:   /* 8-byte signed integer */
+    case 7: { /* IEEE floating point */
+      /* These use local variables, so do them in a separate routine
+      ** to avoid having to move the frame pointer in the common case */
+      return serialGet(buf,serial_type,pMem);
+    }
+    case 8:    /* Integer 0 */
+    case 9: {  /* Integer 1 */
+      /* EVIDENCE-OF: R-12976-22893 Value is the integer 0. */
+      /* EVIDENCE-OF: R-18143-12121 Value is the integer 1. */
+      pMem->u.i = serial_type-8;
+      pMem->flags = MEM_Int;
+      return 0;
+    }
+    default: {
+      /* EVIDENCE-OF: R-14606-31564 Value is a BLOB that is (N-12)/2 bytes in
+      ** length.
+      ** EVIDENCE-OF: R-28401-00140 Value is a string in the text encoding and
+      ** (N-13)/2 bytes in length. */
+      static const u16 aFlag[] = { MEM_Blob|MEM_Ephem, MEM_Str|MEM_Ephem };
+      pMem->z = (char *)buf;
+      pMem->n = (serial_type-12)/2;
+      pMem->flags = aFlag[serial_type&1];
+      return pMem->n;
+    }
+  }
+  return 0;
+}
+/*
+** This routine is used to allocate sufficient space for an UnpackedRecord
+** structure large enough to be used with sqlite3VdbeRecordUnpack() if
+** the first argument is a pointer to KeyInfo structure pKeyInfo.
+**
+** The space is either allocated using sqlite3DbMallocRaw() or from within
+** the unaligned buffer passed via the second and third arguments (presumably
+** stack space). If the former, then *ppFree is set to a pointer that should
+** be eventually freed by the caller using sqlite3DbFree(). Or, if the 
+** allocation comes from the pSpace/szSpace buffer, *ppFree is set to NULL
+** before returning.
+**
+** If an OOM error occurs, NULL is returned.
+*/
+UnpackedRecord *sqlite3VdbeAllocUnpackedRecord(
+  KeyInfo *pKeyInfo               /* Description of the record */
+){
+  UnpackedRecord *p;              /* Unpacked record to return */
+  int nByte;                      /* Number of bytes required for *p */
+  nByte = ROUND8(sizeof(UnpackedRecord)) + sizeof(Mem)*(pKeyInfo->nField+1);
+  p = (UnpackedRecord *)sqlite3DbMallocRaw(pKeyInfo->db, nByte);
+  if( !p ) return 0;
+  p->aMem = (Mem*)&((char*)p)[ROUND8(sizeof(UnpackedRecord))];
+  assert( pKeyInfo->aSortOrder!=0 );
+  p->pKeyInfo = pKeyInfo;
+  p->nField = pKeyInfo->nField + 1;
+  return p;
+}
+
+/*
+** Given the nKey-byte encoding of a record in pKey[], populate the 
+** UnpackedRecord structure indicated by the fourth argument with the
+** contents of the decoded record.
+*/ 
+void sqlite3VdbeRecordUnpack(
+  KeyInfo *pKeyInfo,     /* Information about the record format */
+  int nKey,              /* Size of the binary record */
+  const void *pKey,      /* The binary record */
+  UnpackedRecord *p      /* Populate this structure before returning. */
+){
+  const unsigned char *aKey = (const unsigned char *)pKey;
+  int d; 
+  u32 idx;                        /* Offset in aKey[] to read from */
+  u16 u;                          /* Unsigned loop counter */
+  u32 szHdr;
+  Mem *pMem = p->aMem;
+
+  p->default_rc = 0;
+  assert( EIGHT_BYTE_ALIGNMENT(pMem) );
+  idx = getVarint32(aKey, szHdr);
+  d = szHdr;
+  u = 0;
+  while( idx<szHdr && d<=nKey ){
+    u32 serial_type;
+
+    idx += getVarint32(&aKey[idx], serial_type);
+    pMem->enc = pKeyInfo->enc;
+    pMem->db = pKeyInfo->db;
+    /* pMem->flags = 0; // sqlite3VdbeSerialGet() will set this for us */
+    pMem->szMalloc = 0;
+    pMem->z = 0;
+    d += sqlite3VdbeSerialGet(&aKey[d], serial_type, pMem);
+    pMem++;
+    if( (++u)>=p->nField ) break;
+  }
+  assert( u<=pKeyInfo->nField + 1 );
+  p->nField = u;
+}
+
+#if SQLITE_DEBUG
+/*
+** This function compares two index or table record keys in the same way
+** as the sqlite3VdbeRecordCompare() routine. Unlike VdbeRecordCompare(),
+** this function deserializes and compares values using the
+** sqlite3VdbeSerialGet() and sqlite3MemCompare() functions. It is used
+** in assert() statements to ensure that the optimized code in
+** sqlite3VdbeRecordCompare() returns results with these two primitives.
+**
+** Return true if the result of comparison is equivalent to desiredResult.
+** Return false if there is a disagreement.
+*/
+static int vdbeRecordCompareDebug(
+  int nKey1, const void *pKey1, /* Left key */
+  const UnpackedRecord *pPKey2, /* Right key */
+  int desiredResult             /* Correct answer */
+){
+  u32 d1;            /* Offset into aKey[] of next data element */
+  u32 idx1;          /* Offset into aKey[] of next header element */
+  u32 szHdr1;        /* Number of bytes in header */
+  int i = 0;
+  int rc = 0;
+  const unsigned char *aKey1 = (const unsigned char *)pKey1;
+  KeyInfo *pKeyInfo;
+  Mem mem1;
+
+  pKeyInfo = pPKey2->pKeyInfo;
+  if( pKeyInfo->db==0 ) return 1;
+  mem1.enc = pKeyInfo->enc;
+  mem1.db = pKeyInfo->db;
+  /* mem1.flags = 0;  // Will be initialized by sqlite3VdbeSerialGet() */
+  VVA_ONLY( mem1.szMalloc = 0; ) /* Only needed by assert() statements */
+
+  /* Compilers may complain that mem1.u.i is potentially uninitialized.
+  ** We could initialize it, as shown here, to silence those complaints.
+  ** But in fact, mem1.u.i will never actually be used uninitialized, and doing 
+  ** the unnecessary initialization has a measurable negative performance
+  ** impact, since this routine is a very high runner.  And so, we choose
+  ** to ignore the compiler warnings and leave this variable uninitialized.
+  */
+  /*  mem1.u.i = 0;  // not needed, here to silence compiler warning */
+  
+  idx1 = getVarint32(aKey1, szHdr1);
+  if( szHdr1>98307 ) return SQLITE_CORRUPT;
+  d1 = szHdr1;
+  assert( pKeyInfo->nField+pKeyInfo->nXField>=pPKey2->nField || CORRUPT_DB );
+  assert( pKeyInfo->aSortOrder!=0 );
+  assert( pKeyInfo->nField>0 );
+  assert( idx1<=szHdr1 || CORRUPT_DB );
+  do{
+    u32 serial_type1;
+
+    /* Read the serial types for the next element in each key. */
+    idx1 += getVarint32( aKey1+idx1, serial_type1 );
+
+    /* Verify that there is enough key space remaining to avoid
+    ** a buffer overread.  The "d1+serial_type1+2" subexpression will
+    ** always be greater than or equal to the amount of required key space.
+    ** Use that approximation to avoid the more expensive call to
+    ** sqlite3VdbeSerialTypeLen() in the common case.
+    */
+    if( d1+serial_type1+2>(u32)nKey1
+     && d1+sqlite3VdbeSerialTypeLen(serial_type1)>(u32)nKey1 
+    ){
+      break;
+    }
+
+    /* Extract the values to be compared.
+    */
+    d1 += sqlite3VdbeSerialGet(&aKey1[d1], serial_type1, &mem1);
+
+    /* Do the comparison
+    */
+    rc = sqlite3MemCompare(&mem1, &pPKey2->aMem[i], pKeyInfo->aColl[i]);
+    if( rc!=0 ){
+      assert( mem1.szMalloc==0 );  /* See comment below */
+      if( pKeyInfo->aSortOrder[i] ){
+        rc = -rc;  /* Invert the result for DESC sort order. */
+      }
+      goto debugCompareEnd;
+    }
+    i++;
+  }while( idx1<szHdr1 && i<pPKey2->nField );
+
+  /* No memory allocation is ever used on mem1.  Prove this using
+  ** the following assert().  If the assert() fails, it indicates a
+  ** memory leak and a need to call sqlite3VdbeMemRelease(&mem1).
+  */
+  assert( mem1.szMalloc==0 );
+
+  /* rc==0 here means that one of the keys ran out of fields and
+  ** all the fields up to that point were equal. Return the default_rc
+  ** value.  */
+  rc = pPKey2->default_rc;
+
+debugCompareEnd:
+  if( desiredResult==0 && rc==0 ) return 1;
+  if( desiredResult<0 && rc<0 ) return 1;
+  if( desiredResult>0 && rc>0 ) return 1;
+  if( CORRUPT_DB ) return 1;
+  if( pKeyInfo->db->mallocFailed ) return 1;
+  return 0;
+}
+#endif
+
+#if SQLITE_DEBUG
+/*
+** Count the number of fields (a.k.a. columns) in the record given by
+** pKey,nKey.  The verify that this count is less than or equal to the
+** limit given by pKeyInfo->nField + pKeyInfo->nXField.
+**
+** If this constraint is not satisfied, it means that the high-speed
+** vdbeRecordCompareInt() and vdbeRecordCompareString() routines will
+** not work correctly.  If this assert() ever fires, it probably means
+** that the KeyInfo.nField or KeyInfo.nXField values were computed
+** incorrectly.
+*/
+static void vdbeAssertFieldCountWithinLimits(
+  int nKey, const void *pKey,   /* The record to verify */ 
+  const KeyInfo *pKeyInfo       /* Compare size with this KeyInfo */
+){
+  int nField = 0;
+  u32 szHdr;
+  u32 idx;
+  u32 notUsed;
+  const unsigned char *aKey = (const unsigned char*)pKey;
+
+  if( CORRUPT_DB ) return;
+  idx = getVarint32(aKey, szHdr);
+  assert( nKey>=0 );
+  assert( szHdr<=(u32)nKey );
+  while( idx<szHdr ){
+    idx += getVarint32(aKey+idx, notUsed);
+    nField++;
+  }
+  assert( nField <= pKeyInfo->nField+pKeyInfo->nXField );
+}
+#else
+# define vdbeAssertFieldCountWithinLimits(A,B,C)
+#endif
+
+/*
+** Both *pMem1 and *pMem2 contain string values. Compare the two values
+** using the collation sequence pColl. As usual, return a negative , zero
+** or positive value if *pMem1 is less than, equal to or greater than 
+** *pMem2, respectively. Similar in spirit to "rc = (*pMem1) - (*pMem2);".
+*/
+static int vdbeCompareMemString(
+  const Mem *pMem1,
+  const Mem *pMem2,
+  const CollSeq *pColl,
+  u8 *prcErr                      /* If an OOM occurs, set to SQLITE_NOMEM */
+){
+  if( pMem1->enc==pColl->enc ){
+    /* The strings are already in the correct encoding.  Call the
+     ** comparison function directly */
+    return pColl->xCmp(pColl->pUser,pMem1->n,pMem1->z,pMem2->n,pMem2->z);
+  }else{
+    int rc;
+    const void *v1, *v2;
+    int n1, n2;
+    Mem c1;
+    Mem c2;
+    sqlite3VdbeMemInit(&c1, pMem1->db, MEM_Null);
+    sqlite3VdbeMemInit(&c2, pMem1->db, MEM_Null);
+    sqlite3VdbeMemShallowCopy(&c1, pMem1, MEM_Ephem);
+    sqlite3VdbeMemShallowCopy(&c2, pMem2, MEM_Ephem);
+    v1 = sqlite3ValueText((sqlite3_value*)&c1, pColl->enc);
+    n1 = v1==0 ? 0 : c1.n;
+    v2 = sqlite3ValueText((sqlite3_value*)&c2, pColl->enc);
+    n2 = v2==0 ? 0 : c2.n;
+    rc = pColl->xCmp(pColl->pUser, n1, v1, n2, v2);
+    if( (v1==0 || v2==0) && prcErr ) *prcErr = SQLITE_NOMEM_BKPT;
+    sqlite3VdbeMemRelease(&c1);
+    sqlite3VdbeMemRelease(&c2);
+    return rc;
+  }
+}
+
+/*
+** The input pBlob is guaranteed to be a Blob that is not marked
+** with MEM_Zero.  Return true if it could be a zero-blob.
+*/
+static int isAllZero(const char *z, int n){
+  int i;
+  for(i=0; i<n; i++){
+    if( z[i] ) return 0;
+  }
+  return 1;
+}
+
+/*
+** Compare two blobs.  Return negative, zero, or positive if the first
+** is less than, equal to, or greater than the second, respectively.
+** If one blob is a prefix of the other, then the shorter is the lessor.
+*/
+static SQLITE_NOINLINE int sqlite3BlobCompare(const Mem *pB1, const Mem *pB2){
+  int c;
+  int n1 = pB1->n;
+  int n2 = pB2->n;
+
+  /* It is possible to have a Blob value that has some non-zero content
+  ** followed by zero content.  But that only comes up for Blobs formed
+  ** by the OP_MakeRecord opcode, and such Blobs never get passed into
+  ** sqlite3MemCompare(). */
+  assert( (pB1->flags & MEM_Zero)==0 || n1==0 );
+  assert( (pB2->flags & MEM_Zero)==0 || n2==0 );
+
+  if( (pB1->flags|pB2->flags) & MEM_Zero ){
+    if( pB1->flags & pB2->flags & MEM_Zero ){
+      return pB1->u.nZero - pB2->u.nZero;
+    }else if( pB1->flags & MEM_Zero ){
+      if( !isAllZero(pB2->z, pB2->n) ) return -1;
+      return pB1->u.nZero - n2;
+    }else{
+      if( !isAllZero(pB1->z, pB1->n) ) return +1;
+      return n1 - pB2->u.nZero;
+    }
+  }
+  c = memcmp(pB1->z, pB2->z, n1>n2 ? n2 : n1);
+  if( c ) return c;
+  return n1 - n2;
+}
+
+/*
+** Do a comparison between a 64-bit signed integer and a 64-bit floating-point
+** number.  Return negative, zero, or positive if the first (i64) is less than,
+** equal to, or greater than the second (double).
+*/
+static int sqlite3IntFloatCompare(i64 i, double r){
+  if( sizeof(LONGDOUBLE_TYPE)>8 ){
+    LONGDOUBLE_TYPE x = (LONGDOUBLE_TYPE)i;
+    if( x<r ) return -1;
+    if( x>r ) return +1;
+    return 0;
+  }else{
+    i64 y;
+    double s;
+    if( r<-9223372036854775808.0 ) return +1;
+    if( r>9223372036854775807.0 ) return -1;
+    y = (i64)r;
+    if( i<y ) return -1;
+    if( i>y ){
+      if( y==SMALLEST_INT64 && r>0.0 ) return -1;
+      return +1;
+    }
+    s = (double)i;
+    if( s<r ) return -1;
+    if( s>r ) return +1;
+    return 0;
+  }
+}
+
+/*
+** Compare the values contained by the two memory cells, returning
+** negative, zero or positive if pMem1 is less than, equal to, or greater
+** than pMem2. Sorting order is NULL's first, followed by numbers (integers
+** and reals) sorted numerically, followed by text ordered by the collating
+** sequence pColl and finally blob's ordered by memcmp().
+**
+** Two NULL values are considered equal by this function.
+*/
+int sqlite3MemCompare(const Mem *pMem1, const Mem *pMem2, const CollSeq *pColl){
+  int f1, f2;
+  int combined_flags;
+
+  f1 = pMem1->flags;
+  f2 = pMem2->flags;
+  combined_flags = f1|f2;
+  assert( (combined_flags & MEM_RowSet)==0 );
+ 
+  /* If one value is NULL, it is less than the other. If both values
+  ** are NULL, return 0.
+  */
+  if( combined_flags&MEM_Null ){
+    return (f2&MEM_Null) - (f1&MEM_Null);
+  }
+
+  /* At least one of the two values is a number
+  */
+  if( combined_flags&(MEM_Int|MEM_Real) ){
+    if( (f1 & f2 & MEM_Int)!=0 ){
+      if( pMem1->u.i < pMem2->u.i ) return -1;
+      if( pMem1->u.i > pMem2->u.i ) return +1;
+      return 0;
+    }
+    if( (f1 & f2 & MEM_Real)!=0 ){
+      if( pMem1->u.r < pMem2->u.r ) return -1;
+      if( pMem1->u.r > pMem2->u.r ) return +1;
+      return 0;
+    }
+    if( (f1&MEM_Int)!=0 ){
+      if( (f2&MEM_Real)!=0 ){
+        return sqlite3IntFloatCompare(pMem1->u.i, pMem2->u.r);
+      }else{
+        return -1;
+      }
+    }
+    if( (f1&MEM_Real)!=0 ){
+      if( (f2&MEM_Int)!=0 ){
+        return -sqlite3IntFloatCompare(pMem2->u.i, pMem1->u.r);
+      }else{
+        return -1;
+      }
+    }
+    return +1;
+  }
+
+  /* If one value is a string and the other is a blob, the string is less.
+  ** If both are strings, compare using the collating functions.
+  */
+  if( combined_flags&MEM_Str ){
+    if( (f1 & MEM_Str)==0 ){
+      return 1;
+    }
+    if( (f2 & MEM_Str)==0 ){
+      return -1;
+    }
+
+    assert( pMem1->enc==pMem2->enc || pMem1->db->mallocFailed );
+    assert( pMem1->enc==SQLITE_UTF8 || 
+            pMem1->enc==SQLITE_UTF16LE || pMem1->enc==SQLITE_UTF16BE );
+
+    /* The collation sequence must be defined at this point, even if
+    ** the user deletes the collation sequence after the vdbe program is
+    ** compiled (this was not always the case).
+    */
+    assert( !pColl || pColl->xCmp );
+
+    if( pColl ){
+      return vdbeCompareMemString(pMem1, pMem2, pColl, 0);
+    }
+    /* If a NULL pointer was passed as the collate function, fall through
+    ** to the blob case and use memcmp().  */
+  }
+ 
+  /* Both values must be blobs.  Compare using memcmp().  */
+  return sqlite3BlobCompare(pMem1, pMem2);
+}
+
+
+/*
+** The first argument passed to this function is a serial-type that
+** corresponds to an integer - all values between 1 and 9 inclusive 
+** except 7. The second points to a buffer containing an integer value
+** serialized according to serial_type. This function deserializes
+** and returns the value.
+*/
+static i64 vdbeRecordDecodeInt(u32 serial_type, const u8 *aKey){
+  u32 y;
+  assert( CORRUPT_DB || (serial_type>=1 && serial_type<=9 && serial_type!=7) );
+  switch( serial_type ){
+    case 0:
+    case 1:
+      testcase( aKey[0]&0x80 );
+      return ONE_BYTE_INT(aKey);
+    case 2:
+      testcase( aKey[0]&0x80 );
+      return TWO_BYTE_INT(aKey);
+    case 3:
+      testcase( aKey[0]&0x80 );
+      return THREE_BYTE_INT(aKey);
+    case 4: {
+      testcase( aKey[0]&0x80 );
+      y = FOUR_BYTE_UINT(aKey);
+      return (i64)*(int*)&y;
+    }
+    case 5: {
+      testcase( aKey[0]&0x80 );
+      return FOUR_BYTE_UINT(aKey+2) + (((i64)1)<<32)*TWO_BYTE_INT(aKey);
+    }
+    case 6: {
+      u64 x = FOUR_BYTE_UINT(aKey);
+      testcase( aKey[0]&0x80 );
+      x = (x<<32) | FOUR_BYTE_UINT(aKey+4);
+      return (i64)*(i64*)&x;
+    }
+  }
+
+  return (serial_type - 8);
+}
+
+/*
+** This function compares the two table rows or index records
+** specified by {nKey1, pKey1} and pPKey2.  It returns a negative, zero
+** or positive integer if key1 is less than, equal to or 
+** greater than key2.  The {nKey1, pKey1} key must be a blob
+** created by the OP_MakeRecord opcode of the VDBE.  The pPKey2
+** key must be a parsed key such as obtained from
+** sqlite3VdbeParseRecord.
+**
+** If argument bSkip is non-zero, it is assumed that the caller has already
+** determined that the first fields of the keys are equal.
+**
+** Key1 and Key2 do not have to contain the same number of fields. If all 
+** fields that appear in both keys are equal, then pPKey2->default_rc is 
+** returned.
+**
+** If database corruption is discovered, set pPKey2->errCode to 
+** SQLITE_CORRUPT and return 0. If an OOM error is encountered, 
+** pPKey2->errCode is set to SQLITE_NOMEM and, if it is not NULL, the
+** malloc-failed flag set on database handle (pPKey2->pKeyInfo->db).
+*/
+int sqlite3VdbeRecordCompareWithSkip(
+  int nKey1, const void *pKey1,   /* Left key */
+  UnpackedRecord *pPKey2,         /* Right key */
+  int bSkip                       /* If true, skip the first field */
+){
+  u32 d1;                         /* Offset into aKey[] of next data element */
+  int i;                          /* Index of next field to compare */
+  u32 szHdr1;                     /* Size of record header in bytes */
+  u32 idx1;                       /* Offset of first type in header */
+  int rc = 0;                     /* Return value */
+  Mem *pRhs = pPKey2->aMem;       /* Next field of pPKey2 to compare */
+  KeyInfo *pKeyInfo = pPKey2->pKeyInfo;
+  const unsigned char *aKey1 = (const unsigned char *)pKey1;
+  Mem mem1;
+
+  /* If bSkip is true, then the caller has already determined that the first
+  ** two elements in the keys are equal. Fix the various stack variables so
+  ** that this routine begins comparing at the second field. */
+  if( bSkip ){
+    u32 s1;
+    idx1 = 1 + getVarint32(&aKey1[1], s1);
+    szHdr1 = aKey1[0];
+    d1 = szHdr1 + sqlite3VdbeSerialTypeLen(s1);
+    i = 1;
+    pRhs++;
+  }else{
+    idx1 = getVarint32(aKey1, szHdr1);
+    d1 = szHdr1;
+    if( d1>(unsigned)nKey1 ){ 
+      pPKey2->errCode = (u8)SQLITE_CORRUPT_BKPT;
+      return 0;  /* Corruption */
+    }
+    i = 0;
+  }
+
+  VVA_ONLY( mem1.szMalloc = 0; ) /* Only needed by assert() statements */
+  assert( pPKey2->pKeyInfo->nField+pPKey2->pKeyInfo->nXField>=pPKey2->nField 
+       || CORRUPT_DB );
+  assert( pPKey2->pKeyInfo->aSortOrder!=0 );
+  assert( pPKey2->pKeyInfo->nField>0 );
+  assert( idx1<=szHdr1 || CORRUPT_DB );
+  do{
+    u32 serial_type;
+
+    /* RHS is an integer */
+    if( pRhs->flags & MEM_Int ){
+      serial_type = aKey1[idx1];
+      testcase( serial_type==12 );
+      if( serial_type>=10 ){
+        rc = +1;
+      }else if( serial_type==0 ){
+        rc = -1;
+      }else if( serial_type==7 ){
+        sqlite3VdbeSerialGet(&aKey1[d1], serial_type, &mem1);
+        rc = -sqlite3IntFloatCompare(pRhs->u.i, mem1.u.r);
+      }else{
+        i64 lhs = vdbeRecordDecodeInt(serial_type, &aKey1[d1]);
+        i64 rhs = pRhs->u.i;
+        if( lhs<rhs ){
+          rc = -1;
+        }else if( lhs>rhs ){
+          rc = +1;
+        }
+      }
+    }
+
+    /* RHS is real */
+    else if( pRhs->flags & MEM_Real ){
+      serial_type = aKey1[idx1];
+      if( serial_type>=10 ){
+        /* Serial types 12 or greater are strings and blobs (greater than
+        ** numbers). Types 10 and 11 are currently "reserved for future 
+        ** use", so it doesn't really matter what the results of comparing
+        ** them to numberic values are.  */
+        rc = +1;
+      }else if( serial_type==0 ){
+        rc = -1;
+      }else{
+        sqlite3VdbeSerialGet(&aKey1[d1], serial_type, &mem1);
+        if( serial_type==7 ){
+          if( mem1.u.r<pRhs->u.r ){
+            rc = -1;
+          }else if( mem1.u.r>pRhs->u.r ){
+            rc = +1;
+          }
+        }else{
+          rc = sqlite3IntFloatCompare(mem1.u.i, pRhs->u.r);
+        }
+      }
+    }
+
+    /* RHS is a string */
+    else if( pRhs->flags & MEM_Str ){
+      getVarint32(&aKey1[idx1], serial_type);
+      testcase( serial_type==12 );
+      if( serial_type<12 ){
+        rc = -1;
+      }else if( !(serial_type & 0x01) ){
+        rc = +1;
+      }else{
+        mem1.n = (serial_type - 12) / 2;
+        testcase( (d1+mem1.n)==(unsigned)nKey1 );
+        testcase( (d1+mem1.n+1)==(unsigned)nKey1 );
+        if( (d1+mem1.n) > (unsigned)nKey1 ){
+          pPKey2->errCode = (u8)SQLITE_CORRUPT_BKPT;
+          return 0;                /* Corruption */
+        }else if( pKeyInfo->aColl[i] ){
+          mem1.enc = pKeyInfo->enc;
+          mem1.db = pKeyInfo->db;
+          mem1.flags = MEM_Str;
+          mem1.z = (char*)&aKey1[d1];
+          rc = vdbeCompareMemString(
+              &mem1, pRhs, pKeyInfo->aColl[i], &pPKey2->errCode
+          );
+        }else{
+          int nCmp = MIN(mem1.n, pRhs->n);
+          rc = memcmp(&aKey1[d1], pRhs->z, nCmp);
+          if( rc==0 ) rc = mem1.n - pRhs->n; 
+        }
+      }
+    }
+
+    /* RHS is a blob */
+    else if( pRhs->flags & MEM_Blob ){
+      assert( (pRhs->flags & MEM_Zero)==0 || pRhs->n==0 );
+      getVarint32(&aKey1[idx1], serial_type);
+      testcase( serial_type==12 );
+      if( serial_type<12 || (serial_type & 0x01) ){
+        rc = -1;
+      }else{
+        int nStr = (serial_type - 12) / 2;
+        testcase( (d1+nStr)==(unsigned)nKey1 );
+        testcase( (d1+nStr+1)==(unsigned)nKey1 );
+        if( (d1+nStr) > (unsigned)nKey1 ){
+          pPKey2->errCode = (u8)SQLITE_CORRUPT_BKPT;
+          return 0;                /* Corruption */
+        }else if( pRhs->flags & MEM_Zero ){
+          if( !isAllZero((const char*)&aKey1[d1],nStr) ){
+            rc = 1;
+          }else{
+            rc = nStr - pRhs->u.nZero;
+          }
+        }else{
+          int nCmp = MIN(nStr, pRhs->n);
+          rc = memcmp(&aKey1[d1], pRhs->z, nCmp);
+          if( rc==0 ) rc = nStr - pRhs->n;
+        }
+      }
+    }
+
+    /* RHS is null */
+    else{
+      serial_type = aKey1[idx1];
+      rc = (serial_type!=0);
+    }
+
+    if( rc!=0 ){
+      if( pKeyInfo->aSortOrder[i] ){
+        rc = -rc;
+      }
+      assert( vdbeRecordCompareDebug(nKey1, pKey1, pPKey2, rc) );
+      assert( mem1.szMalloc==0 );  /* See comment below */
+      return rc;
+    }
+
+    i++;
+    pRhs++;
+    d1 += sqlite3VdbeSerialTypeLen(serial_type);
+    idx1 += sqlite3VarintLen(serial_type);
+  }while( idx1<(unsigned)szHdr1 && i<pPKey2->nField && d1<=(unsigned)nKey1 );
+
+  /* No memory allocation is ever used on mem1.  Prove this using
+  ** the following assert().  If the assert() fails, it indicates a
+  ** memory leak and a need to call sqlite3VdbeMemRelease(&mem1).  */
+  assert( mem1.szMalloc==0 );
+
+  /* rc==0 here means that one or both of the keys ran out of fields and
+  ** all the fields up to that point were equal. Return the default_rc
+  ** value.  */
+  assert( CORRUPT_DB 
+       || vdbeRecordCompareDebug(nKey1, pKey1, pPKey2, pPKey2->default_rc) 
+       || pKeyInfo->db->mallocFailed
+  );
+  pPKey2->eqSeen = 1;
+  return pPKey2->default_rc;
+}
+int sqlite3VdbeRecordCompare(
+  int nKey1, const void *pKey1,   /* Left key */
+  UnpackedRecord *pPKey2          /* Right key */
+){
+  return sqlite3VdbeRecordCompareWithSkip(nKey1, pKey1, pPKey2, 0);
+}
+
+
+/*
+** This function is an optimized version of sqlite3VdbeRecordCompare() 
+** that (a) the first field of pPKey2 is an integer, and (b) the 
+** size-of-header varint at the start of (pKey1/nKey1) fits in a single
+** byte (i.e. is less than 128).
+**
+** To avoid concerns about buffer overreads, this routine is only used
+** on schemas where the maximum valid header size is 63 bytes or less.
+*/
+static int vdbeRecordCompareInt(
+  int nKey1, const void *pKey1, /* Left key */
+  UnpackedRecord *pPKey2        /* Right key */
+){
+  const u8 *aKey = &((const u8*)pKey1)[*(const u8*)pKey1 & 0x3F];
+  int serial_type = ((const u8*)pKey1)[1];
+  int res;
+  u32 y;
+  u64 x;
+  i64 v;
+  i64 lhs;
+
+  vdbeAssertFieldCountWithinLimits(nKey1, pKey1, pPKey2->pKeyInfo);
+  assert( (*(u8*)pKey1)<=0x3F || CORRUPT_DB );
+  switch( serial_type ){
+    case 1: { /* 1-byte signed integer */
+      lhs = ONE_BYTE_INT(aKey);
+      testcase( lhs<0 );
+      break;
+    }
+    case 2: { /* 2-byte signed integer */
+      lhs = TWO_BYTE_INT(aKey);
+      testcase( lhs<0 );
+      break;
+    }
+    case 3: { /* 3-byte signed integer */
+      lhs = THREE_BYTE_INT(aKey);
+      testcase( lhs<0 );
+      break;
+    }
+    case 4: { /* 4-byte signed integer */
+      y = FOUR_BYTE_UINT(aKey);
+      lhs = (i64)*(int*)&y;
+      testcase( lhs<0 );
+      break;
+    }
+    case 5: { /* 6-byte signed integer */
+      lhs = FOUR_BYTE_UINT(aKey+2) + (((i64)1)<<32)*TWO_BYTE_INT(aKey);
+      testcase( lhs<0 );
+      break;
+    }
+    case 6: { /* 8-byte signed integer */
+      x = FOUR_BYTE_UINT(aKey);
+      x = (x<<32) | FOUR_BYTE_UINT(aKey+4);
+      lhs = *(i64*)&x;
+      testcase( lhs<0 );
+      break;
+    }
+    case 8: 
+      lhs = 0;
+      break;
+    case 9:
+      lhs = 1;
+      break;
+
+    /* This case could be removed without changing the results of running
+    ** this code. Including it causes gcc to generate a faster switch 
+    ** statement (since the range of switch targets now starts at zero and
+    ** is contiguous) but does not cause any duplicate code to be generated
+    ** (as gcc is clever enough to combine the two like cases). Other 
+    ** compilers might be similar.  */ 
+    case 0: case 7:
+      return sqlite3VdbeRecordCompare(nKey1, pKey1, pPKey2);
+
+    default:
+      return sqlite3VdbeRecordCompare(nKey1, pKey1, pPKey2);
+  }
+
+  v = pPKey2->aMem[0].u.i;
+  if( v>lhs ){
+    res = pPKey2->r1;
+  }else if( v<lhs ){
+    res = pPKey2->r2;
+  }else if( pPKey2->nField>1 ){
+    /* The first fields of the two keys are equal. Compare the trailing 
+    ** fields.  */
+    res = sqlite3VdbeRecordCompareWithSkip(nKey1, pKey1, pPKey2, 1);
+  }else{
+    /* The first fields of the two keys are equal and there are no trailing
+    ** fields. Return pPKey2->default_rc in this case. */
+    res = pPKey2->default_rc;
+    pPKey2->eqSeen = 1;
+  }
+
+  assert( vdbeRecordCompareDebug(nKey1, pKey1, pPKey2, res) );
+  return res;
+}
+
+/*
+** This function is an optimized version of sqlite3VdbeRecordCompare() 
+** that (a) the first field of pPKey2 is a string, that (b) the first field
+** uses the collation sequence BINARY and (c) that the size-of-header varint 
+** at the start of (pKey1/nKey1) fits in a single byte.
+*/
+static int vdbeRecordCompareString(
+  int nKey1, const void *pKey1, /* Left key */
+  UnpackedRecord *pPKey2        /* Right key */
+){
+  const u8 *aKey1 = (const u8*)pKey1;
+  int serial_type;
+  int res;
+
+  assert( pPKey2->aMem[0].flags & MEM_Str );
+  vdbeAssertFieldCountWithinLimits(nKey1, pKey1, pPKey2->pKeyInfo);
+  getVarint32(&aKey1[1], serial_type);
+  if( serial_type<12 ){
+    res = pPKey2->r1;      /* (pKey1/nKey1) is a number or a null */
+  }else if( !(serial_type & 0x01) ){ 
+    res = pPKey2->r2;      /* (pKey1/nKey1) is a blob */
+  }else{
+    int nCmp;
+    int nStr;
+    int szHdr = aKey1[0];
+
+    nStr = (serial_type-12) / 2;
+    if( (szHdr + nStr) > nKey1 ){
+      pPKey2->errCode = (u8)SQLITE_CORRUPT_BKPT;
+      return 0;    /* Corruption */
+    }
+    nCmp = MIN( pPKey2->aMem[0].n, nStr );
+    res = memcmp(&aKey1[szHdr], pPKey2->aMem[0].z, nCmp);
+
+    if( res==0 ){
+      res = nStr - pPKey2->aMem[0].n;
+      if( res==0 ){
+        if( pPKey2->nField>1 ){
+          res = sqlite3VdbeRecordCompareWithSkip(nKey1, pKey1, pPKey2, 1);
+        }else{
+          res = pPKey2->default_rc;
+          pPKey2->eqSeen = 1;
+        }
+      }else if( res>0 ){
+        res = pPKey2->r2;
+      }else{
+        res = pPKey2->r1;
+      }
+    }else if( res>0 ){
+      res = pPKey2->r2;
+    }else{
+      res = pPKey2->r1;
+    }
+  }
+
+  assert( vdbeRecordCompareDebug(nKey1, pKey1, pPKey2, res)
+       || CORRUPT_DB
+       || pPKey2->pKeyInfo->db->mallocFailed
+  );
+  return res;
+}
+
+/*
+** Return a pointer to an sqlite3VdbeRecordCompare() compatible function
+** suitable for comparing serialized records to the unpacked record passed
+** as the only argument.
+*/
+RecordCompare sqlite3VdbeFindCompare(UnpackedRecord *p){
+  /* varintRecordCompareInt() and varintRecordCompareString() both assume
+  ** that the size-of-header varint that occurs at the start of each record
+  ** fits in a single byte (i.e. is 127 or less). varintRecordCompareInt()
+  ** also assumes that it is safe to overread a buffer by at least the 
+  ** maximum possible legal header size plus 8 bytes. Because there is
+  ** guaranteed to be at least 74 (but not 136) bytes of padding following each
+  ** buffer passed to varintRecordCompareInt() this makes it convenient to
+  ** limit the size of the header to 64 bytes in cases where the first field
+  ** is an integer.
+  **
+  ** The easiest way to enforce this limit is to consider only records with
+  ** 13 fields or less. If the first field is an integer, the maximum legal
+  ** header size is (12*5 + 1 + 1) bytes.  */
+  if( (p->pKeyInfo->nField + p->pKeyInfo->nXField)<=13 ){
+    int flags = p->aMem[0].flags;
+    if( p->pKeyInfo->aSortOrder[0] ){
+      p->r1 = 1;
+      p->r2 = -1;
+    }else{
+      p->r1 = -1;
+      p->r2 = 1;
+    }
+    if( (flags & MEM_Int) ){
+      return vdbeRecordCompareInt;
+    }
+    testcase( flags & MEM_Real );
+    testcase( flags & MEM_Null );
+    testcase( flags & MEM_Blob );
+    if( (flags & (MEM_Real|MEM_Null|MEM_Blob))==0 && p->pKeyInfo->aColl[0]==0 ){
+      assert( flags & MEM_Str );
+      return vdbeRecordCompareString;
+    }
+  }
+
+  return sqlite3VdbeRecordCompare;
+}
+
+/*
+** pCur points at an index entry created using the OP_MakeRecord opcode.
+** Read the rowid (the last field in the record) and store it in *rowid.
+** Return SQLITE_OK if everything works, or an error code otherwise.
+**
+** pCur might be pointing to text obtained from a corrupt database file.
+** So the content cannot be trusted.  Do appropriate checks on the content.
+*/
+int sqlite3VdbeIdxRowid(sqlite3 *db, BtCursor *pCur, i64 *rowid){
+  i64 nCellKey = 0;
+  int rc;
+  u32 szHdr;        /* Size of the header */
+  u32 typeRowid;    /* Serial type of the rowid */
+  u32 lenRowid;     /* Size of the rowid */
+  Mem m, v;
+
+  /* Get the size of the index entry.  Only indices entries of less
+  ** than 2GiB are support - anything large must be database corruption.
+  ** Any corruption is detected in sqlite3BtreeParseCellPtr(), though, so
+  ** this code can safely assume that nCellKey is 32-bits  
+  */
+  assert( sqlite3BtreeCursorIsValid(pCur) );
+  nCellKey = sqlite3BtreePayloadSize(pCur);
+  assert( (nCellKey & SQLITE_MAX_U32)==(u64)nCellKey );
+
+  /* Read in the complete content of the index entry */
+  sqlite3VdbeMemInit(&m, db, 0);
+  rc = sqlite3VdbeMemFromBtree(pCur, 0, (u32)nCellKey, &m);
+  if( rc ){
+    return rc;
+  }
+
+  /* The index entry must begin with a header size */
+  (void)getVarint32((u8*)m.z, szHdr);
+  testcase( szHdr==3 );
+  testcase( szHdr==m.n );
+  if( unlikely(szHdr<3 || (int)szHdr>m.n) ){
+    goto idx_rowid_corruption;
+  }
+
+  /* The last field of the index should be an integer - the ROWID.
+  ** Verify that the last entry really is an integer. */
+  (void)getVarint32((u8*)&m.z[szHdr-1], typeRowid);
+  testcase( typeRowid==1 );
+  testcase( typeRowid==2 );
+  testcase( typeRowid==3 );
+  testcase( typeRowid==4 );
+  testcase( typeRowid==5 );
+  testcase( typeRowid==6 );
+  testcase( typeRowid==8 );
+  testcase( typeRowid==9 );
+  if( unlikely(typeRowid<1 || typeRowid>9 || typeRowid==7) ){
+    goto idx_rowid_corruption;
+  }
+  lenRowid = sqlite3SmallTypeSizes[typeRowid];
+  testcase( (u32)m.n==szHdr+lenRowid );
+  if( unlikely((u32)m.n<szHdr+lenRowid) ){
+    goto idx_rowid_corruption;
+  }
+
+  /* Fetch the integer off the end of the index record */
+  sqlite3VdbeSerialGet((u8*)&m.z[m.n-lenRowid], typeRowid, &v);
+  *rowid = v.u.i;
+  sqlite3VdbeMemRelease(&m);
+  return SQLITE_OK;
+
+  /* Jump here if database corruption is detected after m has been
+  ** allocated.  Free the m object and return SQLITE_CORRUPT. */
+idx_rowid_corruption:
+  testcase( m.szMalloc!=0 );
+  sqlite3VdbeMemRelease(&m);
+  return SQLITE_CORRUPT_BKPT;
+}
+
+/*
+** Compare the key of the index entry that cursor pC is pointing to against
+** the key string in pUnpacked.  Write into *pRes a number
+** that is negative, zero, or positive if pC is less than, equal to,
+** or greater than pUnpacked.  Return SQLITE_OK on success.
+**
+** pUnpacked is either created without a rowid or is truncated so that it
+** omits the rowid at the end.  The rowid at the end of the index entry
+** is ignored as well.  Hence, this routine only compares the prefixes 
+** of the keys prior to the final rowid, not the entire key.
+*/
+int sqlite3VdbeIdxKeyCompare(
+  sqlite3 *db,                     /* Database connection */
+  VdbeCursor *pC,                  /* The cursor to compare against */
+  UnpackedRecord *pUnpacked,       /* Unpacked version of key */
+  int *res                         /* Write the comparison result here */
+){
+  i64 nCellKey = 0;
+  int rc;
+  BtCursor *pCur;
+  Mem m;
+
+  assert( pC->eCurType==CURTYPE_BTREE );
+  pCur = pC->uc.pCursor;
+  assert( sqlite3BtreeCursorIsValid(pCur) );
+  nCellKey = sqlite3BtreePayloadSize(pCur);
+  /* nCellKey will always be between 0 and 0xffffffff because of the way
+  ** that btreeParseCellPtr() and sqlite3GetVarint32() are implemented */
+  if( nCellKey<=0 || nCellKey>0x7fffffff ){
+    *res = 0;
+    return SQLITE_CORRUPT_BKPT;
+  }
+  sqlite3VdbeMemInit(&m, db, 0);
+  rc = sqlite3VdbeMemFromBtree(pCur, 0, (u32)nCellKey, &m);
+  if( rc ){
+    return rc;
+  }
+  *res = sqlite3VdbeRecordCompare(m.n, m.z, pUnpacked);
+  sqlite3VdbeMemRelease(&m);
+  return SQLITE_OK;
+}
+
+/*
+** This routine sets the value to be returned by subsequent calls to
+** sqlite3_changes() on the database handle 'db'. 
+*/
+void sqlite3VdbeSetChanges(sqlite3 *db, int nChange){
+  assert( sqlite3_mutex_held(db->mutex) );
+  db->nChange = nChange;
+  db->nTotalChange += nChange;
+}
+
+/*
+** Set a flag in the vdbe to update the change counter when it is finalised
+** or reset.
+*/
+void sqlite3VdbeCountChanges(Vdbe *v){
+  v->changeCntOn = 1;
+}
+
+/*
+** Mark every prepared statement associated with a database connection
+** as expired.
+**
+** An expired statement means that recompilation of the statement is
+** recommend.  Statements expire when things happen that make their
+** programs obsolete.  Removing user-defined functions or collating
+** sequences, or changing an authorization function are the types of
+** things that make prepared statements obsolete.
+*/
+void sqlite3ExpirePreparedStatements(sqlite3 *db){
+  Vdbe *p;
+  for(p = db->pVdbe; p; p=p->pNext){
+    p->expired = 1;
+  }
+}
+
+/*
+** Return the database associated with the Vdbe.
+*/
+sqlite3 *sqlite3VdbeDb(Vdbe *v){
+  return v->db;
+}
+
+/*
+** Return a pointer to an sqlite3_value structure containing the value bound
+** parameter iVar of VM v. Except, if the value is an SQL NULL, return 
+** 0 instead. Unless it is NULL, apply affinity aff (one of the SQLITE_AFF_*
+** constants) to the value before returning it.
+**
+** The returned value must be freed by the caller using sqlite3ValueFree().
+*/
+sqlite3_value *sqlite3VdbeGetBoundValue(Vdbe *v, int iVar, u8 aff){
+  assert( iVar>0 );
+  if( v ){
+    Mem *pMem = &v->aVar[iVar-1];
+    if( 0==(pMem->flags & MEM_Null) ){
+      sqlite3_value *pRet = sqlite3ValueNew(v->db);
+      if( pRet ){
+        sqlite3VdbeMemCopy((Mem *)pRet, pMem);
+        sqlite3ValueApplyAffinity(pRet, aff, SQLITE_UTF8);
+      }
+      return pRet;
+    }
+  }
+  return 0;
+}
+
+/*
+** Configure SQL variable iVar so that binding a new value to it signals
+** to sqlite3_reoptimize() that re-preparing the statement may result
+** in a better query plan.
+*/
+void sqlite3VdbeSetVarmask(Vdbe *v, int iVar){
+  assert( iVar>0 );
+  if( iVar>32 ){
+    v->expmask = 0xffffffff;
+  }else{
+    v->expmask |= ((u32)1 << (iVar-1));
+  }
+}
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+/*
+** Transfer error message text from an sqlite3_vtab.zErrMsg (text stored
+** in memory obtained from sqlite3_malloc) into a Vdbe.zErrMsg (text stored
+** in memory obtained from sqlite3DbMalloc).
+*/
+void sqlite3VtabImportErrmsg(Vdbe *p, sqlite3_vtab *pVtab){
+  if( pVtab->zErrMsg ){
+    sqlite3 *db = p->db;
+    sqlite3DbFree(db, p->zErrMsg);
+    p->zErrMsg = sqlite3DbStrDup(db, pVtab->zErrMsg);
+    sqlite3_free(pVtab->zErrMsg);
+    pVtab->zErrMsg = 0;
+  }
+}
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+
+#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
+
+/*
+** If the second argument is not NULL, release any allocations associated 
+** with the memory cells in the p->aMem[] array. Also free the UnpackedRecord
+** structure itself, using sqlite3DbFree().
+**
+** This function is used to free UnpackedRecord structures allocated by
+** the vdbeUnpackRecord() function found in vdbeapi.c.
+*/
+static void vdbeFreeUnpacked(sqlite3 *db, int nField, UnpackedRecord *p){
+  if( p ){
+    int i;
+    for(i=0; i<nField; i++){
+      Mem *pMem = &p->aMem[i];
+      if( pMem->zMalloc ) sqlite3VdbeMemRelease(pMem);
+    }
+    sqlite3DbFree(db, p);
+  }
+}
+#endif /* SQLITE_ENABLE_PREUPDATE_HOOK */
+
+#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
+/*
+** Invoke the pre-update hook. If this is an UPDATE or DELETE pre-update call,
+** then cursor passed as the second argument should point to the row about
+** to be update or deleted. If the application calls sqlite3_preupdate_old(),
+** the required value will be read from the row the cursor points to.
+*/
+void sqlite3VdbePreUpdateHook(
+  Vdbe *v,                        /* Vdbe pre-update hook is invoked by */
+  VdbeCursor *pCsr,               /* Cursor to grab old.* values from */
+  int op,                         /* SQLITE_INSERT, UPDATE or DELETE */
+  const char *zDb,                /* Database name */
+  Table *pTab,                    /* Modified table */
+  i64 iKey1,                      /* Initial key value */
+  int iReg                        /* Register for new.* record */
+){
+  sqlite3 *db = v->db;
+  i64 iKey2;
+  PreUpdate preupdate;
+  const char *zTbl = pTab->zName;
+  static const u8 fakeSortOrder = 0;
+
+  assert( db->pPreUpdate==0 );
+  memset(&preupdate, 0, sizeof(PreUpdate));
+  if( HasRowid(pTab)==0 ){
+    iKey1 = iKey2 = 0;
+    preupdate.pPk = sqlite3PrimaryKeyIndex(pTab);
+  }else{
+    if( op==SQLITE_UPDATE ){
+      iKey2 = v->aMem[iReg].u.i;
+    }else{
+      iKey2 = iKey1;
+    }
+  }
+
+  assert( pCsr->nField==pTab->nCol 
+       || (pCsr->nField==pTab->nCol+1 && op==SQLITE_DELETE && iReg==-1)
+  );
+
+  preupdate.v = v;
+  preupdate.pCsr = pCsr;
+  preupdate.op = op;
+  preupdate.iNewReg = iReg;
+  preupdate.keyinfo.db = db;
+  preupdate.keyinfo.enc = ENC(db);
+  preupdate.keyinfo.nField = pTab->nCol;
+  preupdate.keyinfo.aSortOrder = (u8*)&fakeSortOrder;
+  preupdate.iKey1 = iKey1;
+  preupdate.iKey2 = iKey2;
+  preupdate.pTab = pTab;
+
+  db->pPreUpdate = &preupdate;
+  db->xPreUpdateCallback(db->pPreUpdateArg, db, op, zDb, zTbl, iKey1, iKey2);
+  db->pPreUpdate = 0;
+  sqlite3DbFree(db, preupdate.aRecord);
+  vdbeFreeUnpacked(db, preupdate.keyinfo.nField+1, preupdate.pUnpacked);
+  vdbeFreeUnpacked(db, preupdate.keyinfo.nField+1, preupdate.pNewUnpacked);
+  if( preupdate.aNew ){
+    int i;
+    for(i=0; i<pCsr->nField; i++){
+      sqlite3VdbeMemRelease(&preupdate.aNew[i]);
+    }
+    sqlite3DbFree(db, preupdate.aNew);
+  }
+}
+#endif /* SQLITE_ENABLE_PREUPDATE_HOOK */