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third_party/sqlite/src/src/analyze.c

Index: third_party/sqlite/src/src/analyze.c
diff --git a/third_party/sqlite/src/src/analyze.c b/third_party/sqlite/src/src/analyze.c
new file mode 100644
index 0000000000000000000000000000000000000000..2444e7492329e0a33f171f5681b9b22a206f9e71
--- /dev/null
+++ b/third_party/sqlite/src/src/analyze.c
@@ -0,0 +1,719 @@
+/*
+** 2005 July 8
+**
+** 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 associated with the ANALYZE command.
+*/
+#ifndef SQLITE_OMIT_ANALYZE
+#include "sqliteInt.h"
+
+/*
+** This routine generates code that opens the sqlite_stat1 table for
+** writing with cursor iStatCur. If the library was built with the
+** SQLITE_ENABLE_STAT2 macro defined, then the sqlite_stat2 table is
+** opened for writing using cursor (iStatCur+1)
+**
+** If the sqlite_stat1 tables does not previously exist, it is created.
+** Similarly, if the sqlite_stat2 table does not exist and the library
+** is compiled with SQLITE_ENABLE_STAT2 defined, it is created. 
+**
+** Argument zWhere may be a pointer to a buffer containing a table name,
+** or it may be a NULL pointer. If it is not NULL, then all entries in
+** the sqlite_stat1 and (if applicable) sqlite_stat2 tables associated
+** with the named table are deleted. If zWhere==0, then code is generated
+** to delete all stat table entries.
+*/
+static void openStatTable(
+  Parse *pParse,          /* Parsing context */
+  int iDb,                /* The database we are looking in */
+  int iStatCur,           /* Open the sqlite_stat1 table on this cursor */
+  const char *zWhere,     /* Delete entries for this table or index */
+  const char *zWhereType  /* Either "tbl" or "idx" */
+){
+  static const struct {
+    const char *zName;
+    const char *zCols;
+  } aTable[] = {
+    { "sqlite_stat1", "tbl,idx,stat" },
+#ifdef SQLITE_ENABLE_STAT2
+    { "sqlite_stat2", "tbl,idx,sampleno,sample" },
+#endif
+  };
+
+  int aRoot[] = {0, 0};
+  u8 aCreateTbl[] = {0, 0};
+
+  int i;
+  sqlite3 *db = pParse->db;
+  Db *pDb;
+  Vdbe *v = sqlite3GetVdbe(pParse);
+  if( v==0 ) return;
+  assert( sqlite3BtreeHoldsAllMutexes(db) );
+  assert( sqlite3VdbeDb(v)==db );
+  pDb = &db->aDb[iDb];
+
+  for(i=0; i<ArraySize(aTable); i++){
+    const char *zTab = aTable[i].zName;
+    Table *pStat;
+    if( (pStat = sqlite3FindTable(db, zTab, pDb->zName))==0 ){
+      /* The sqlite_stat[12] table does not exist. Create it. Note that a 
+      ** side-effect of the CREATE TABLE statement is to leave the rootpage 
+      ** of the new table in register pParse->regRoot. This is important 
+      ** because the OpenWrite opcode below will be needing it. */
+      sqlite3NestedParse(pParse,
+          "CREATE TABLE %Q.%s(%s)", pDb->zName, zTab, aTable[i].zCols
+      );
+      aRoot[i] = pParse->regRoot;
+      aCreateTbl[i] = 1;
+    }else{
+      /* The table already exists. If zWhere is not NULL, delete all entries 
+      ** associated with the table zWhere. If zWhere is NULL, delete the
+      ** entire contents of the table. */
+      aRoot[i] = pStat->tnum;
+      sqlite3TableLock(pParse, iDb, aRoot[i], 1, zTab);
+      if( zWhere ){
+        sqlite3NestedParse(pParse,
+           "DELETE FROM %Q.%s WHERE %s=%Q", pDb->zName, zTab, zWhereType, zWhere
+        );
+      }else{
+        /* The sqlite_stat[12] table already exists.  Delete all rows. */
+        sqlite3VdbeAddOp2(v, OP_Clear, aRoot[i], iDb);
+      }
+    }
+  }
+
+  /* Open the sqlite_stat[12] tables for writing. */
+  for(i=0; i<ArraySize(aTable); i++){
+    sqlite3VdbeAddOp3(v, OP_OpenWrite, iStatCur+i, aRoot[i], iDb);
+    sqlite3VdbeChangeP4(v, -1, (char *)3, P4_INT32);
+    sqlite3VdbeChangeP5(v, aCreateTbl[i]);
+  }
+}
+
+/*
+** Generate code to do an analysis of all indices associated with
+** a single table.
+*/
+static void analyzeOneTable(
+  Parse *pParse,   /* Parser context */
+  Table *pTab,     /* Table whose indices are to be analyzed */
+  Index *pOnlyIdx, /* If not NULL, only analyze this one index */
+  int iStatCur,    /* Index of VdbeCursor that writes the sqlite_stat1 table */
+  int iMem         /* Available memory locations begin here */
+){
+  sqlite3 *db = pParse->db;    /* Database handle */
+  Index *pIdx;                 /* An index to being analyzed */
+  int iIdxCur;                 /* Cursor open on index being analyzed */
+  Vdbe *v;                     /* The virtual machine being built up */
+  int i;                       /* Loop counter */
+  int topOfLoop;               /* The top of the loop */
+  int endOfLoop;               /* The end of the loop */
+  int jZeroRows = -1;          /* Jump from here if number of rows is zero */
+  int iDb;                     /* Index of database containing pTab */
+  int regTabname = iMem++;     /* Register containing table name */
+  int regIdxname = iMem++;     /* Register containing index name */
+  int regSampleno = iMem++;    /* Register containing next sample number */
+  int regCol = iMem++;         /* Content of a column analyzed table */
+  int regRec = iMem++;         /* Register holding completed record */
+  int regTemp = iMem++;        /* Temporary use register */
+  int regRowid = iMem++;       /* Rowid for the inserted record */
+
+#ifdef SQLITE_ENABLE_STAT2
+  int addr = 0;                /* Instruction address */
+  int regTemp2 = iMem++;       /* Temporary use register */
+  int regSamplerecno = iMem++; /* Index of next sample to record */
+  int regRecno = iMem++;       /* Current sample index */
+  int regLast = iMem++;        /* Index of last sample to record */
+  int regFirst = iMem++;       /* Index of first sample to record */
+#endif
+
+  v = sqlite3GetVdbe(pParse);
+  if( v==0 || NEVER(pTab==0) ){
+    return;
+  }
+  if( pTab->tnum==0 ){
+    /* Do not gather statistics on views or virtual tables */
+    return;
+  }
+  if( sqlite3_strnicmp(pTab->zName, "sqlite_", 7)==0 ){
+    /* Do not gather statistics on system tables */
+    return;
+  }
+  assert( sqlite3BtreeHoldsAllMutexes(db) );
+  iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
+  assert( iDb>=0 );
+  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
+#ifndef SQLITE_OMIT_AUTHORIZATION
+  if( sqlite3AuthCheck(pParse, SQLITE_ANALYZE, pTab->zName, 0,
+      db->aDb[iDb].zName ) ){
+    return;
+  }
+#endif
+
+  /* Establish a read-lock on the table at the shared-cache level. */
+  sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
+
+  iIdxCur = pParse->nTab++;
+  sqlite3VdbeAddOp4(v, OP_String8, 0, regTabname, 0, pTab->zName, 0);
+  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+    int nCol;
+    KeyInfo *pKey;
+
+    if( pOnlyIdx && pOnlyIdx!=pIdx ) continue;
+    nCol = pIdx->nColumn;
+    pKey = sqlite3IndexKeyinfo(pParse, pIdx);
+    if( iMem+1+(nCol*2)>pParse->nMem ){
+      pParse->nMem = iMem+1+(nCol*2);
+    }
+
+    /* Open a cursor to the index to be analyzed. */
+    assert( iDb==sqlite3SchemaToIndex(db, pIdx->pSchema) );
+    sqlite3VdbeAddOp4(v, OP_OpenRead, iIdxCur, pIdx->tnum, iDb,
+        (char *)pKey, P4_KEYINFO_HANDOFF);
+    VdbeComment((v, "%s", pIdx->zName));
+
+    /* Populate the register containing the index name. */
+    sqlite3VdbeAddOp4(v, OP_String8, 0, regIdxname, 0, pIdx->zName, 0);
+
+#ifdef SQLITE_ENABLE_STAT2
+
+    /* If this iteration of the loop is generating code to analyze the
+    ** first index in the pTab->pIndex list, then register regLast has
+    ** not been populated. In this case populate it now.  */
+    if( pTab->pIndex==pIdx ){
+      sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_INDEX_SAMPLES, regSamplerecno);
+      sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_INDEX_SAMPLES*2-1, regTemp);
+      sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_INDEX_SAMPLES*2, regTemp2);
+
+      sqlite3VdbeAddOp2(v, OP_Count, iIdxCur, regLast);
+      sqlite3VdbeAddOp2(v, OP_Null, 0, regFirst);
+      addr = sqlite3VdbeAddOp3(v, OP_Lt, regSamplerecno, 0, regLast);
+      sqlite3VdbeAddOp3(v, OP_Divide, regTemp2, regLast, regFirst);
+      sqlite3VdbeAddOp3(v, OP_Multiply, regLast, regTemp, regLast);
+      sqlite3VdbeAddOp2(v, OP_AddImm, regLast, SQLITE_INDEX_SAMPLES*2-2);
+      sqlite3VdbeAddOp3(v, OP_Divide,  regTemp2, regLast, regLast);
+      sqlite3VdbeJumpHere(v, addr);
+    }
+
+    /* Zero the regSampleno and regRecno registers. */
+    sqlite3VdbeAddOp2(v, OP_Integer, 0, regSampleno);
+    sqlite3VdbeAddOp2(v, OP_Integer, 0, regRecno);
+    sqlite3VdbeAddOp2(v, OP_Copy, regFirst, regSamplerecno);
+#endif
+
+    /* The block of memory cells initialized here is used as follows.
+    **
+    **    iMem:                
+    **        The total number of rows in the table.
+    **
+    **    iMem+1 .. iMem+nCol: 
+    **        Number of distinct entries in index considering the 
+    **        left-most N columns only, where N is between 1 and nCol, 
+    **        inclusive.
+    **
+    **    iMem+nCol+1 .. Mem+2*nCol:  
+    **        Previous value of indexed columns, from left to right.
+    **
+    ** Cells iMem through iMem+nCol are initialized to 0. The others are 
+    ** initialized to contain an SQL NULL.
+    */
+    for(i=0; i<=nCol; i++){
+      sqlite3VdbeAddOp2(v, OP_Integer, 0, iMem+i);
+    }
+    for(i=0; i<nCol; i++){
+      sqlite3VdbeAddOp2(v, OP_Null, 0, iMem+nCol+i+1);
+    }
+
+    /* Start the analysis loop. This loop runs through all the entries in
+    ** the index b-tree.  */
+    endOfLoop = sqlite3VdbeMakeLabel(v);
+    sqlite3VdbeAddOp2(v, OP_Rewind, iIdxCur, endOfLoop);
+    topOfLoop = sqlite3VdbeCurrentAddr(v);
+    sqlite3VdbeAddOp2(v, OP_AddImm, iMem, 1);
+
+    for(i=0; i<nCol; i++){
+      CollSeq *pColl;
+      sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, regCol);
+      if( i==0 ){
+#ifdef SQLITE_ENABLE_STAT2
+        /* Check if the record that cursor iIdxCur points to contains a
+        ** value that should be stored in the sqlite_stat2 table. If so,
+        ** store it.  */
+        int ne = sqlite3VdbeAddOp3(v, OP_Ne, regRecno, 0, regSamplerecno);
+        assert( regTabname+1==regIdxname 
+             && regTabname+2==regSampleno
+             && regTabname+3==regCol
+        );
+        sqlite3VdbeChangeP5(v, SQLITE_JUMPIFNULL);
+        sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 4, regRec, "aaab", 0);
+        sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur+1, regRowid);
+        sqlite3VdbeAddOp3(v, OP_Insert, iStatCur+1, regRec, regRowid);
+
+        /* Calculate new values for regSamplerecno and regSampleno.
+        **
+        **   sampleno = sampleno + 1
+        **   samplerecno = samplerecno+(remaining records)/(remaining samples)
+        */
+        sqlite3VdbeAddOp2(v, OP_AddImm, regSampleno, 1);
+        sqlite3VdbeAddOp3(v, OP_Subtract, regRecno, regLast, regTemp);
+        sqlite3VdbeAddOp2(v, OP_AddImm, regTemp, -1);
+        sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_INDEX_SAMPLES, regTemp2);
+        sqlite3VdbeAddOp3(v, OP_Subtract, regSampleno, regTemp2, regTemp2);
+        sqlite3VdbeAddOp3(v, OP_Divide, regTemp2, regTemp, regTemp);
+        sqlite3VdbeAddOp3(v, OP_Add, regSamplerecno, regTemp, regSamplerecno);
+
+        sqlite3VdbeJumpHere(v, ne);
+        sqlite3VdbeAddOp2(v, OP_AddImm, regRecno, 1);
+#endif
+
+        /* Always record the very first row */
+        sqlite3VdbeAddOp1(v, OP_IfNot, iMem+1);
+      }
+      assert( pIdx->azColl!=0 );
+      assert( pIdx->azColl[i]!=0 );
+      pColl = sqlite3LocateCollSeq(pParse, pIdx->azColl[i]);
+      sqlite3VdbeAddOp4(v, OP_Ne, regCol, 0, iMem+nCol+i+1,
+                       (char*)pColl, P4_COLLSEQ);
+      sqlite3VdbeChangeP5(v, SQLITE_NULLEQ);
+    }
+    if( db->mallocFailed ){
+      /* If a malloc failure has occurred, then the result of the expression 
+      ** passed as the second argument to the call to sqlite3VdbeJumpHere() 
+      ** below may be negative. Which causes an assert() to fail (or an
+      ** out-of-bounds write if SQLITE_DEBUG is not defined).  */
+      return;
+    }
+    sqlite3VdbeAddOp2(v, OP_Goto, 0, endOfLoop);
+    for(i=0; i<nCol; i++){
+      int addr2 = sqlite3VdbeCurrentAddr(v) - (nCol*2);
+      if( i==0 ){
+        sqlite3VdbeJumpHere(v, addr2-1);  /* Set jump dest for the OP_IfNot */
+      }
+      sqlite3VdbeJumpHere(v, addr2);      /* Set jump dest for the OP_Ne */
+      sqlite3VdbeAddOp2(v, OP_AddImm, iMem+i+1, 1);
+      sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, iMem+nCol+i+1);
+    }
+
+    /* End of the analysis loop. */
+    sqlite3VdbeResolveLabel(v, endOfLoop);
+    sqlite3VdbeAddOp2(v, OP_Next, iIdxCur, topOfLoop);
+    sqlite3VdbeAddOp1(v, OP_Close, iIdxCur);
+
+    /* Store the results in sqlite_stat1.
+    **
+    ** The result is a single row of the sqlite_stat1 table.  The first
+    ** two columns are the names of the table and index.  The third column
+    ** is a string composed of a list of integer statistics about the
+    ** index.  The first integer in the list is the total number of entries
+    ** in the index.  There is one additional integer in the list for each
+    ** column of the table.  This additional integer is a guess of how many
+    ** rows of the table the index will select.  If D is the count of distinct
+    ** values and K is the total number of rows, then the integer is computed
+    ** as:
+    **
+    **        I = (K+D-1)/D
+    **
+    ** If K==0 then no entry is made into the sqlite_stat1 table.  
+    ** If K>0 then it is always the case the D>0 so division by zero
+    ** is never possible.
+    */
+    sqlite3VdbeAddOp2(v, OP_SCopy, iMem, regSampleno);
+    if( jZeroRows<0 ){
+      jZeroRows = sqlite3VdbeAddOp1(v, OP_IfNot, iMem);
+    }
+    for(i=0; i<nCol; i++){
+      sqlite3VdbeAddOp4(v, OP_String8, 0, regTemp, 0, " ", 0);
+      sqlite3VdbeAddOp3(v, OP_Concat, regTemp, regSampleno, regSampleno);
+      sqlite3VdbeAddOp3(v, OP_Add, iMem, iMem+i+1, regTemp);
+      sqlite3VdbeAddOp2(v, OP_AddImm, regTemp, -1);
+      sqlite3VdbeAddOp3(v, OP_Divide, iMem+i+1, regTemp, regTemp);
+      sqlite3VdbeAddOp1(v, OP_ToInt, regTemp);
+      sqlite3VdbeAddOp3(v, OP_Concat, regTemp, regSampleno, regSampleno);
+    }
+    sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 3, regRec, "aaa", 0);
+    sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur, regRowid);
+    sqlite3VdbeAddOp3(v, OP_Insert, iStatCur, regRec, regRowid);
+    sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
+  }
+
+  /* If the table has no indices, create a single sqlite_stat1 entry
+  ** containing NULL as the index name and the row count as the content.
+  */
+  if( pTab->pIndex==0 ){
+    sqlite3VdbeAddOp3(v, OP_OpenRead, iIdxCur, pTab->tnum, iDb);
+    VdbeComment((v, "%s", pTab->zName));
+    sqlite3VdbeAddOp2(v, OP_Count, iIdxCur, regSampleno);
+    sqlite3VdbeAddOp1(v, OP_Close, iIdxCur);
+    jZeroRows = sqlite3VdbeAddOp1(v, OP_IfNot, regSampleno);
+  }else{
+    sqlite3VdbeJumpHere(v, jZeroRows);
+    jZeroRows = sqlite3VdbeAddOp0(v, OP_Goto);
+  }
+  sqlite3VdbeAddOp2(v, OP_Null, 0, regIdxname);
+  sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 3, regRec, "aaa", 0);
+  sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur, regRowid);
+  sqlite3VdbeAddOp3(v, OP_Insert, iStatCur, regRec, regRowid);
+  sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
+  if( pParse->nMem<regRec ) pParse->nMem = regRec;
+  sqlite3VdbeJumpHere(v, jZeroRows);
+}
+
+/*
+** Generate code that will cause the most recent index analysis to
+** be loaded into internal hash tables where is can be used.
+*/
+static void loadAnalysis(Parse *pParse, int iDb){
+  Vdbe *v = sqlite3GetVdbe(pParse);
+  if( v ){
+    sqlite3VdbeAddOp1(v, OP_LoadAnalysis, iDb);
+  }
+}
+
+/*
+** Generate code that will do an analysis of an entire database
+*/
+static void analyzeDatabase(Parse *pParse, int iDb){
+  sqlite3 *db = pParse->db;
+  Schema *pSchema = db->aDb[iDb].pSchema;    /* Schema of database iDb */
+  HashElem *k;
+  int iStatCur;
+  int iMem;
+
+  sqlite3BeginWriteOperation(pParse, 0, iDb);
+  iStatCur = pParse->nTab;
+  pParse->nTab += 2;
+  openStatTable(pParse, iDb, iStatCur, 0, 0);
+  iMem = pParse->nMem+1;
+  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
+  for(k=sqliteHashFirst(&pSchema->tblHash); k; k=sqliteHashNext(k)){
+    Table *pTab = (Table*)sqliteHashData(k);
+    analyzeOneTable(pParse, pTab, 0, iStatCur, iMem);
+  }
+  loadAnalysis(pParse, iDb);
+}
+
+/*
+** Generate code that will do an analysis of a single table in
+** a database.  If pOnlyIdx is not NULL then it is a single index
+** in pTab that should be analyzed.
+*/
+static void analyzeTable(Parse *pParse, Table *pTab, Index *pOnlyIdx){
+  int iDb;
+  int iStatCur;
+
+  assert( pTab!=0 );
+  assert( sqlite3BtreeHoldsAllMutexes(pParse->db) );
+  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
+  sqlite3BeginWriteOperation(pParse, 0, iDb);
+  iStatCur = pParse->nTab;
+  pParse->nTab += 2;
+  if( pOnlyIdx ){
+    openStatTable(pParse, iDb, iStatCur, pOnlyIdx->zName, "idx");
+  }else{
+    openStatTable(pParse, iDb, iStatCur, pTab->zName, "tbl");
+  }
+  analyzeOneTable(pParse, pTab, pOnlyIdx, iStatCur, pParse->nMem+1);
+  loadAnalysis(pParse, iDb);
+}
+
+/*
+** Generate code for the ANALYZE command.  The parser calls this routine
+** when it recognizes an ANALYZE command.
+**
+**        ANALYZE                            -- 1
+**        ANALYZE  <database>                -- 2
+**        ANALYZE  ?<database>.?<tablename>  -- 3
+**
+** Form 1 causes all indices in all attached databases to be analyzed.
+** Form 2 analyzes all indices the single database named.
+** Form 3 analyzes all indices associated with the named table.
+*/
+void sqlite3Analyze(Parse *pParse, Token *pName1, Token *pName2){
+  sqlite3 *db = pParse->db;
+  int iDb;
+  int i;
+  char *z, *zDb;
+  Table *pTab;
+  Index *pIdx;
+  Token *pTableName;
+
+  /* Read the database schema. If an error occurs, leave an error message
+  ** and code in pParse and return NULL. */
+  assert( sqlite3BtreeHoldsAllMutexes(pParse->db) );
+  if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){
+    return;
+  }
+
+  assert( pName2!=0 || pName1==0 );
+  if( pName1==0 ){
+    /* Form 1:  Analyze everything */
+    for(i=0; i<db->nDb; i++){
+      if( i==1 ) continue;  /* Do not analyze the TEMP database */
+      analyzeDatabase(pParse, i);
+    }
+  }else if( pName2->n==0 ){
+    /* Form 2:  Analyze the database or table named */
+    iDb = sqlite3FindDb(db, pName1);
+    if( iDb>=0 ){
+      analyzeDatabase(pParse, iDb);
+    }else{
+      z = sqlite3NameFromToken(db, pName1);
+      if( z ){
+        if( (pIdx = sqlite3FindIndex(db, z, 0))!=0 ){
+          analyzeTable(pParse, pIdx->pTable, pIdx);
+        }else if( (pTab = sqlite3LocateTable(pParse, 0, z, 0))!=0 ){
+          analyzeTable(pParse, pTab, 0);
+        }
+        sqlite3DbFree(db, z);
+      }
+    }
+  }else{
+    /* Form 3: Analyze the fully qualified table name */
+    iDb = sqlite3TwoPartName(pParse, pName1, pName2, &pTableName);
+    if( iDb>=0 ){
+      zDb = db->aDb[iDb].zName;
+      z = sqlite3NameFromToken(db, pTableName);
+      if( z ){
+        if( (pIdx = sqlite3FindIndex(db, z, zDb))!=0 ){
+          analyzeTable(pParse, pIdx->pTable, pIdx);
+        }else if( (pTab = sqlite3LocateTable(pParse, 0, z, zDb))!=0 ){
+          analyzeTable(pParse, pTab, 0);
+        }
+        sqlite3DbFree(db, z);
+      }
+    }   
+  }
+}
+
+/*
+** Used to pass information from the analyzer reader through to the
+** callback routine.
+*/
+typedef struct analysisInfo analysisInfo;
+struct analysisInfo {
+  sqlite3 *db;
+  const char *zDatabase;
+};
+
+/*
+** This callback is invoked once for each index when reading the
+** sqlite_stat1 table.  
+**
+**     argv[0] = name of the table
+**     argv[1] = name of the index (might be NULL)
+**     argv[2] = results of analysis - on integer for each column
+**
+** Entries for which argv[1]==NULL simply record the number of rows in
+** the table.
+*/
+static int analysisLoader(void *pData, int argc, char **argv, char **NotUsed){
+  analysisInfo *pInfo = (analysisInfo*)pData;
+  Index *pIndex;
+  Table *pTable;
+  int i, c, n;
+  unsigned int v;
+  const char *z;
+
+  assert( argc==3 );
+  UNUSED_PARAMETER2(NotUsed, argc);
+
+  if( argv==0 || argv[0]==0 || argv[2]==0 ){
+    return 0;
+  }
+  pTable = sqlite3FindTable(pInfo->db, argv[0], pInfo->zDatabase);
+  if( pTable==0 ){
+    return 0;
+  }
+  if( argv[1] ){
+    pIndex = sqlite3FindIndex(pInfo->db, argv[1], pInfo->zDatabase);
+  }else{
+    pIndex = 0;
+  }
+  n = pIndex ? pIndex->nColumn : 0;
+  z = argv[2];
+  for(i=0; *z && i<=n; i++){
+    v = 0;
+    while( (c=z[0])>='0' && c<='9' ){
+      v = v*10 + c - '0';
+      z++;
+    }
+    if( i==0 ) pTable->nRowEst = v;
+    if( pIndex==0 ) break;
+    pIndex->aiRowEst[i] = v;
+    if( *z==' ' ) z++;
+    if( strcmp(z, "unordered")==0 ){
+      pIndex->bUnordered = 1;
+      break;
+    }
+  }
+  return 0;
+}
+
+/*
+** If the Index.aSample variable is not NULL, delete the aSample[] array
+** and its contents.
+*/
+void sqlite3DeleteIndexSamples(sqlite3 *db, Index *pIdx){
+#ifdef SQLITE_ENABLE_STAT2
+  if( pIdx->aSample ){
+    int j;
+    for(j=0; j<SQLITE_INDEX_SAMPLES; j++){
+      IndexSample *p = &pIdx->aSample[j];
+      if( p->eType==SQLITE_TEXT || p->eType==SQLITE_BLOB ){
+        sqlite3DbFree(db, p->u.z);
+      }
+    }
+    sqlite3DbFree(db, pIdx->aSample);
+  }
+#else
+  UNUSED_PARAMETER(db);
+  UNUSED_PARAMETER(pIdx);
+#endif
+}
+
+/*
+** Load the content of the sqlite_stat1 and sqlite_stat2 tables. The
+** contents of sqlite_stat1 are used to populate the Index.aiRowEst[]
+** arrays. The contents of sqlite_stat2 are used to populate the
+** Index.aSample[] arrays.
+**
+** If the sqlite_stat1 table is not present in the database, SQLITE_ERROR
+** is returned. In this case, even if SQLITE_ENABLE_STAT2 was defined 
+** during compilation and the sqlite_stat2 table is present, no data is 
+** read from it.
+**
+** If SQLITE_ENABLE_STAT2 was defined during compilation and the 
+** sqlite_stat2 table is not present in the database, SQLITE_ERROR is
+** returned. However, in this case, data is read from the sqlite_stat1
+** table (if it is present) before returning.
+**
+** If an OOM error occurs, this function always sets db->mallocFailed.
+** This means if the caller does not care about other errors, the return
+** code may be ignored.
+*/
+int sqlite3AnalysisLoad(sqlite3 *db, int iDb){
+  analysisInfo sInfo;
+  HashElem *i;
+  char *zSql;
+  int rc;
+
+  assert( iDb>=0 && iDb<db->nDb );
+  assert( db->aDb[iDb].pBt!=0 );
+
+  /* Clear any prior statistics */
+  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
+  for(i=sqliteHashFirst(&db->aDb[iDb].pSchema->idxHash);i;i=sqliteHashNext(i)){
+    Index *pIdx = sqliteHashData(i);
+    sqlite3DefaultRowEst(pIdx);
+    sqlite3DeleteIndexSamples(db, pIdx);
+    pIdx->aSample = 0;
+  }
+
+  /* Check to make sure the sqlite_stat1 table exists */
+  sInfo.db = db;
+  sInfo.zDatabase = db->aDb[iDb].zName;
+  if( sqlite3FindTable(db, "sqlite_stat1", sInfo.zDatabase)==0 ){
+    return SQLITE_ERROR;
+  }
+
+  /* Load new statistics out of the sqlite_stat1 table */
+  zSql = sqlite3MPrintf(db, 
+      "SELECT tbl, idx, stat FROM %Q.sqlite_stat1", sInfo.zDatabase);
+  if( zSql==0 ){
+    rc = SQLITE_NOMEM;
+  }else{
+    rc = sqlite3_exec(db, zSql, analysisLoader, &sInfo, 0);
+    sqlite3DbFree(db, zSql);
+  }
+
+
+  /* Load the statistics from the sqlite_stat2 table. */
+#ifdef SQLITE_ENABLE_STAT2
+  if( rc==SQLITE_OK && !sqlite3FindTable(db, "sqlite_stat2", sInfo.zDatabase) ){
+    rc = SQLITE_ERROR;
+  }
+  if( rc==SQLITE_OK ){
+    sqlite3_stmt *pStmt = 0;
+
+    zSql = sqlite3MPrintf(db, 
+        "SELECT idx,sampleno,sample FROM %Q.sqlite_stat2", sInfo.zDatabase);
+    if( !zSql ){
+      rc = SQLITE_NOMEM;
+    }else{
+      rc = sqlite3_prepare(db, zSql, -1, &pStmt, 0);
+      sqlite3DbFree(db, zSql);
+    }
+
+    if( rc==SQLITE_OK ){
+      while( sqlite3_step(pStmt)==SQLITE_ROW ){
+        char *zIndex;   /* Index name */
+        Index *pIdx;    /* Pointer to the index object */
+
+        zIndex = (char *)sqlite3_column_text(pStmt, 0);
+        pIdx = zIndex ? sqlite3FindIndex(db, zIndex, sInfo.zDatabase) : 0;
+        if( pIdx ){
+          int iSample = sqlite3_column_int(pStmt, 1);
+          if( iSample<SQLITE_INDEX_SAMPLES && iSample>=0 ){
+            int eType = sqlite3_column_type(pStmt, 2);
+
+            if( pIdx->aSample==0 ){
+              static const int sz = sizeof(IndexSample)*SQLITE_INDEX_SAMPLES;
+              pIdx->aSample = (IndexSample *)sqlite3DbMallocRaw(0, sz);
+              if( pIdx->aSample==0 ){
+                db->mallocFailed = 1;
+                break;
+              }
+	      memset(pIdx->aSample, 0, sz);
+            }
+
+            assert( pIdx->aSample );
+            {
+              IndexSample *pSample = &pIdx->aSample[iSample];
+              pSample->eType = (u8)eType;
+              if( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT ){
+                pSample->u.r = sqlite3_column_double(pStmt, 2);
+              }else if( eType==SQLITE_TEXT || eType==SQLITE_BLOB ){
+                const char *z = (const char *)(
+                    (eType==SQLITE_BLOB) ?
+                    sqlite3_column_blob(pStmt, 2):
+                    sqlite3_column_text(pStmt, 2)
+                );
+                int n = sqlite3_column_bytes(pStmt, 2);
+                if( n>24 ){
+                  n = 24;
+                }
+                pSample->nByte = (u8)n;
+                if( n < 1){
+                  pSample->u.z = 0;
+                }else{
+                  pSample->u.z = sqlite3DbStrNDup(0, z, n);
+                  if( pSample->u.z==0 ){
+                    db->mallocFailed = 1;
+                    break;
+                  }
+                }
+              }
+            }
+          }
+        }
+      }
+      rc = sqlite3_finalize(pStmt);
+    }
+  }
+#endif
+
+  if( rc==SQLITE_NOMEM ){
+    db->mallocFailed = 1;
+  }
+  return rc;
+}
+
+
+#endif /* SQLITE_OMIT_ANALYZE */