[sql] Import reference version of SQLite 3.17..

third_party/sqlite/sqlite-src-3170000/src/test8.c

+/*
+** 2006 June 10
+**
+** 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.
+**
+*************************************************************************
+** Code for testing the virtual table interfaces.  This code
+** is not included in the SQLite library.  It is used for automated
+** testing of the SQLite library.
+*/
+#include "sqliteInt.h"
+#if defined(INCLUDE_SQLITE_TCL_H)
+#  include "sqlite_tcl.h"
+#else
+#  include "tcl.h"
+#endif
+#include <stdlib.h>
+#include <string.h>
+
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+
+typedef struct echo_vtab echo_vtab;
+typedef struct echo_cursor echo_cursor;
+
+/*
+** The test module defined in this file uses four global Tcl variables to
+** commicate with test-scripts:
+**
+**     $::echo_module
+**     $::echo_module_sync_fail
+**     $::echo_module_begin_fail
+**     $::echo_module_cost
+**
+** The variable ::echo_module is a list. Each time one of the following
+** methods is called, one or more elements are appended to the list.
+** This is used for automated testing of virtual table modules.
+**
+** The ::echo_module_sync_fail variable is set by test scripts and read
+** by code in this file. If it is set to the name of a real table in the
+** the database, then all xSync operations on echo virtual tables that
+** use the named table as a backing store will fail.
+*/
+
+/*
+** Errors can be provoked within the following echo virtual table methods:
+**
+**   xBestIndex   xOpen     xFilter   xNext   
+**   xColumn      xRowid    xUpdate   xSync   
+**   xBegin       xRename
+**
+** This is done by setting the global tcl variable:
+**
+**   echo_module_fail($method,$tbl)
+**
+** where $method is set to the name of the virtual table method to fail
+** (i.e. "xBestIndex") and $tbl is the name of the table being echoed (not
+** the name of the virtual table, the name of the underlying real table).
+*/
+
+/* 
+** An echo virtual-table object.
+**
+** echo.vtab.aIndex is an array of booleans. The nth entry is true if 
+** the nth column of the real table is the left-most column of an index
+** (implicit or otherwise). In other words, if SQLite can optimize
+** a query like "SELECT * FROM real_table WHERE col = ?".
+**
+** Member variable aCol[] contains copies of the column names of the real
+** table.
+*/
+struct echo_vtab {
+  sqlite3_vtab base;
+  Tcl_Interp *interp;     /* Tcl interpreter containing debug variables */
+  sqlite3 *db;            /* Database connection */
+
+  int isPattern;
+  int inTransaction;      /* True if within a transaction */
+  char *zThis;            /* Name of the echo table */
+  char *zTableName;       /* Name of the real table */
+  char *zLogName;         /* Name of the log table */
+  int nCol;               /* Number of columns in the real table */
+  int *aIndex;            /* Array of size nCol. True if column has an index */
+  char **aCol;            /* Array of size nCol. Column names */
+};
+
+/* An echo cursor object */
+struct echo_cursor {
+  sqlite3_vtab_cursor base;
+  sqlite3_stmt *pStmt;
+};
+
+static int simulateVtabError(echo_vtab *p, const char *zMethod){
+  const char *zErr;
+  char zVarname[128];
+  zVarname[127] = '\0';
+  sqlite3_snprintf(127, zVarname, "echo_module_fail(%s,%s)", zMethod, p->zTableName);
+  zErr = Tcl_GetVar(p->interp, zVarname, TCL_GLOBAL_ONLY);
+  if( zErr ){
+    p->base.zErrMsg = sqlite3_mprintf("echo-vtab-error: %s", zErr);
+  }
+  return (zErr!=0);
+}
+
+/*
+** Convert an SQL-style quoted string into a normal string by removing
+** the quote characters.  The conversion is done in-place.  If the
+** input does not begin with a quote character, then this routine
+** is a no-op.
+**
+** Examples:
+**
+**     "abc"   becomes   abc
+**     'xyz'   becomes   xyz
+**     [pqr]   becomes   pqr
+**     `mno`   becomes   mno
+*/
+static void dequoteString(char *z){
+  int quote;
+  int i, j;
+  if( z==0 ) return;
+  quote = z[0];
+  switch( quote ){
+    case '\'':  break;
+    case '"':   break;
+    case '`':   break;                /* For MySQL compatibility */
+    case '[':   quote = ']';  break;  /* For MS SqlServer compatibility */
+    default:    return;
+  }
+  for(i=1, j=0; z[i]; i++){
+    if( z[i]==quote ){
+      if( z[i+1]==quote ){
+        z[j++] = quote;
+        i++;
+      }else{
+        z[j++] = 0;
+        break;
+      }
+    }else{
+      z[j++] = z[i];
+    }
+  }
+}
+
+/*
+** Retrieve the column names for the table named zTab via database
+** connection db. SQLITE_OK is returned on success, or an sqlite error
+** code otherwise.
+**
+** If successful, the number of columns is written to *pnCol. *paCol is
+** set to point at sqlite3_malloc()'d space containing the array of
+** nCol column names. The caller is responsible for calling sqlite3_free
+** on *paCol.
+*/
+static int getColumnNames(
+  sqlite3 *db, 
+  const char *zTab,
+  char ***paCol, 
+  int *pnCol
+){
+  char **aCol = 0;
+  char *zSql;
+  sqlite3_stmt *pStmt = 0;
+  int rc = SQLITE_OK;
+  int nCol = 0;
+
+  /* Prepare the statement "SELECT * FROM <tbl>". The column names
+  ** of the result set of the compiled SELECT will be the same as
+  ** the column names of table <tbl>.
+  */
+  zSql = sqlite3_mprintf("SELECT * FROM %Q", zTab);
+  if( !zSql ){
+    rc = SQLITE_NOMEM;
+    goto out;
+  }
+  rc = sqlite3_prepare(db, zSql, -1, &pStmt, 0);
+  sqlite3_free(zSql);
+
+  if( rc==SQLITE_OK ){
+    int ii;
+    int nBytes;
+    char *zSpace;
+    nCol = sqlite3_column_count(pStmt);
+
+    /* Figure out how much space to allocate for the array of column names 
+    ** (including space for the strings themselves). Then allocate it.
+    */
+    nBytes = sizeof(char *) * nCol;
+    for(ii=0; ii<nCol; ii++){
+      const char *zName = sqlite3_column_name(pStmt, ii);
+      if( !zName ){
+        rc = SQLITE_NOMEM;
+        goto out;
+      }
+      nBytes += (int)strlen(zName)+1;
+    }
+    aCol = (char **)sqlite3MallocZero(nBytes);
+    if( !aCol ){
+      rc = SQLITE_NOMEM;
+      goto out;
+    }
+
+    /* Copy the column names into the allocated space and set up the
+    ** pointers in the aCol[] array.
+    */
+    zSpace = (char *)(&aCol[nCol]);
+    for(ii=0; ii<nCol; ii++){
+      aCol[ii] = zSpace;
+      sqlite3_snprintf(nBytes, zSpace, "%s", sqlite3_column_name(pStmt,ii));
+      zSpace += (int)strlen(zSpace) + 1;
+    }
+    assert( (zSpace-nBytes)==(char *)aCol );
+  }
+
+  *paCol = aCol;
+  *pnCol = nCol;
+
+out:
+  sqlite3_finalize(pStmt);
+  return rc;
+}
+
+/*
+** Parameter zTab is the name of a table in database db with nCol 
+** columns. This function allocates an array of integers nCol in 
+** size and populates it according to any implicit or explicit 
+** indices on table zTab.
+**
+** If successful, SQLITE_OK is returned and *paIndex set to point 
+** at the allocated array. Otherwise, an error code is returned.
+**
+** See comments associated with the member variable aIndex above 
+** "struct echo_vtab" for details of the contents of the array.
+*/
+static int getIndexArray(
+  sqlite3 *db,             /* Database connection */
+  const char *zTab,        /* Name of table in database db */
+  int nCol,
+  int **paIndex
+){
+  sqlite3_stmt *pStmt = 0;
+  int *aIndex = 0;
+  int rc;
+  char *zSql;
+
+  /* Allocate space for the index array */
+  aIndex = (int *)sqlite3MallocZero(sizeof(int) * nCol);
+  if( !aIndex ){
+    rc = SQLITE_NOMEM;
+    goto get_index_array_out;
+  }
+
+  /* Compile an sqlite pragma to loop through all indices on table zTab */
+  zSql = sqlite3_mprintf("PRAGMA index_list(%s)", zTab);
+  if( !zSql ){
+    rc = SQLITE_NOMEM;
+    goto get_index_array_out;
+  }
+  rc = sqlite3_prepare(db, zSql, -1, &pStmt, 0);
+  sqlite3_free(zSql);
+
+  /* For each index, figure out the left-most column and set the 
+  ** corresponding entry in aIndex[] to 1.
+  */
+  while( pStmt && sqlite3_step(pStmt)==SQLITE_ROW ){
+    const char *zIdx = (const char *)sqlite3_column_text(pStmt, 1);
+    sqlite3_stmt *pStmt2 = 0;
+    if( zIdx==0 ) continue;
+    zSql = sqlite3_mprintf("PRAGMA index_info(%s)", zIdx);
+    if( !zSql ){
+      rc = SQLITE_NOMEM;
+      goto get_index_array_out;
+    }
+    rc = sqlite3_prepare(db, zSql, -1, &pStmt2, 0);
+    sqlite3_free(zSql);
+    if( pStmt2 && sqlite3_step(pStmt2)==SQLITE_ROW ){
+      int cid = sqlite3_column_int(pStmt2, 1);
+      assert( cid>=0 && cid<nCol );
+      aIndex[cid] = 1;
+    }
+    if( pStmt2 ){
+      rc = sqlite3_finalize(pStmt2);
+    }
+    if( rc!=SQLITE_OK ){
+      goto get_index_array_out;
+    }
+  }
+
+
+get_index_array_out:
+  if( pStmt ){
+    int rc2 = sqlite3_finalize(pStmt);
+    if( rc==SQLITE_OK ){
+      rc = rc2;
+    }
+  }
+  if( rc!=SQLITE_OK ){
+    sqlite3_free(aIndex);
+    aIndex = 0;
+  }
+  *paIndex = aIndex;
+  return rc;
+}
+
+/*
+** Global Tcl variable $echo_module is a list. This routine appends
+** the string element zArg to that list in interpreter interp.
+*/
+static void appendToEchoModule(Tcl_Interp *interp, const char *zArg){
+  int flags = (TCL_APPEND_VALUE | TCL_LIST_ELEMENT | TCL_GLOBAL_ONLY);
+  Tcl_SetVar(interp, "echo_module", (zArg?zArg:""), flags);
+}
+
+/*
+** This function is called from within the echo-modules xCreate and
+** xConnect methods. The argc and argv arguments are copies of those 
+** passed to the calling method. This function is responsible for
+** calling sqlite3_declare_vtab() to declare the schema of the virtual
+** table being created or connected.
+**
+** If the constructor was passed just one argument, i.e.:
+**
+**   CREATE TABLE t1 AS echo(t2);
+**
+** Then t2 is assumed to be the name of a *real* database table. The
+** schema of the virtual table is declared by passing a copy of the 
+** CREATE TABLE statement for the real table to sqlite3_declare_vtab().
+** Hence, the virtual table should have exactly the same column names and 
+** types as the real table.
+*/
+static int echoDeclareVtab(
+  echo_vtab *pVtab, 
+  sqlite3 *db 
+){
+  int rc = SQLITE_OK;
+
+  if( pVtab->zTableName ){
+    sqlite3_stmt *pStmt = 0;
+    rc = sqlite3_prepare(db, 
+        "SELECT sql FROM sqlite_master WHERE type = 'table' AND name = ?",
+        -1, &pStmt, 0);
+    if( rc==SQLITE_OK ){
+      sqlite3_bind_text(pStmt, 1, pVtab->zTableName, -1, 0);
+      if( sqlite3_step(pStmt)==SQLITE_ROW ){
+        int rc2;
+        const char *zCreateTable = (const char *)sqlite3_column_text(pStmt, 0);
+        rc = sqlite3_declare_vtab(db, zCreateTable);
+        rc2 = sqlite3_finalize(pStmt);
+        if( rc==SQLITE_OK ){
+          rc = rc2;
+        }
+      } else {
+        rc = sqlite3_finalize(pStmt);
+        if( rc==SQLITE_OK ){ 
+          rc = SQLITE_ERROR;
+        }
+      }
+      if( rc==SQLITE_OK ){
+        rc = getColumnNames(db, pVtab->zTableName, &pVtab->aCol, &pVtab->nCol);
+      }
+      if( rc==SQLITE_OK ){
+        rc = getIndexArray(db, pVtab->zTableName, pVtab->nCol, &pVtab->aIndex);
+      }
+    }
+  }
+
+  return rc;
+}
+
+/*
+** This function frees all runtime structures associated with the virtual
+** table pVtab.
+*/
+static int echoDestructor(sqlite3_vtab *pVtab){
+  echo_vtab *p = (echo_vtab*)pVtab;
+  sqlite3_free(p->aIndex);
+  sqlite3_free(p->aCol);
+  sqlite3_free(p->zThis);
+  sqlite3_free(p->zTableName);
+  sqlite3_free(p->zLogName);
+  sqlite3_free(p);
+  return 0;
+}
+
+typedef struct EchoModule EchoModule;
+struct EchoModule {
+  Tcl_Interp *interp;
+};
+
+/*
+** This function is called to do the work of the xConnect() method -
+** to allocate the required in-memory structures for a newly connected
+** virtual table.
+*/
+static int echoConstructor(
+  sqlite3 *db,
+  void *pAux,
+  int argc, const char *const*argv,
+  sqlite3_vtab **ppVtab,
+  char **pzErr
+){
+  int rc;
+  int i;
+  echo_vtab *pVtab;
+
+  /* Allocate the sqlite3_vtab/echo_vtab structure itself */
+  pVtab = sqlite3MallocZero( sizeof(*pVtab) );
+  if( !pVtab ){
+    return SQLITE_NOMEM;
+  }
+  pVtab->interp = ((EchoModule *)pAux)->interp;
+  pVtab->db = db;
+
+  /* Allocate echo_vtab.zThis */
+  pVtab->zThis = sqlite3_mprintf("%s", argv[2]);
+  if( !pVtab->zThis ){
+    echoDestructor((sqlite3_vtab *)pVtab);
+    return SQLITE_NOMEM;
+  }
+
+  /* Allocate echo_vtab.zTableName */
+  if( argc>3 ){
+    pVtab->zTableName = sqlite3_mprintf("%s", argv[3]);
+    dequoteString(pVtab->zTableName);
+    if( pVtab->zTableName && pVtab->zTableName[0]=='*' ){
+      char *z = sqlite3_mprintf("%s%s", argv[2], &(pVtab->zTableName[1]));
+      sqlite3_free(pVtab->zTableName);
+      pVtab->zTableName = z;
+      pVtab->isPattern = 1;
+    }
+    if( !pVtab->zTableName ){
+      echoDestructor((sqlite3_vtab *)pVtab);
+      return SQLITE_NOMEM;
+    }
+  }
+
+  /* Log the arguments to this function to Tcl var ::echo_module */
+  for(i=0; i<argc; i++){
+    appendToEchoModule(pVtab->interp, argv[i]);
+  }
+
+  /* Invoke sqlite3_declare_vtab and set up other members of the echo_vtab
+  ** structure. If an error occurs, delete the sqlite3_vtab structure and
+  ** return an error code.
+  */
+  rc = echoDeclareVtab(pVtab, db);
+  if( rc!=SQLITE_OK ){
+    echoDestructor((sqlite3_vtab *)pVtab);
+    return rc;
+  }
+
+  /* Success. Set *ppVtab and return */
+  *ppVtab = &pVtab->base;
+  return SQLITE_OK;
+}
+
+/* 
+** Echo virtual table module xCreate method.
+*/
+static int echoCreate(
+  sqlite3 *db,
+  void *pAux,
+  int argc, const char *const*argv,
+  sqlite3_vtab **ppVtab,
+  char **pzErr
+){
+  int rc = SQLITE_OK;
+  appendToEchoModule(((EchoModule *)pAux)->interp, "xCreate");
+  rc = echoConstructor(db, pAux, argc, argv, ppVtab, pzErr);
+
+  /* If there were two arguments passed to the module at the SQL level 
+  ** (i.e. "CREATE VIRTUAL TABLE tbl USING echo(arg1, arg2)"), then 
+  ** the second argument is used as a table name. Attempt to create
+  ** such a table with a single column, "logmsg". This table will
+  ** be used to log calls to the xUpdate method. It will be deleted
+  ** when the virtual table is DROPed.
+  **
+  ** Note: The main point of this is to test that we can drop tables
+  ** from within an xDestroy method call.
+  */
+  if( rc==SQLITE_OK && argc==5 ){
+    char *zSql;
+    echo_vtab *pVtab = *(echo_vtab **)ppVtab;
+    pVtab->zLogName = sqlite3_mprintf("%s", argv[4]);
+    zSql = sqlite3_mprintf("CREATE TABLE %Q(logmsg)", pVtab->zLogName);
+    rc = sqlite3_exec(db, zSql, 0, 0, 0);
+    sqlite3_free(zSql);
+    if( rc!=SQLITE_OK ){
+      *pzErr = sqlite3_mprintf("%s", sqlite3_errmsg(db));
+    }
+  }
+
+  if( *ppVtab && rc!=SQLITE_OK ){
+    echoDestructor(*ppVtab);
+    *ppVtab = 0;
+  }
+
+  if( rc==SQLITE_OK ){
+    (*(echo_vtab**)ppVtab)->inTransaction = 1;
+  }
+
+  return rc;
+}
+
+/* 
+** Echo virtual table module xConnect method.
+*/
+static int echoConnect(
+  sqlite3 *db,
+  void *pAux,
+  int argc, const char *const*argv,
+  sqlite3_vtab **ppVtab,
+  char **pzErr
+){
+  appendToEchoModule(((EchoModule *)pAux)->interp, "xConnect");
+  return echoConstructor(db, pAux, argc, argv, ppVtab, pzErr);
+}
+
+/* 
+** Echo virtual table module xDisconnect method.
+*/
+static int echoDisconnect(sqlite3_vtab *pVtab){
+  appendToEchoModule(((echo_vtab *)pVtab)->interp, "xDisconnect");
+  return echoDestructor(pVtab);
+}
+
+/* 
+** Echo virtual table module xDestroy method.
+*/
+static int echoDestroy(sqlite3_vtab *pVtab){
+  int rc = SQLITE_OK;
+  echo_vtab *p = (echo_vtab *)pVtab;
+  appendToEchoModule(((echo_vtab *)pVtab)->interp, "xDestroy");
+
+  /* Drop the "log" table, if one exists (see echoCreate() for details) */
+  if( p && p->zLogName ){
+    char *zSql;
+    zSql = sqlite3_mprintf("DROP TABLE %Q", p->zLogName);
+    rc = sqlite3_exec(p->db, zSql, 0, 0, 0);
+    sqlite3_free(zSql);
+  }
+
+  if( rc==SQLITE_OK ){
+    rc = echoDestructor(pVtab);
+  }
+  return rc;
+}
+
+/* 
+** Echo virtual table module xOpen method.
+*/
+static int echoOpen(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor){
+  echo_cursor *pCur;
+  if( simulateVtabError((echo_vtab *)pVTab, "xOpen") ){
+    return SQLITE_ERROR;
+  }
+  pCur = sqlite3MallocZero(sizeof(echo_cursor));
+  *ppCursor = (sqlite3_vtab_cursor *)pCur;
+  return (pCur ? SQLITE_OK : SQLITE_NOMEM);
+}
+
+/* 
+** Echo virtual table module xClose method.
+*/
+static int echoClose(sqlite3_vtab_cursor *cur){
+  int rc;
+  echo_cursor *pCur = (echo_cursor *)cur;
+  sqlite3_stmt *pStmt = pCur->pStmt;
+  pCur->pStmt = 0;
+  sqlite3_free(pCur);
+  rc = sqlite3_finalize(pStmt);
+  return rc;
+}
+
+/*
+** Return non-zero if the cursor does not currently point to a valid record
+** (i.e if the scan has finished), or zero otherwise.
+*/
+static int echoEof(sqlite3_vtab_cursor *cur){
+  return (((echo_cursor *)cur)->pStmt ? 0 : 1);
+}
+
+/* 
+** Echo virtual table module xNext method.
+*/
+static int echoNext(sqlite3_vtab_cursor *cur){
+  int rc = SQLITE_OK;
+  echo_cursor *pCur = (echo_cursor *)cur;
+
+  if( simulateVtabError((echo_vtab *)(cur->pVtab), "xNext") ){
+    return SQLITE_ERROR;
+  }
+
+  if( pCur->pStmt ){
+    rc = sqlite3_step(pCur->pStmt);
+    if( rc==SQLITE_ROW ){
+      rc = SQLITE_OK;
+    }else{
+      rc = sqlite3_finalize(pCur->pStmt);
+      pCur->pStmt = 0;
+    }
+  }
+
+  return rc;
+}
+
+/* 
+** Echo virtual table module xColumn method.
+*/
+static int echoColumn(sqlite3_vtab_cursor *cur, sqlite3_context *ctx, int i){
+  int iCol = i + 1;
+  sqlite3_stmt *pStmt = ((echo_cursor *)cur)->pStmt;
+
+  if( simulateVtabError((echo_vtab *)(cur->pVtab), "xColumn") ){
+    return SQLITE_ERROR;
+  }
+
+  if( !pStmt ){
+    sqlite3_result_null(ctx);
+  }else{
+    assert( sqlite3_data_count(pStmt)>iCol );
+    sqlite3_result_value(ctx, sqlite3_column_value(pStmt, iCol));
+  }
+  return SQLITE_OK;
+}
+
+/* 
+** Echo virtual table module xRowid method.
+*/
+static int echoRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
+  sqlite3_stmt *pStmt = ((echo_cursor *)cur)->pStmt;
+
+  if( simulateVtabError((echo_vtab *)(cur->pVtab), "xRowid") ){
+    return SQLITE_ERROR;
+  }
+
+  *pRowid = sqlite3_column_int64(pStmt, 0);
+  return SQLITE_OK;
+}
+
+/*
+** Compute a simple hash of the null terminated string zString.
+**
+** This module uses only sqlite3_index_info.idxStr, not 
+** sqlite3_index_info.idxNum. So to test idxNum, when idxStr is set
+** in echoBestIndex(), idxNum is set to the corresponding hash value.
+** In echoFilter(), code assert()s that the supplied idxNum value is
+** indeed the hash of the supplied idxStr.
+*/
+static int hashString(const char *zString){
+  u32 val = 0;
+  int ii;
+  for(ii=0; zString[ii]; ii++){
+    val = (val << 3) + (int)zString[ii];
+  }
+  return (int)(val&0x7fffffff);
+}
+
+/* 
+** Echo virtual table module xFilter method.
+*/
+static int echoFilter(
+  sqlite3_vtab_cursor *pVtabCursor, 
+  int idxNum, const char *idxStr,
+  int argc, sqlite3_value **argv
+){
+  int rc;
+  int i;
+
+  echo_cursor *pCur = (echo_cursor *)pVtabCursor;
+  echo_vtab *pVtab = (echo_vtab *)pVtabCursor->pVtab;
+  sqlite3 *db = pVtab->db;
+
+  if( simulateVtabError(pVtab, "xFilter") ){
+    return SQLITE_ERROR;
+  }
+
+  /* Check that idxNum matches idxStr */
+  assert( idxNum==hashString(idxStr) );
+
+  /* Log arguments to the ::echo_module Tcl variable */
+  appendToEchoModule(pVtab->interp, "xFilter");
+  appendToEchoModule(pVtab->interp, idxStr);
+  for(i=0; i<argc; i++){
+    appendToEchoModule(pVtab->interp, (const char*)sqlite3_value_text(argv[i]));
+  }
+
+  sqlite3_finalize(pCur->pStmt);
+  pCur->pStmt = 0;
+
+  /* Prepare the SQL statement created by echoBestIndex and bind the
+  ** runtime parameters passed to this function to it.
+  */
+  rc = sqlite3_prepare(db, idxStr, -1, &pCur->pStmt, 0);
+  assert( pCur->pStmt || rc!=SQLITE_OK );
+  for(i=0; rc==SQLITE_OK && i<argc; i++){
+    rc = sqlite3_bind_value(pCur->pStmt, i+1, argv[i]);
+  }
+
+  /* If everything was successful, advance to the first row of the scan */
+  if( rc==SQLITE_OK ){
+    rc = echoNext(pVtabCursor);
+  }
+
+  return rc;
+}
+
+
+/*
+** A helper function used by echoUpdate() and echoBestIndex() for
+** manipulating strings in concert with the sqlite3_mprintf() function.
+**
+** Parameter pzStr points to a pointer to a string allocated with
+** sqlite3_mprintf. The second parameter, zAppend, points to another
+** string. The two strings are concatenated together and *pzStr
+** set to point at the result. The initial buffer pointed to by *pzStr
+** is deallocated via sqlite3_free().
+**
+** If the third argument, doFree, is true, then sqlite3_free() is
+** also called to free the buffer pointed to by zAppend.
+*/
+static void string_concat(char **pzStr, char *zAppend, int doFree, int *pRc){
+  char *zIn = *pzStr;
+  if( !zAppend && doFree && *pRc==SQLITE_OK ){
+    *pRc = SQLITE_NOMEM;
+  }
+  if( *pRc!=SQLITE_OK ){
+    sqlite3_free(zIn);
+    zIn = 0;
+  }else{
+    if( zIn ){
+      char *zTemp = zIn;
+      zIn = sqlite3_mprintf("%s%s", zIn, zAppend);
+      sqlite3_free(zTemp);
+    }else{
+      zIn = sqlite3_mprintf("%s", zAppend);
+    }
+    if( !zIn ){
+      *pRc = SQLITE_NOMEM;
+    }
+  }
+  *pzStr = zIn;
+  if( doFree ){
+    sqlite3_free(zAppend);
+  }
+}
+
+/*
+** This function returns a pointer to an sqlite3_malloc()ed buffer 
+** containing the select-list (the thing between keywords SELECT and FROM)
+** to query the underlying real table with for the scan described by
+** argument pIdxInfo.
+**
+** If the current SQLite version is earlier than 3.10.0, this is just "*"
+** (select all columns). Or, for version 3.10.0 and greater, the list of
+** columns identified by the pIdxInfo->colUsed mask.
+*/
+static char *echoSelectList(echo_vtab *pTab, sqlite3_index_info *pIdxInfo){
+  char *zRet = 0;
+  if( sqlite3_libversion_number()<3010000 ){
+    zRet = sqlite3_mprintf(", *");
+  }else{
+    int i;
+    for(i=0; i<pTab->nCol; i++){
+      if( pIdxInfo->colUsed & ((sqlite3_uint64)1 << (i>=63 ? 63 : i)) ){
+        zRet = sqlite3_mprintf("%z, %s", zRet, pTab->aCol[i]);
+      }else{
+        zRet = sqlite3_mprintf("%z, NULL", zRet);
+      }
+      if( !zRet ) break;
+    }
+  }
+  return zRet;
+}
+
+/*
+** The echo module implements the subset of query constraints and sort
+** orders that may take advantage of SQLite indices on the underlying
+** real table. For example, if the real table is declared as:
+**
+**     CREATE TABLE real(a, b, c);
+**     CREATE INDEX real_index ON real(b);
+**
+** then the echo module handles WHERE or ORDER BY clauses that refer
+** to the column "b", but not "a" or "c". If a multi-column index is
+** present, only its left most column is considered. 
+**
+** This xBestIndex method encodes the proposed search strategy as
+** an SQL query on the real table underlying the virtual echo module 
+** table and stores the query in sqlite3_index_info.idxStr. The SQL
+** statement is of the form:
+**
+**   SELECT rowid, * FROM <real-table> ?<where-clause>? ?<order-by-clause>?
+**
+** where the <where-clause> and <order-by-clause> are determined
+** by the contents of the structure pointed to by the pIdxInfo argument.
+*/
+static int echoBestIndex(sqlite3_vtab *tab, sqlite3_index_info *pIdxInfo){
+  int ii;
+  char *zQuery = 0;
+  char *zCol = 0;
+  char *zNew;
+  int nArg = 0;
+  const char *zSep = "WHERE";
+  echo_vtab *pVtab = (echo_vtab *)tab;
+  sqlite3_stmt *pStmt = 0;
+  Tcl_Interp *interp = pVtab->interp;
+
+  int nRow = 0;
+  int useIdx = 0;
+  int rc = SQLITE_OK;
+  int useCost = 0;
+  double cost = 0;
+  int isIgnoreUsable = 0;
+  if( Tcl_GetVar(interp, "echo_module_ignore_usable", TCL_GLOBAL_ONLY) ){
+    isIgnoreUsable = 1;
+  }
+
+  if( simulateVtabError(pVtab, "xBestIndex") ){
+    return SQLITE_ERROR;
+  }
+
+  /* Determine the number of rows in the table and store this value in local
+  ** variable nRow. The 'estimated-cost' of the scan will be the number of
+  ** rows in the table for a linear scan, or the log (base 2) of the 
+  ** number of rows if the proposed scan uses an index.  
+  */
+  if( Tcl_GetVar(interp, "echo_module_cost", TCL_GLOBAL_ONLY) ){
+    cost = atof(Tcl_GetVar(interp, "echo_module_cost", TCL_GLOBAL_ONLY));
+    useCost = 1;
+  } else {
+    zQuery = sqlite3_mprintf("SELECT count(*) FROM %Q", pVtab->zTableName);
+    if( !zQuery ){
+      return SQLITE_NOMEM;
+    }
+    rc = sqlite3_prepare(pVtab->db, zQuery, -1, &pStmt, 0);
+    sqlite3_free(zQuery);
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+    sqlite3_step(pStmt);
+    nRow = sqlite3_column_int(pStmt, 0);
+    rc = sqlite3_finalize(pStmt);
+    if( rc!=SQLITE_OK ){
+      return rc;
+    }
+  }
+
+  zCol = echoSelectList(pVtab, pIdxInfo);
+  if( !zCol ) return SQLITE_NOMEM;
+  zQuery = sqlite3_mprintf("SELECT rowid%z FROM %Q", zCol, pVtab->zTableName);
+  if( !zQuery ) return SQLITE_NOMEM;
+
+  for(ii=0; ii<pIdxInfo->nConstraint; ii++){
+    const struct sqlite3_index_constraint *pConstraint;
+    struct sqlite3_index_constraint_usage *pUsage;
+    int iCol;
+
+    pConstraint = &pIdxInfo->aConstraint[ii];
+    pUsage = &pIdxInfo->aConstraintUsage[ii];
+
+    if( !isIgnoreUsable && !pConstraint->usable ) continue;
+
+    iCol = pConstraint->iColumn;
+    if( iCol<0 || pVtab->aIndex[iCol] ){
+      char *zNewCol = iCol>=0 ? pVtab->aCol[iCol] : "rowid";
+      char *zOp = 0;
+      useIdx = 1;
+      switch( pConstraint->op ){
+        case SQLITE_INDEX_CONSTRAINT_EQ:
+          zOp = "="; break;
+        case SQLITE_INDEX_CONSTRAINT_LT:
+          zOp = "<"; break;
+        case SQLITE_INDEX_CONSTRAINT_GT:
+          zOp = ">"; break;
+        case SQLITE_INDEX_CONSTRAINT_LE:
+          zOp = "<="; break;
+        case SQLITE_INDEX_CONSTRAINT_GE:
+          zOp = ">="; break;
+        case SQLITE_INDEX_CONSTRAINT_MATCH:
+          /* Purposely translate the MATCH operator into a LIKE, which
+          ** will be used by the next block of code to construct a new
+          ** query.  It should also be noted here that the next block
+          ** of code requires the first letter of this operator to be
+          ** in upper-case to trigger the special MATCH handling (i.e.
+          ** wrapping the bound parameter with literal '%'s).
+          */
+          zOp = "LIKE"; break;
+        case SQLITE_INDEX_CONSTRAINT_LIKE:
+          zOp = "like"; break;
+        case SQLITE_INDEX_CONSTRAINT_GLOB:
+          zOp = "glob"; break;
+        case SQLITE_INDEX_CONSTRAINT_REGEXP:
+          zOp = "regexp"; break;
+      }
+      if( zOp[0]=='L' ){
+        zNew = sqlite3_mprintf(" %s %s LIKE (SELECT '%%'||?||'%%')", 
+                               zSep, zNewCol);
+      } else {
+        zNew = sqlite3_mprintf(" %s %s %s ?", zSep, zNewCol, zOp);
+      }
+      string_concat(&zQuery, zNew, 1, &rc);
+
+      zSep = "AND";
+      pUsage->argvIndex = ++nArg;
+      pUsage->omit = 1;
+    }
+  }
+
+  /* If there is only one term in the ORDER BY clause, and it is
+  ** on a column that this virtual table has an index for, then consume 
+  ** the ORDER BY clause.
+  */
+  if( pIdxInfo->nOrderBy==1 && (
+        pIdxInfo->aOrderBy->iColumn<0 ||
+        pVtab->aIndex[pIdxInfo->aOrderBy->iColumn]) ){
+    int iCol = pIdxInfo->aOrderBy->iColumn;
+    char *zNewCol = iCol>=0 ? pVtab->aCol[iCol] : "rowid";
+    char *zDir = pIdxInfo->aOrderBy->desc?"DESC":"ASC";
+    zNew = sqlite3_mprintf(" ORDER BY %s %s", zNewCol, zDir);
+    string_concat(&zQuery, zNew, 1, &rc);
+    pIdxInfo->orderByConsumed = 1;
+  }
+
+  appendToEchoModule(pVtab->interp, "xBestIndex");;
+  appendToEchoModule(pVtab->interp, zQuery);
+
+  if( !zQuery ){
+    return rc;
+  }
+  pIdxInfo->idxNum = hashString(zQuery);
+  pIdxInfo->idxStr = zQuery;
+  pIdxInfo->needToFreeIdxStr = 1;
+  if( useCost ){
+    pIdxInfo->estimatedCost = cost;
+  }else if( useIdx ){
+    /* Approximation of log2(nRow). */
+    for( ii=0; ii<(sizeof(int)*8)-1; ii++ ){
+      if( nRow & (1<<ii) ){
+        pIdxInfo->estimatedCost = (double)ii;
+      }
+    }
+  }else{
+    pIdxInfo->estimatedCost = (double)nRow;
+  }
+  return rc;
+}
+
+/*
+** The xUpdate method for echo module virtual tables.
+** 
+**    apData[0]  apData[1]  apData[2..]
+**
+**    INTEGER                              DELETE            
+**
+**    INTEGER    NULL       (nCol args)    UPDATE (do not set rowid)
+**    INTEGER    INTEGER    (nCol args)    UPDATE (with SET rowid = <arg1>)
+**
+**    NULL       NULL       (nCol args)    INSERT INTO (automatic rowid value)
+**    NULL       INTEGER    (nCol args)    INSERT (incl. rowid value)
+**
+*/
+int echoUpdate(
+  sqlite3_vtab *tab, 
+  int nData, 
+  sqlite3_value **apData, 
+  sqlite_int64 *pRowid
+){
+  echo_vtab *pVtab = (echo_vtab *)tab;
+  sqlite3 *db = pVtab->db;
+  int rc = SQLITE_OK;
+
+  sqlite3_stmt *pStmt = 0;
+  char *z = 0;               /* SQL statement to execute */
+  int bindArgZero = 0;       /* True to bind apData[0] to sql var no. nData */
+  int bindArgOne = 0;        /* True to bind apData[1] to sql var no. 1 */
+  int i;                     /* Counter variable used by for loops */
+
+  assert( nData==pVtab->nCol+2 || nData==1 );
+
+  /* Ticket #3083 - make sure we always start a transaction prior to
+  ** making any changes to a virtual table */
+  assert( pVtab->inTransaction );
+
+  if( simulateVtabError(pVtab, "xUpdate") ){
+    return SQLITE_ERROR;
+  }
+
+  /* If apData[0] is an integer and nData>1 then do an UPDATE */
+  if( nData>1 && sqlite3_value_type(apData[0])==SQLITE_INTEGER ){
+    char *zSep = " SET";
+    z = sqlite3_mprintf("UPDATE %Q", pVtab->zTableName);
+    if( !z ){
+      rc = SQLITE_NOMEM;
+    }
+
+    bindArgOne = (apData[1] && sqlite3_value_type(apData[1])==SQLITE_INTEGER);
+    bindArgZero = 1;
+
+    if( bindArgOne ){
+       string_concat(&z, " SET rowid=?1 ", 0, &rc);
+       zSep = ",";
+    }
+    for(i=2; i<nData; i++){
+      if( apData[i]==0 ) continue;
+      string_concat(&z, sqlite3_mprintf(
+          "%s %Q=?%d", zSep, pVtab->aCol[i-2], i), 1, &rc);
+      zSep = ",";
+    }
+    string_concat(&z, sqlite3_mprintf(" WHERE rowid=?%d", nData), 1, &rc);
+  }
+
+  /* If apData[0] is an integer and nData==1 then do a DELETE */
+  else if( nData==1 && sqlite3_value_type(apData[0])==SQLITE_INTEGER ){
+    z = sqlite3_mprintf("DELETE FROM %Q WHERE rowid = ?1", pVtab->zTableName);
+    if( !z ){
+      rc = SQLITE_NOMEM;
+    }
+    bindArgZero = 1;
+  }
+
+  /* If the first argument is NULL and there are more than two args, INSERT */
+  else if( nData>2 && sqlite3_value_type(apData[0])==SQLITE_NULL ){
+    int ii;
+    char *zInsert = 0;
+    char *zValues = 0;
+  
+    zInsert = sqlite3_mprintf("INSERT INTO %Q (", pVtab->zTableName);
+    if( !zInsert ){
+      rc = SQLITE_NOMEM;
+    }
+    if( sqlite3_value_type(apData[1])==SQLITE_INTEGER ){
+      bindArgOne = 1;
+      zValues = sqlite3_mprintf("?");
+      string_concat(&zInsert, "rowid", 0, &rc);
+    }
+
+    assert((pVtab->nCol+2)==nData);
+    for(ii=2; ii<nData; ii++){
+      string_concat(&zInsert, 
+          sqlite3_mprintf("%s%Q", zValues?", ":"", pVtab->aCol[ii-2]), 1, &rc);
+      string_concat(&zValues, 
+          sqlite3_mprintf("%s?%d", zValues?", ":"", ii), 1, &rc);
+    }
+
+    string_concat(&z, zInsert, 1, &rc);
+    string_concat(&z, ") VALUES(", 0, &rc);
+    string_concat(&z, zValues, 1, &rc);
+    string_concat(&z, ")", 0, &rc);
+  }
+
+  /* Anything else is an error */
+  else{
+    assert(0);
+    return SQLITE_ERROR;
+  }
+
+  if( rc==SQLITE_OK ){
+    rc = sqlite3_prepare(db, z, -1, &pStmt, 0);
+  }
+  assert( rc!=SQLITE_OK || pStmt );
+  sqlite3_free(z);
+  if( rc==SQLITE_OK ) {
+    if( bindArgZero ){
+      sqlite3_bind_value(pStmt, nData, apData[0]);
+    }
+    if( bindArgOne ){
+      sqlite3_bind_value(pStmt, 1, apData[1]);
+    }
+    for(i=2; i<nData && rc==SQLITE_OK; i++){
+      if( apData[i] ) rc = sqlite3_bind_value(pStmt, i, apData[i]);
+    }
+    if( rc==SQLITE_OK ){
+      sqlite3_step(pStmt);
+      rc = sqlite3_finalize(pStmt);
+    }else{
+      sqlite3_finalize(pStmt);
+    }
+  }
+
+  if( pRowid && rc==SQLITE_OK ){
+    *pRowid = sqlite3_last_insert_rowid(db);
+  }
+  if( rc!=SQLITE_OK ){
+    tab->zErrMsg = sqlite3_mprintf("echo-vtab-error: %s", sqlite3_errmsg(db));
+  }
+
+  return rc;
+}
+
+/*
+** xBegin, xSync, xCommit and xRollback callbacks for echo module
+** virtual tables. Do nothing other than add the name of the callback
+** to the $::echo_module Tcl variable.
+*/
+static int echoTransactionCall(sqlite3_vtab *tab, const char *zCall){
+  char *z;
+  echo_vtab *pVtab = (echo_vtab *)tab;
+  z = sqlite3_mprintf("echo(%s)", pVtab->zTableName);
+  if( z==0 ) return SQLITE_NOMEM;
+  appendToEchoModule(pVtab->interp, zCall);
+  appendToEchoModule(pVtab->interp, z);
+  sqlite3_free(z);
+  return SQLITE_OK;
+}
+static int echoBegin(sqlite3_vtab *tab){
+  int rc;
+  echo_vtab *pVtab = (echo_vtab *)tab;
+  Tcl_Interp *interp = pVtab->interp;
+  const char *zVal; 
+
+  /* Ticket #3083 - do not start a transaction if we are already in
+  ** a transaction */
+  assert( !pVtab->inTransaction );
+
+  if( simulateVtabError(pVtab, "xBegin") ){
+    return SQLITE_ERROR;
+  }
+
+  rc = echoTransactionCall(tab, "xBegin");
+
+  if( rc==SQLITE_OK ){
+    /* Check if the $::echo_module_begin_fail variable is defined. If it is,
+    ** and it is set to the name of the real table underlying this virtual
+    ** echo module table, then cause this xSync operation to fail.
+    */
+    zVal = Tcl_GetVar(interp, "echo_module_begin_fail", TCL_GLOBAL_ONLY);
+    if( zVal && 0==strcmp(zVal, pVtab->zTableName) ){
+      rc = SQLITE_ERROR;
+    }
+  }
+  if( rc==SQLITE_OK ){
+    pVtab->inTransaction = 1;
+  }
+  return rc;
+}
+static int echoSync(sqlite3_vtab *tab){
+  int rc;
+  echo_vtab *pVtab = (echo_vtab *)tab;
+  Tcl_Interp *interp = pVtab->interp;
+  const char *zVal; 
+
+  /* Ticket #3083 - Only call xSync if we have previously started a
+  ** transaction */
+  assert( pVtab->inTransaction );
+
+  if( simulateVtabError(pVtab, "xSync") ){
+    return SQLITE_ERROR;
+  }
+
+  rc = echoTransactionCall(tab, "xSync");
+
+  if( rc==SQLITE_OK ){
+    /* Check if the $::echo_module_sync_fail variable is defined. If it is,
+    ** and it is set to the name of the real table underlying this virtual
+    ** echo module table, then cause this xSync operation to fail.
+    */
+    zVal = Tcl_GetVar(interp, "echo_module_sync_fail", TCL_GLOBAL_ONLY);
+    if( zVal && 0==strcmp(zVal, pVtab->zTableName) ){
+      rc = -1;
+    }
+  }
+  return rc;
+}
+static int echoCommit(sqlite3_vtab *tab){
+  echo_vtab *pVtab = (echo_vtab*)tab;
+  int rc;
+
+  /* Ticket #3083 - Only call xCommit if we have previously started
+  ** a transaction */
+  assert( pVtab->inTransaction );
+
+  if( simulateVtabError(pVtab, "xCommit") ){
+    return SQLITE_ERROR;
+  }
+
+  sqlite3BeginBenignMalloc();
+  rc = echoTransactionCall(tab, "xCommit");
+  sqlite3EndBenignMalloc();
+  pVtab->inTransaction = 0;
+  return rc;
+}
+static int echoRollback(sqlite3_vtab *tab){
+  int rc;
+  echo_vtab *pVtab = (echo_vtab*)tab;
+
+  /* Ticket #3083 - Only call xRollback if we have previously started
+  ** a transaction */
+  assert( pVtab->inTransaction );
+
+  rc = echoTransactionCall(tab, "xRollback");
+  pVtab->inTransaction = 0;
+  return rc;
+}
+
+/*
+** Implementation of "GLOB" function on the echo module.  Pass
+** all arguments to the ::echo_glob_overload procedure of TCL
+** and return the result of that procedure as a string.
+*/
+static void overloadedGlobFunction(
+  sqlite3_context *pContext,
+  int nArg,
+  sqlite3_value **apArg
+){
+  Tcl_Interp *interp = sqlite3_user_data(pContext);
+  Tcl_DString str;
+  int i;
+  int rc;
+  Tcl_DStringInit(&str);
+  Tcl_DStringAppendElement(&str, "::echo_glob_overload");
+  for(i=0; i<nArg; i++){
+    Tcl_DStringAppendElement(&str, (char*)sqlite3_value_text(apArg[i]));
+  }
+  rc = Tcl_Eval(interp, Tcl_DStringValue(&str));
+  Tcl_DStringFree(&str);
+  if( rc ){
+    sqlite3_result_error(pContext, Tcl_GetStringResult(interp), -1);
+  }else{
+    sqlite3_result_text(pContext, Tcl_GetStringResult(interp),
+                        -1, SQLITE_TRANSIENT);
+  }
+  Tcl_ResetResult(interp);
+}
+
+/*
+** This is the xFindFunction implementation for the echo module.
+** SQLite calls this routine when the first argument of a function
+** is a column of an echo virtual table.  This routine can optionally
+** override the implementation of that function.  It will choose to
+** do so if the function is named "glob", and a TCL command named
+** ::echo_glob_overload exists.
+*/
+static int echoFindFunction(
+  sqlite3_vtab *vtab,
+  int nArg,
+  const char *zFuncName,
+  void (**pxFunc)(sqlite3_context*,int,sqlite3_value**),
+  void **ppArg
+){
+  echo_vtab *pVtab = (echo_vtab *)vtab;
+  Tcl_Interp *interp = pVtab->interp;
+  Tcl_CmdInfo info;
+  if( strcmp(zFuncName,"glob")!=0 ){
+    return 0;
+  }
+  if( Tcl_GetCommandInfo(interp, "::echo_glob_overload", &info)==0 ){
+    return 0;
+  }
+  *pxFunc = overloadedGlobFunction;
+  *ppArg = interp;
+  return 1;
+}
+
+static int echoRename(sqlite3_vtab *vtab, const char *zNewName){
+  int rc = SQLITE_OK;
+  echo_vtab *p = (echo_vtab *)vtab;
+
+  if( simulateVtabError(p, "xRename") ){
+    return SQLITE_ERROR;
+  }
+
+  if( p->isPattern ){
+    int nThis = (int)strlen(p->zThis);
+    char *zSql = sqlite3_mprintf("ALTER TABLE %s RENAME TO %s%s", 
+        p->zTableName, zNewName, &p->zTableName[nThis]
+    );
+    rc = sqlite3_exec(p->db, zSql, 0, 0, 0);
+    sqlite3_free(zSql);
+  }
+
+  return rc;
+}
+
+static int echoSavepoint(sqlite3_vtab *pVTab, int iSavepoint){
+  assert( pVTab );
+  return SQLITE_OK;
+}
+
+static int echoRelease(sqlite3_vtab *pVTab, int iSavepoint){
+  assert( pVTab );
+  return SQLITE_OK;
+}
+
+static int echoRollbackTo(sqlite3_vtab *pVTab, int iSavepoint){
+  assert( pVTab );
+  return SQLITE_OK;
+}
+
+/*
+** A virtual table module that merely "echos" the contents of another
+** table (like an SQL VIEW).
+*/
+static sqlite3_module echoModule = {
+  1,                         /* iVersion */
+  echoCreate,
+  echoConnect,
+  echoBestIndex,
+  echoDisconnect, 
+  echoDestroy,
+  echoOpen,                  /* xOpen - open a cursor */
+  echoClose,                 /* xClose - close a cursor */
+  echoFilter,                /* xFilter - configure scan constraints */
+  echoNext,                  /* xNext - advance a cursor */
+  echoEof,                   /* xEof */
+  echoColumn,                /* xColumn - read data */
+  echoRowid,                 /* xRowid - read data */
+  echoUpdate,                /* xUpdate - write data */
+  echoBegin,                 /* xBegin - begin transaction */
+  echoSync,                  /* xSync - sync transaction */
+  echoCommit,                /* xCommit - commit transaction */
+  echoRollback,              /* xRollback - rollback transaction */
+  echoFindFunction,          /* xFindFunction - function overloading */
+  echoRename                 /* xRename - rename the table */
+};
+
+static sqlite3_module echoModuleV2 = {
+  2,                         /* iVersion */
+  echoCreate,
+  echoConnect,
+  echoBestIndex,
+  echoDisconnect, 
+  echoDestroy,
+  echoOpen,                  /* xOpen - open a cursor */
+  echoClose,                 /* xClose - close a cursor */
+  echoFilter,                /* xFilter - configure scan constraints */
+  echoNext,                  /* xNext - advance a cursor */
+  echoEof,                   /* xEof */
+  echoColumn,                /* xColumn - read data */
+  echoRowid,                 /* xRowid - read data */
+  echoUpdate,                /* xUpdate - write data */
+  echoBegin,                 /* xBegin - begin transaction */
+  echoSync,                  /* xSync - sync transaction */
+  echoCommit,                /* xCommit - commit transaction */
+  echoRollback,              /* xRollback - rollback transaction */
+  echoFindFunction,          /* xFindFunction - function overloading */
+  echoRename,                /* xRename - rename the table */
+  echoSavepoint,
+  echoRelease,
+  echoRollbackTo
+};
+
+/*
+** Decode a pointer to an sqlite3 object.
+*/
+extern int getDbPointer(Tcl_Interp *interp, const char *zA, sqlite3 **ppDb);
+extern const char *sqlite3ErrName(int);
+
+static void moduleDestroy(void *p){
+  sqlite3_free(p);
+}
+
+/*
+** Register the echo virtual table module.
+*/
+static int SQLITE_TCLAPI register_echo_module(
+  ClientData clientData, /* Pointer to sqlite3_enable_XXX function */
+  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
+  int objc,              /* Number of arguments */
+  Tcl_Obj *CONST objv[]  /* Command arguments */
+){
+  int rc;
+  sqlite3 *db;
+  EchoModule *pMod;
+  if( objc!=2 ){
+    Tcl_WrongNumArgs(interp, 1, objv, "DB");
+    return TCL_ERROR;
+  }
+  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ) return TCL_ERROR;
+
+  /* Virtual table module "echo" */
+  pMod = sqlite3_malloc(sizeof(EchoModule));
+  pMod->interp = interp;
+  rc = sqlite3_create_module_v2(
+      db, "echo", &echoModule, (void*)pMod, moduleDestroy
+  );
+
+  /* Virtual table module "echo_v2" */
+  if( rc==SQLITE_OK ){
+    pMod = sqlite3_malloc(sizeof(EchoModule));
+    pMod->interp = interp;
+    rc = sqlite3_create_module_v2(db, "echo_v2", 
+        &echoModuleV2, (void*)pMod, moduleDestroy
+    );
+  }
+
+  Tcl_SetResult(interp, (char *)sqlite3ErrName(rc), TCL_STATIC);
+  return TCL_OK;
+}
+
+/*
+** Tcl interface to sqlite3_declare_vtab, invoked as follows from Tcl:
+**
+** sqlite3_declare_vtab DB SQL
+*/
+static int SQLITE_TCLAPI declare_vtab(
+  ClientData clientData, /* Pointer to sqlite3_enable_XXX function */
+  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
+  int objc,              /* Number of arguments */
+  Tcl_Obj *CONST objv[]  /* Command arguments */
+){
+  sqlite3 *db;
+  int rc;
+  if( objc!=3 ){
+    Tcl_WrongNumArgs(interp, 1, objv, "DB SQL");
+    return TCL_ERROR;
+  }
+  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ) return TCL_ERROR;
+  rc = sqlite3_declare_vtab(db, Tcl_GetString(objv[2]));
+  if( rc!=SQLITE_OK ){
+    Tcl_SetResult(interp, (char *)sqlite3_errmsg(db), TCL_VOLATILE);
+    return TCL_ERROR;
+  }
+  return TCL_OK;
+}
+
+#endif /* ifndef SQLITE_OMIT_VIRTUALTABLE */
+
+/*
+** Register commands with the TCL interpreter.
+*/
+int Sqlitetest8_Init(Tcl_Interp *interp){
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+  static struct {
+     char *zName;
+     Tcl_ObjCmdProc *xProc;
+     void *clientData;
+  } aObjCmd[] = {
+     { "register_echo_module",       register_echo_module, 0 },
+     { "sqlite3_declare_vtab",       declare_vtab, 0 },
+  };
+  int i;
+  for(i=0; i<sizeof(aObjCmd)/sizeof(aObjCmd[0]); i++){
+    Tcl_CreateObjCommand(interp, aObjCmd[i].zName, 
+        aObjCmd[i].xProc, aObjCmd[i].clientData, 0);
+  }
+#endif
+  return TCL_OK;
+}