SQLite

    u8 orphanTrigger;           /* Last statement is orphaned TEMP trigger */
    u8 imposterTable;           /* Building an imposter table */
  } init;
  int nVdbeActive;              /* Number of VDBEs currently running */
  int nVdbeRead;                /* Number of active VDBEs that read or write */
  int nVdbeWrite;               /* Number of active VDBEs that read and write */
  int nVdbeExec;                /* Number of nested calls to VdbeExec() */

  int nExtension;               /* Number of loaded extensions */
  void **aExtension;            /* Array of shared library handles */
  void (*xTrace)(void*,const char*);        /* Trace function */
  void *pTraceArg;                          /* Argument to the trace function */
  void (*xProfile)(void*,const char*,u64);  /* Profiling function */
  void *pProfileArg;                        /* Argument to profile function */
  void *pCommitArg;                 /* Argument to xCommitCallback() */   

** the last one in the database) then a zero is stored in register P2.
** If AUTOVACUUM is disabled then a zero is stored in register P2.
**
** See also: Clear
*/
case OP_Destroy: {     /* out2-prerelease */
  int iMoved;
  int iCnt;
  Vdbe *pVdbe;
  int iDb;

  assert( p->readOnly==0 );
#ifndef SQLITE_OMIT_VIRTUALTABLE
  iCnt = 0;
  for(pVdbe=db->pVdbe; pVdbe; pVdbe = pVdbe->pNext){
    if( pVdbe->magic==VDBE_MAGIC_RUN && pVdbe->bIsReader 
     && pVdbe->inVtabMethod<2 && pVdbe->pc>=0 
    ){
      iCnt++;
    }
  }
#else
  iCnt = db->nVdbeRead;
#endif
  pOut->flags = MEM_Null;
  if( iCnt>1 ){
    rc = SQLITE_LOCKED;
    p->errorAction = OE_Abort;
  }else{
    iDb = pOp->p3;
    assert( iCnt==1 );
    assert( DbMaskTest(p->btreeMask, iDb) );
    iMoved = 0;  /* Not needed.  Only to silence a warning. */
    rc = sqlite3BtreeDropTable(db->aDb[iDb].pBt, pOp->p1, &iMoved);
    pOut->flags = MEM_Int;
    pOut->u.i = iMoved;
#ifndef SQLITE_OMIT_AUTOVACUUM
    if( rc==SQLITE_OK && iMoved!=0 ){

#ifndef SQLITE_OMIT_VIRTUALTABLE
/* Opcode: VDestroy P1 * * P4 *
**
** P4 is the name of a virtual table in database P1.  Call the xDestroy method
** of that table.
*/
case OP_VDestroy: {
  p->inVtabMethod = 2;
  rc = sqlite3VtabCallDestroy(db, pOp->p1, pOp->p4.z);
  p->inVtabMethod = 0;
  break;
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */

#ifndef SQLITE_OMIT_VIRTUALTABLE
/* Opcode: VOpen P1 * * P4 *
**

  {
    res = 0;
    apArg = p->apArg;
    for(i = 0; i<nArg; i++){
      apArg[i] = &pArgc[i+1];
    }

    p->inVtabMethod = 1;
    rc = pModule->xFilter(pVtabCursor, iQuery, pOp->p4.z, nArg, apArg);
    p->inVtabMethod = 0;
    sqlite3VtabImportErrmsg(p, pVtab);
    if( rc==SQLITE_OK ){
      res = pModule->xEof(pVtabCursor);
    }
    VdbeBranchTaken(res!=0,2);
    if( res ){
      pc = pOp->p2 - 1;

  /* Invoke the xNext() method of the module. There is no way for the
  ** underlying implementation to return an error if one occurs during
  ** xNext(). Instead, if an error occurs, true is returned (indicating that 
  ** data is available) and the error code returned when xColumn or
  ** some other method is next invoked on the save virtual table cursor.
  */
  p->inVtabMethod = 1;
  rc = pModule->xNext(pCur->pVtabCursor);
  p->inVtabMethod = 0;
  sqlite3VtabImportErrmsg(p, pVtab);
  if( rc==SQLITE_OK ){
    res = pModule->xEof(pCur->pVtabCursor);
  }
  VdbeBranchTaken(!res,2);
  if( !res ){
    /* If there is data, jump to P2 */

/*
** An instance of the virtual machine.  This structure contains the complete
** state of the virtual machine.
**
** The "sqlite3_stmt" structure pointer that is returned by sqlite3_prepare()
** is really a pointer to an instance of this structure.
**
** The Vdbe.inVtabMethod variable is set to non-zero for the duration of
** any virtual table method invocations made by the vdbe program. It is
** set to 2 for xDestroy method calls and 1 for all other methods. This
** variable is used for two purposes: to allow xDestroy methods to execute
** "DROP TABLE" statements and to prevent some nasty side effects of
** malloc failure when SQLite is invoked recursively by a virtual table 
** method function.
*/
struct Vdbe {
  sqlite3 *db;            /* The database connection that owns this statement */
  Op *aOp;                /* Space to hold the virtual machine's program */
  Mem *aMem;              /* The memory locations */
  Mem **apArg;            /* Arguments to currently executing user function */
  Mem *aColName;          /* Column names to return */

#ifdef SQLITE_DEBUG
  int rcApp;              /* errcode set by sqlite3_result_error_code() */
#endif
  u16 nResColumn;         /* Number of columns in one row of the result set */
  u8 errorAction;         /* Recovery action to do in case of an error */
  u8 minWriteFileFormat;  /* Minimum file format for writable database files */
  bft explain:2;          /* True if EXPLAIN present on SQL command */
  bft inVtabMethod:2;     /* See comments above */
  bft changeCntOn:1;      /* True to update the change-counter */
  bft expired:1;          /* True if the VM needs to be recompiled */
  bft runOnlyOnce:1;      /* Automatically expire on reset */
  bft usesStmtJournal:1;  /* True if uses a statement journal */
  bft readOnly:1;         /* True for statements that do not write */
  bft bIsReader:1;        /* True for statements that read */
  bft isPrepareV2:1;      /* True if prepared with prepare_v2() */

  }else if( pCx->pCursor ){
    sqlite3BtreeCloseCursor(pCx->pCursor);
  }
#ifndef SQLITE_OMIT_VIRTUALTABLE
  else if( pCx->pVtabCursor ){
    sqlite3_vtab_cursor *pVtabCursor = pCx->pVtabCursor;
    const sqlite3_module *pModule = pVtabCursor->pVtab->pModule;
    p->inVtabMethod = 1;
    pModule->xClose(pVtabCursor);
    p->inVtabMethod = 0;
  }
#endif
}

/*
** 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