SQLite

  }

  assert( pExpr->op==TK_COLUMN || pExpr->op==TK_TRIGGER );
  if( pExpr->op==TK_TRIGGER ){
    pTab = pParse->pTriggerTab;
  }else{
    assert( pTabList );
    for(iSrc=0; ALWAYS(iSrc<pTabList->nSrc); iSrc++){
      if( pExpr->iTable==pTabList->a[iSrc].iCursor ){
        pTab = pTabList->a[iSrc].pTab;
        break;
      }
    }
  }
  iCol = pExpr->iColumn;

** If the seekResult parameter is non-zero, then a successful call to
** MovetoUnpacked() to seek cursor pCur to (pKey, nKey) has already
** been performed. seekResult is the search result returned (a negative
** number if pCur points at an entry that is smaller than (pKey, nKey), or
** a positive value if pCur points at an etry that is larger than 
** (pKey, nKey)). 
**
** If the seekResult parameter is non-zero, then the caller guarantees that
** cursor pCur is pointing at the existing copy of a row that is to be
** overwritten.  If the seekResult parameter is 0, then cursor pCur may
** point to any entry or to no entry at all and so this function has to seek
** the cursor before the new key can be inserted.
*/
int sqlite3BtreeInsert(
  BtCursor *pCur,                /* Insert data into the table of this cursor */
  const void *pKey, i64 nKey,    /* The key of the new record */
  const void *pData, int nData,  /* The data of the new record */
  int nZero,                     /* Number of extra 0 bytes to append to data */
  int appendBias,                /* True if this is likely an append */
  int seekResult                 /* Result of prior MovetoUnpacked() call */
){
  int rc;
  int loc = seekResult;          /* -1: before desired location  +1: after */
  int szNew;
  int idx;
  MemPage *pPage;
  Btree *p = pCur->pBtree;
  BtShared *pBt = p->pBt;
  unsigned char *oldCell;
  unsigned char *newCell = 0;

  int eDest = pDest->eDest;
  int iParm = pDest->iParm;

  int regRow;
  int regRowid;

  iTab = pOrderBy->iECursor;
  regRow = sqlite3GetTempReg(pParse);
  if( eDest==SRT_Output || eDest==SRT_Coroutine ){
    pseudoTab = pParse->nTab++;
    sqlite3VdbeAddOp3(v, OP_OpenPseudo, pseudoTab, regRow, nColumn);
    regRowid = 0;
  }else{
    regRowid = sqlite3GetTempReg(pParse);
  }
  addr = 1 + sqlite3VdbeAddOp2(v, OP_Sort, iTab, addrBreak);
  codeOffset(v, p, addrContinue);


  sqlite3VdbeAddOp3(v, OP_Column, iTab, pOrderBy->nExpr + 1, regRow);
  switch( eDest ){
    case SRT_Table:
    case SRT_EphemTab: {
      testcase( eDest==SRT_Table );
      testcase( eDest==SRT_EphemTab );
      sqlite3VdbeAddOp2(v, OP_NewRowid, iParm, regRowid);

    }
#endif
    default: {
      int i;
      assert( eDest==SRT_Output || eDest==SRT_Coroutine ); 
      testcase( eDest==SRT_Output );
      testcase( eDest==SRT_Coroutine );


      for(i=0; i<nColumn; i++){
        assert( regRow!=pDest->iMem+i );
        sqlite3VdbeAddOp3(v, OP_Column, pseudoTab, i, pDest->iMem+i);
        if( i==0 ){
          sqlite3VdbeChangeP5(v, OPFLAG_CLEARCACHE);
        }
      }
      if( eDest==SRT_Output ){
        sqlite3VdbeAddOp2(v, OP_ResultRow, pDest->iMem, nColumn);
        sqlite3ExprCacheAffinityChange(pParse, pDest->iMem, nColumn);
      }else{
        sqlite3VdbeAddOp1(v, OP_Yield, pDest->iParm);
      }

  const char *zAuthContext;   /* Put saved Parse.zAuthContext here */
  Parse *pParse;              /* The Parse structure */
};

/*
** Bitfield flags for P5 value in OP_Insert and OP_Delete
*/
#define OPFLAG_NCHANGE       0x01    /* Set to update db->nChange */
#define OPFLAG_LASTROWID     0x02    /* Set to update db->lastRowid */
#define OPFLAG_ISUPDATE      0x04    /* This OP_Insert is an sql UPDATE */
#define OPFLAG_APPEND        0x08    /* This is likely to be an append */
#define OPFLAG_USESEEKRESULT 0x10    /* Try to avoid a seek in BtreeInsert() */
#define OPFLAG_CLEARCACHE    0x20    /* Clear pseudo-table cache in OP_Column */

/*
 * Each trigger present in the database schema is stored as an instance of
 * struct Trigger. 
 *
 * Pointers to instances of struct Trigger are stored in two ways.
 * 1. In the "trigHash" hash table (part of the sqlite3* that represents the 

** if we run out of memory.
*/
static VdbeCursor *allocateCursor(
  Vdbe *p,              /* The virtual machine */
  int iCur,             /* Index of the new VdbeCursor */
  int nField,           /* Number of fields in the table or index */
  int iDb,              /* When database the cursor belongs to, or -1 */
  int isBtreeCursor     /* True for B-Tree.  False for pseudo-table or vtab */
){
  /* Find the memory cell that will be used to store the blob of memory
  ** required for this VdbeCursor structure. It is convenient to use a 
  ** vdbe memory cell to manage the memory allocation required for a
  ** VdbeCursor structure for the following reasons:
  **
  **   * Sometimes cursor numbers are used for a couple of different

case OP_NotNull: {            /* same as TK_NOTNULL, jump, in1 */
  if( (pIn1->flags & MEM_Null)==0 ){
    pc = pOp->p2 - 1;
  }
  break;
}























/* Opcode: Column P1 P2 P3 P4 P5
**
** Interpret the data that cursor P1 points to as a structure built using
** the MakeRecord instruction.  (See the MakeRecord opcode for additional
** information about the format of the data.)  Extract the P2-th column
** from this record.  If there are less that (P2+1) 
** values in the record, extract a NULL.
**
** The value extracted is stored in register P3.
**
** If the column contains fewer than P2 fields, then extract a NULL.  Or,
** if the P4 argument is a P4_MEM use the value of the P4 argument as
** the result.
**
** If the OPFLAG_CLEARCACHE bit is set on P5 and P1 is a pseudo-table cursor,
** then the cache of the cursor is reset prior to extracting the column.
** The first OP_Column against a pseudo-table after the value of the content
** register has changed should have this bit set.
*/
case OP_Column: {
  u32 payloadSize;   /* Number of bytes in the record */
  i64 payloadSize64; /* Number of bytes in the record */
  int p1;            /* P1 value of the opcode */
  int p2;            /* column number to retrieve */
  VdbeCursor *pC;    /* The VDBE cursor */

  Mem sMem;          /* For storing the record being decoded */
  u8 *zIdx;          /* Index into header */
  u8 *zEndHdr;       /* Pointer to first byte after the header */
  u32 offset;        /* Offset into the data */
  u64 offset64;      /* 64-bit offset.  64 bits needed to catch overflow */
  int szHdr;         /* Size of the header size field at start of record */
  int avail;         /* Number of bytes of available data */
  Mem *pReg;         /* PseudoTable input register */


  p1 = pOp->p1;
  p2 = pOp->p2;
  pC = 0;
  memset(&sMem, 0, sizeof(sMem));
  assert( p1<p->nCursor );

      assert( (payloadSize64 & SQLITE_MAX_U32)==(u64)payloadSize64 );
      payloadSize = (u32)payloadSize64;
    }else{
      assert( sqlite3BtreeCursorIsValid(pCrsr) );
      rc = sqlite3BtreeDataSize(pCrsr, &payloadSize);
      assert( rc==SQLITE_OK );   /* DataSize() cannot fail */
    }
  }else if( pC->pseudoTableReg>0 ){
    pReg = &p->aMem[pC->pseudoTableReg];
    assert( pReg->flags & MEM_Blob );
    payloadSize = pReg->n;
    zRec = pReg->z;
    pC->cacheStatus = (pOp->p5&OPFLAG_CLEARCACHE) ? CACHE_STALE : p->cacheCtr;
    assert( payloadSize==0 || zRec!=0 );
  }else{
    /* Consider the row to be NULL */
    payloadSize = 0;
  }

  /* If payloadSize is 0, then just store a NULL */

  pCx->isIndex = !pCx->isTable;
  break;
}

/* Opcode: OpenPseudo P1 P2 P3 * *
**
** Open a new cursor that points to a fake table that contains a single
** row of data.  The content of that one row in the content of memory
** register P2.  In other words, cursor P1 becomes an alias for the 
** MEM_Blob content contained in register P2.
**
** A pseudo-table created by this opcode is used to hold the a single

** row output from the sorter so that the row can be decomposed into
** individual columns using the OP_Column opcode.  The OP_Column opcode


** is the only cursor opcode that works with a pseudo-table.





**
** P3 is the number of fields in the records that will be stored by
** the pseudo-table.
*/
case OP_OpenPseudo: {
  VdbeCursor *pCx;

  assert( pOp->p1>=0 );
  pCx = allocateCursor(p, pOp->p1, pOp->p3, -1, 0);
  if( pCx==0 ) goto no_mem;
  pCx->nullRow = 1;
  pCx->pseudoTableReg = pOp->p2;

  pCx->isTable = 1;
  pCx->isIndex = 0;
  break;
}

/* Opcode: Close P1 * * * *
**

  int nField;
  i64 iKey;      /* The rowid we are to seek to */

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  assert( pOp->p2!=0 );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  assert( pC->pseudoTableReg==0 );
  if( pC->pCursor!=0 ){
    oc = pOp->opcode;
    pC->nullRow = 0;
    if( pC->isTable ){
      /* The input value in P3 might be of any type: integer, real, string,
      ** blob, or NULL.  But it needs to be an integer before we can do
      ** the seek, so covert it. */

      pc = pOp->p2 - 1;
    }
  }else{
    /* This happens when attempting to open the sqlite3_master table
    ** for read access returns SQLITE_EMPTY. In this case always
    ** take the jump (since there are no records in the table).
    */

    pc = pOp->p2 - 1;
  }
  break;
}

/* Opcode: Seek P1 P2 * * *
**

  u64 iKey;

  assert( pIn3->flags & MEM_Int );
  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  assert( pC->isTable );
  assert( pC->pseudoTableReg==0 );
  pCrsr = pC->pCursor;
  if( pCrsr!=0 ){
    res = 0;
    iKey = pIn3->u.i;
    rc = sqlite3BtreeMovetoUnpacked(pCrsr, 0, iKey, 0, &res);
    pC->lastRowid = pIn3->u.i;
    pC->rowidIsValid = res==0 ?1:0;
    pC->nullRow = 0;
    pC->cacheStatus = CACHE_STALE;
    pC->deferredMoveto = 0;
    if( res!=0 ){
      pc = pOp->p2 - 1;
      assert( pC->rowidIsValid==0 );
    }
    pC->seekResult = res;
  }else{
    /* This happens when an attempt to open a read cursor on the 
    ** sqlite_master table returns SQLITE_EMPTY.
    */


    pc = pOp->p2 - 1;
    assert( pC->rowidIsValid==0 );
    pC->seekResult = 0;
  }
  break;
}

  break;
}

/* Opcode: Insert P1 P2 P3 P4 P5
**
** Write an entry into the table of cursor P1.  A new entry is
** created if it doesn't already exist or the data for an existing
** entry is overwritten.  The data is the value MEM_Blob stored in register
** number P2. The key is stored in register P3. The key must
** be a MEM_Int.
**
** If the OPFLAG_NCHANGE flag of P5 is set, then the row change count is
** incremented (otherwise not).  If the OPFLAG_LASTROWID flag of P5 is set,
** then rowid is stored for subsequent return by the
** sqlite3_last_insert_rowid() function (otherwise it is unmodified).
**
** If the OPFLAG_USESEEKRESULT flag of P5 is set and if the result of
** the last seek operation (OP_NotExists) was a success, then this
** operation will not attempt to find the appropriate row before doing
** the insert but will instead overwrite the row that the cursor is
** currently pointing to.  Presumably, the prior OP_NotExists opcode
** has already positioned the cursor correctly.  This is an optimization
** that boosts performance by avoiding redundant seeks.
**
** If the OPFLAG_ISUPDATE flag is set, then this opcode is part of an
** UPDATE operation.  Otherwise (if the flag is clear) then this opcode
** is part of an INSERT operation.  The difference is only important to
** the update hook.
**
** Parameter P4 may point to a string containing the table-name, or
** may be NULL. If it is not NULL, then the update-hook 
** (sqlite3.xUpdateCallback) is invoked following a successful insert.
**
** (WARNING/TODO: If P1 is a pseudo-cursor and P2 is dynamically
** allocated, then ownership of P2 is transferred to the pseudo-cursor
** and register P2 becomes ephemeral.  If the cursor is changed, the
** value of register P2 will then change.  Make sure this does not
** cause any problems.)
**
** This instruction only works on tables.  The equivalent instruction
** for indices is OP_IdxInsert.
*/
case OP_Insert: {
  Mem *pData;       /* MEM cell holding data for the record to be inserted */
  Mem *pKey;        /* MEM cell holding key  for the record */
  i64 iKey;         /* The integer ROWID or key for the record to be inserted */
  VdbeCursor *pC;   /* Cursor to table into which insert is written */
  int nZero;        /* Number of zero-bytes to append */
  int seekResult;   /* Result of prior seek or 0 if no USESEEKRESULT flag */
  const char *zDb;  /* database name - used by the update hook */
  const char *zTbl; /* Table name - used by the opdate hook */
  int op;           /* Opcode for update hook: SQLITE_UPDATE or SQLITE_INSERT */

  pData = &p->aMem[pOp->p2];
  pKey = &p->aMem[pOp->p3];
  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  assert( pC->pCursor!=0 );
  assert( pC->pseudoTableReg==0 );
  assert( pKey->flags & MEM_Int );
  assert( pC->isTable );
  REGISTER_TRACE(pOp->p2, pData);
  REGISTER_TRACE(pOp->p3, pKey);

  iKey = pKey->u.i;
  if( pOp->p5 & OPFLAG_NCHANGE ) p->nChange++;
  if( pOp->p5 & OPFLAG_LASTROWID ) db->lastRowid = pKey->u.i;
  if( pData->flags & MEM_Null ){
    pData->z = 0;
    pData->n = 0;
  }else{
    assert( pData->flags & (MEM_Blob|MEM_Str) );
  }






















  seekResult = ((pOp->p5 & OPFLAG_USESEEKRESULT) ? pC->seekResult : 0);
  if( pData->flags & MEM_Zero ){
    nZero = pData->u.nZero;
  }else{
    nZero = 0;
  }
  sqlite3BtreeSetCachedRowid(pC->pCursor, 0);
  rc = sqlite3BtreeInsert(pC->pCursor, 0, iKey,
                          pData->z, pData->n, nZero,
                          pOp->p5 & OPFLAG_APPEND, seekResult
  );


  pC->rowidIsValid = 0;
  pC->deferredMoveto = 0;
  pC->cacheStatus = CACHE_STALE;

  /* Invoke the update-hook if required. */
  if( rc==SQLITE_OK && db->xUpdateCallback && pOp->p4.z ){
    zDb = db->aDb[pC->iDb].zName;

  /* Note that RowKey and RowData are really exactly the same instruction */
  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC->isTable || pOp->opcode==OP_RowKey );
  assert( pC->isIndex || pOp->opcode==OP_RowData );
  assert( pC!=0 );
  assert( pC->nullRow==0 );
  assert( pC->pseudoTableReg==0 );
  assert( pC->pCursor!=0 );
  pCrsr = pC->pCursor;
  assert( sqlite3BtreeCursorIsValid(pCrsr) );

  /* The OP_RowKey and OP_RowData opcodes always follow OP_NotExists or
  ** OP_Rewind/Op_Next with no intervening instructions that might invalidate
  ** the cursor.  Hence the following sqlite3VdbeCursorMoveto() call is always

  i64 v;
  sqlite3_vtab *pVtab;
  const sqlite3_module *pModule;

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  assert( pC->pseudoTableReg==0 );
  if( pC->nullRow ){
    /* Do nothing so that reg[P2] remains NULL */
    break;
  }else if( pC->deferredMoveto ){
    v = pC->movetoTarget;


#ifndef SQLITE_OMIT_VIRTUALTABLE
  }else if( pC->pVtabCursor ){
    pVtab = pC->pVtabCursor->pVtab;
    pModule = pVtab->pModule;
    assert( pModule->xRowid );
    if( sqlite3SafetyOff(db) ) goto abort_due_to_misuse;
    rc = pModule->xRowid(pC->pVtabCursor, &v);

  int iDb;              /* Index of cursor database in db->aDb[] (or -1) */
  i64 lastRowid;        /* Last rowid from a Next or NextIdx operation */
  Bool zeroed;          /* True if zeroed out and ready for reuse */
  Bool rowidIsValid;    /* True if lastRowid is valid */
  Bool atFirst;         /* True if pointing to first entry */
  Bool useRandomRowid;  /* Generate new record numbers semi-randomly */
  Bool nullRow;         /* True if pointing to a row with no data */


  Bool deferredMoveto;  /* A call to sqlite3BtreeMoveto() is needed */
  Bool isTable;         /* True if a table requiring integer keys */
  Bool isIndex;         /* True if an index containing keys only - no data */
  i64 movetoTarget;     /* Argument to the deferred sqlite3BtreeMoveto() */
  Btree *pBt;           /* Separate file holding temporary table */

  int pseudoTableReg;   /* Register holding pseudotable content. */

  KeyInfo *pKeyInfo;    /* Info about index keys needed by index cursors */
  int nField;           /* Number of fields in the header */
  i64 seqCount;         /* Sequence counter */
  sqlite3_vtab_cursor *pVtabCursor;  /* The cursor for a virtual table */
  const sqlite3_module *pModule;     /* Module for cursor pVtabCursor */

  /* Result of last sqlite3BtreeMoveto() done by an OP_NotExists or 
  ** OP_IsUnique opcode on this cursor. */
  int seekResult;

  /* Cached information about the header for the data record that the
  ** cursor is currently pointing to.  Only valid if cacheStatus matches
  ** Vdbe.cacheCtr.  Vdbe.cacheCtr will never take on the value of
  ** CACHE_STALE and so setting cacheStatus=CACHE_STALE guarantees that
  ** the cache is out of date.
  **
  ** aRow might point to (ephemeral) data for the current row, or it might
  ** be NULL.
  */
  u32 cacheStatus;      /* Cache is valid if this matches Vdbe.cacheCtr */
  int payloadSize;      /* Total number of bytes in the record */
  u32 *aType;           /* Type values for all entries in the record */
  u32 *aOffset;         /* Cached offsets to the start of each columns data */
  u8 *aRow;             /* Data for the current row, if all on one page */
};
typedef struct VdbeCursor VdbeCursor;

  u8 okVar;               /* True if azVar[] has been initialized */
  u16 nVar;               /* Number of entries in aVar[] */
  Mem *aVar;              /* Values for the OP_Variable opcode. */
  char **azVar;           /* Name of variables */
  u32 magic;              /* Magic number for sanity checking */
  int nMem;               /* Number of memory locations currently allocated */
  Mem *aMem;              /* The memory locations */
  u32 cacheCtr;           /* VdbeCursor row cache generation counter */
  int pc;                 /* The program counter */
  int rc;                 /* Value to return */
  char *zErrMsg;          /* Error message written here */
  u8 explain;             /* True if EXPLAIN present on SQL command */
  u8 changeCntOn;         /* True to update the change-counter */
  u8 expired;             /* True if the VM needs to be recompiled */
  u8 minWriteFileFormat;  /* Minimum file format for writable database files */

    p->inVtabMethod = 1;
    (void)sqlite3SafetyOff(p->db);
    pModule->xClose(pVtabCursor);
    (void)sqlite3SafetyOn(p->db);
    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
** control to the main program.
*/