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Overview
Comment:Add constraints (enforced only when SQLITE_DEBUG is enabled) on the use of OP_Next and OP_Prev.
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SHA1: 2230c74f1efa591770176c9b40e920724a3c39e1
User & Date: drh 2014-07-25 18:01:06.435
Context
2014-07-25
18:37
Improved comments on VDBE opcodes, for better documentation. No code or logic changes. (check-in: 2d32e4876e user: drh tags: trunk)
18:01
Add constraints (enforced only when SQLITE_DEBUG is enabled) on the use of OP_Next and OP_Prev. (check-in: 2230c74f1e user: drh tags: trunk)
2014-07-24
23:23
Improve the performance of the ANALYZE command by taking advantage of UNIQUE constraints on indices. (check-in: 114dcf3367 user: drh tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/vdbe.c.
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case OP_Close: {
  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  sqlite3VdbeFreeCursor(p, p->apCsr[pOp->p1]);
  p->apCsr[pOp->p1] = 0;
  break;
}

/* Opcode: SeekGe P1 P2 P3 P4 *
** Synopsis: key=r[P3@P4]
**
** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
** use the value in register P3 as the key.  If cursor P1 refers 
** to an SQL index, then P3 is the first in an array of P4 registers 
** that are used as an unpacked index key. 
**
** Reposition cursor P1 so that  it points to the smallest entry that 
** is greater than or equal to the key value. If there are no records 
** greater than or equal to the key and P2 is not zero, then jump to P2.




**
** See also: Found, NotFound, SeekLt, SeekGt, SeekLe
*/
/* Opcode: SeekGt P1 P2 P3 P4 *
** Synopsis: key=r[P3@P4]
**
** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
** use the value in register P3 as a key. If cursor P1 refers 
** to an SQL index, then P3 is the first in an array of P4 registers 
** that are used as an unpacked index key. 
**
** Reposition cursor P1 so that  it points to the smallest entry that 
** is greater than the key value. If there are no records greater than 
** the key and P2 is not zero, then jump to P2.




**
** See also: Found, NotFound, SeekLt, SeekGe, SeekLe
*/
/* Opcode: SeekLt P1 P2 P3 P4 * 
** Synopsis: key=r[P3@P4]
**
** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
** use the value in register P3 as a key. If cursor P1 refers 
** to an SQL index, then P3 is the first in an array of P4 registers 
** that are used as an unpacked index key. 
**
** Reposition cursor P1 so that  it points to the largest entry that 
** is less than the key value. If there are no records less than 
** the key and P2 is not zero, then jump to P2.




**
** See also: Found, NotFound, SeekGt, SeekGe, SeekLe
*/
/* Opcode: SeekLe P1 P2 P3 P4 *
** Synopsis: key=r[P3@P4]
**
** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
** use the value in register P3 as a key. If cursor P1 refers 
** to an SQL index, then P3 is the first in an array of P4 registers 
** that are used as an unpacked index key. 
**
** Reposition cursor P1 so that it points to the largest entry that 
** is less than or equal to the key value. If there are no records 
** less than or equal to the key and P2 is not zero, then jump to P2.




**
** See also: Found, NotFound, SeekGt, SeekGe, SeekLt
*/
case OP_SeekLT:         /* jump, in3 */
case OP_SeekLE:         /* jump, in3 */
case OP_SeekGE:         /* jump, in3 */
case OP_SeekGT: {       /* jump, in3 */







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case OP_Close: {
  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  sqlite3VdbeFreeCursor(p, p->apCsr[pOp->p1]);
  p->apCsr[pOp->p1] = 0;
  break;
}

/* Opcode: SeekGE P1 P2 P3 P4 *
** Synopsis: key=r[P3@P4]
**
** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
** use the value in register P3 as the key.  If cursor P1 refers 
** to an SQL index, then P3 is the first in an array of P4 registers 
** that are used as an unpacked index key. 
**
** Reposition cursor P1 so that  it points to the smallest entry that 
** is greater than or equal to the key value. If there are no records 
** greater than or equal to the key and P2 is not zero, then jump to P2.
**
** This opcode leaves the cursor configured to move in forward order,
** from the begining toward the end.  In other words, the cursor is
** configured to use OP_Next, not OP_Prev.
**
** See also: Found, NotFound, SeekLt, SeekGt, SeekLe
*/
/* Opcode: SeekGT P1 P2 P3 P4 *
** Synopsis: key=r[P3@P4]
**
** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
** use the value in register P3 as a key. If cursor P1 refers 
** to an SQL index, then P3 is the first in an array of P4 registers 
** that are used as an unpacked index key. 
**
** Reposition cursor P1 so that  it points to the smallest entry that 
** is greater than the key value. If there are no records greater than 
** the key and P2 is not zero, then jump to P2.
**
** This opcode leaves the cursor configured to move in forward order,
** from the begining toward the end.  In other words, the cursor is
** configured to use OP_Next, not OP_Prev.
**
** See also: Found, NotFound, SeekLt, SeekGe, SeekLe
*/
/* Opcode: SeekLT P1 P2 P3 P4 * 
** Synopsis: key=r[P3@P4]
**
** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
** use the value in register P3 as a key. If cursor P1 refers 
** to an SQL index, then P3 is the first in an array of P4 registers 
** that are used as an unpacked index key. 
**
** Reposition cursor P1 so that  it points to the largest entry that 
** is less than the key value. If there are no records less than 
** the key and P2 is not zero, then jump to P2.
**
** This opcode leaves the cursor configured to move in reverse order,
** from the end toward the beginning.  In other words, the cursor is
** configured to use OP_Prev, not OP_Next.
**
** See also: Found, NotFound, SeekGt, SeekGe, SeekLe
*/
/* Opcode: SeekLE P1 P2 P3 P4 *
** Synopsis: key=r[P3@P4]
**
** If cursor P1 refers to an SQL table (B-Tree that uses integer keys), 
** use the value in register P3 as a key. If cursor P1 refers 
** to an SQL index, then P3 is the first in an array of P4 registers 
** that are used as an unpacked index key. 
**
** Reposition cursor P1 so that it points to the largest entry that 
** is less than or equal to the key value. If there are no records 
** less than or equal to the key and P2 is not zero, then jump to P2.
**
** This opcode leaves the cursor configured to move in reverse order,
** from the end toward the beginning.  In other words, the cursor is
** configured to use OP_Prev, not OP_Next.
**
** See also: Found, NotFound, SeekGt, SeekGe, SeekLt
*/
case OP_SeekLT:         /* jump, in3 */
case OP_SeekLE:         /* jump, in3 */
case OP_SeekGE:         /* jump, in3 */
case OP_SeekGT: {       /* jump, in3 */
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  assert( OP_SeekLE == OP_SeekLT+1 );
  assert( OP_SeekGE == OP_SeekLT+2 );
  assert( OP_SeekGT == OP_SeekLT+3 );
  assert( pC->isOrdered );
  assert( 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. */
    pIn3 = &aMem[pOp->p3];
    applyNumericAffinity(pIn3);
    iKey = sqlite3VdbeIntValue(pIn3);







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  assert( OP_SeekLE == OP_SeekLT+1 );
  assert( OP_SeekGE == OP_SeekLT+2 );
  assert( OP_SeekGT == OP_SeekLT+3 );
  assert( pC->isOrdered );
  assert( pC->pCursor!=0 );
  oc = pOp->opcode;
  pC->nullRow = 0;
#ifdef SQLITE_DEBUG
  pC->seekOp = pOp->opcode;
#endif
  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. */
    pIn3 = &aMem[pOp->p3];
    applyNumericAffinity(pIn3);
    iKey = sqlite3VdbeIntValue(pIn3);
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** If P4==0 then register P3 holds a blob constructed by MakeRecord.  If
** P4>0 then register P3 is the first of P4 registers that form an unpacked
** record.
**
** Cursor P1 is on an index btree.  If the record identified by P3 and P4
** is a prefix of any entry in P1 then a jump is made to P2 and
** P1 is left pointing at the matching entry.




**
** See also: NotFound, NoConflict, NotExists. SeekGe
*/
/* Opcode: NotFound P1 P2 P3 P4 *
** Synopsis: key=r[P3@P4]
**
** If P4==0 then register P3 holds a blob constructed by MakeRecord.  If
** P4>0 then register P3 is the first of P4 registers that form an unpacked
** record.
** 
** Cursor P1 is on an index btree.  If the record identified by P3 and P4
** is not the prefix of any entry in P1 then a jump is made to P2.  If P1 
** does contain an entry whose prefix matches the P3/P4 record then control
** falls through to the next instruction and P1 is left pointing at the
** matching entry.




**
** See also: Found, NotExists, NoConflict
*/
/* Opcode: NoConflict P1 P2 P3 P4 *
** Synopsis: key=r[P3@P4]
**
** If P4==0 then register P3 holds a blob constructed by MakeRecord.  If
** P4>0 then register P3 is the first of P4 registers that form an unpacked
** record.
** 
** Cursor P1 is on an index btree.  If the record identified by P3 and P4
** contains any NULL value, jump immediately to P2.  If all terms of the
** record are not-NULL then a check is done to determine if any row in the
** P1 index btree has a matching key prefix.  If there are no matches, jump
** immediately to P2.  If there is a match, fall through and leave the P1
** cursor pointing to the matching row.
**
** This opcode is similar to OP_NotFound with the exceptions that the
** branch is always taken if any part of the search key input is NULL.




**
** See also: NotFound, Found, NotExists
*/
case OP_NoConflict:     /* jump, in3 */
case OP_NotFound:       /* jump, in3 */
case OP_Found: {        /* jump, in3 */
  int alreadyExists;







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** If P4==0 then register P3 holds a blob constructed by MakeRecord.  If
** P4>0 then register P3 is the first of P4 registers that form an unpacked
** record.
**
** Cursor P1 is on an index btree.  If the record identified by P3 and P4
** is a prefix of any entry in P1 then a jump is made to P2 and
** P1 is left pointing at the matching entry.
**
** This operation leaves the cursor in a state where it cannot be
** advanced in either direction.  In other words, the Next and Prev
** opcodes do not work after this operation.
**
** See also: NotFound, NoConflict, NotExists. SeekGe
*/
/* Opcode: NotFound P1 P2 P3 P4 *
** Synopsis: key=r[P3@P4]
**
** If P4==0 then register P3 holds a blob constructed by MakeRecord.  If
** P4>0 then register P3 is the first of P4 registers that form an unpacked
** record.
** 
** Cursor P1 is on an index btree.  If the record identified by P3 and P4
** is not the prefix of any entry in P1 then a jump is made to P2.  If P1 
** does contain an entry whose prefix matches the P3/P4 record then control
** falls through to the next instruction and P1 is left pointing at the
** matching entry.
**
** This operation leaves the cursor in a state where it cannot be
** advanced in either direction.  In other words, the Next and Prev
** opcodes do not work after this operation.
**
** See also: Found, NotExists, NoConflict
*/
/* Opcode: NoConflict P1 P2 P3 P4 *
** Synopsis: key=r[P3@P4]
**
** If P4==0 then register P3 holds a blob constructed by MakeRecord.  If
** P4>0 then register P3 is the first of P4 registers that form an unpacked
** record.
** 
** Cursor P1 is on an index btree.  If the record identified by P3 and P4
** contains any NULL value, jump immediately to P2.  If all terms of the
** record are not-NULL then a check is done to determine if any row in the
** P1 index btree has a matching key prefix.  If there are no matches, jump
** immediately to P2.  If there is a match, fall through and leave the P1
** cursor pointing to the matching row.
**
** This opcode is similar to OP_NotFound with the exceptions that the
** branch is always taken if any part of the search key input is NULL.
**
** This operation leaves the cursor in a state where it cannot be
** advanced in either direction.  In other words, the Next and Prev
** opcodes do not work after this operation.
**
** See also: NotFound, Found, NotExists
*/
case OP_NoConflict:     /* jump, in3 */
case OP_NotFound:       /* jump, in3 */
case OP_Found: {        /* jump, in3 */
  int alreadyExists;
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  if( pOp->opcode!=OP_NoConflict ) sqlite3_found_count++;
#endif

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  assert( pOp->p4type==P4_INT32 );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );



  pIn3 = &aMem[pOp->p3];
  assert( pC->pCursor!=0 );
  assert( pC->isTable==0 );
  pFree = 0;  /* Not needed.  Only used to suppress a compiler warning. */
  if( pOp->p4.i>0 ){
    r.pKeyInfo = pC->pKeyInfo;
    r.nField = (u16)pOp->p4.i;







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  if( pOp->opcode!=OP_NoConflict ) sqlite3_found_count++;
#endif

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  assert( pOp->p4type==P4_INT32 );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
#ifdef SQLITE_DEBUG
  pC->seekOp = 0;
#endif
  pIn3 = &aMem[pOp->p3];
  assert( pC->pCursor!=0 );
  assert( pC->isTable==0 );
  pFree = 0;  /* Not needed.  Only used to suppress a compiler warning. */
  if( pOp->p4.i>0 ){
    r.pKeyInfo = pC->pKeyInfo;
    r.nField = (u16)pOp->p4.i;
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** keys).  P3 is an integer rowid.  If P1 does not contain a record with
** rowid P3 then jump immediately to P2.  If P1 does contain a record
** with rowid P3 then leave the cursor pointing at that record and fall
** through to the next instruction.
**
** The OP_NotFound opcode performs the same operation on index btrees
** (with arbitrary multi-value keys).




**
** See also: Found, NotFound, NoConflict
*/
case OP_NotExists: {        /* jump, in3 */
  VdbeCursor *pC;
  BtCursor *pCrsr;
  int res;
  u64 iKey;

  pIn3 = &aMem[pOp->p3];
  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;
  assert( pCrsr!=0 );
  res = 0;
  iKey = pIn3->u.i;
  rc = sqlite3BtreeMovetoUnpacked(pCrsr, 0, iKey, 0, &res);







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** keys).  P3 is an integer rowid.  If P1 does not contain a record with
** rowid P3 then jump immediately to P2.  If P1 does contain a record
** with rowid P3 then leave the cursor pointing at that record and fall
** through to the next instruction.
**
** The OP_NotFound opcode performs the same operation on index btrees
** (with arbitrary multi-value keys).
**
** This opcode leaves the cursor in a state where it cannot be advanced
** in either direction.  In other words, the Next and Prev opcodes will
** not work following this opcode.
**
** See also: Found, NotFound, NoConflict
*/
case OP_NotExists: {        /* jump, in3 */
  VdbeCursor *pC;
  BtCursor *pCrsr;
  int res;
  u64 iKey;

  pIn3 = &aMem[pOp->p3];
  assert( pIn3->flags & MEM_Int );
  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
#ifdef SQLITE_DEBUG
  pC->seekOp = 0;
#endif
  assert( pC->isTable );
  assert( pC->pseudoTableReg==0 );
  pCrsr = pC->pCursor;
  assert( pCrsr!=0 );
  res = 0;
  iKey = pIn3->u.i;
  rc = sqlite3BtreeMovetoUnpacked(pCrsr, 0, iKey, 0, &res);
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    sqlite3BtreeClearCursor(pC->pCursor);
  }
  break;
}

/* Opcode: Last P1 P2 * * *
**
** The next use of the Rowid or Column or Next instruction for P1 
** will refer to the last entry in the database table or index.
** If the table or index is empty and P2>0, then jump immediately to P2.
** If P2 is 0 or if the table or index is not empty, fall through
** to the following instruction.




*/
case OP_Last: {        /* jump */
  VdbeCursor *pC;
  BtCursor *pCrsr;
  int res;

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  pCrsr = pC->pCursor;
  res = 0;
  assert( pCrsr!=0 );
  rc = sqlite3BtreeLast(pCrsr, &res);
  pC->nullRow = (u8)res;
  pC->deferredMoveto = 0;
  pC->rowidIsValid = 0;
  pC->cacheStatus = CACHE_STALE;



  if( pOp->p2>0 ){
    VdbeBranchTaken(res!=0,2);
    if( res ) pc = pOp->p2 - 1;
  }
  break;
}








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    sqlite3BtreeClearCursor(pC->pCursor);
  }
  break;
}

/* Opcode: Last P1 P2 * * *
**
** The next use of the Rowid or Column or Prev instruction for P1 
** will refer to the last entry in the database table or index.
** If the table or index is empty and P2>0, then jump immediately to P2.
** If P2 is 0 or if the table or index is not empty, fall through
** to the following instruction.
**
** This opcode leaves the cursor configured to move in reverse order,
** from the end toward the beginning.  In other words, the cursor is
** configured to use OP_Prev, not OP_Next.
*/
case OP_Last: {        /* jump */
  VdbeCursor *pC;
  BtCursor *pCrsr;
  int res;

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  pCrsr = pC->pCursor;
  res = 0;
  assert( pCrsr!=0 );
  rc = sqlite3BtreeLast(pCrsr, &res);
  pC->nullRow = (u8)res;
  pC->deferredMoveto = 0;
  pC->rowidIsValid = 0;
  pC->cacheStatus = CACHE_STALE;
#ifdef SQLITE_DEBUG
  pC->seekOp = OP_Last;
#endif
  if( pOp->p2>0 ){
    VdbeBranchTaken(res!=0,2);
    if( res ) pc = pOp->p2 - 1;
  }
  break;
}

4475
4476
4477
4478
4479
4480
4481




4482
4483
4484
4485
4486
4487
4488
4489
4490
4491
4492



4493
4494
4495
4496
4497
4498
4499
/* Opcode: Rewind P1 P2 * * *
**
** The next use of the Rowid or Column or Next instruction for P1 
** will refer to the first entry in the database table or index.
** If the table or index is empty and P2>0, then jump immediately to P2.
** If P2 is 0 or if the table or index is not empty, fall through
** to the following instruction.




*/
case OP_Rewind: {        /* jump */
  VdbeCursor *pC;
  BtCursor *pCrsr;
  int res;

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  assert( isSorter(pC)==(pOp->opcode==OP_SorterSort) );
  res = 1;



  if( isSorter(pC) ){
    rc = sqlite3VdbeSorterRewind(db, pC, &res);
  }else{
    pCrsr = pC->pCursor;
    assert( pCrsr );
    rc = sqlite3BtreeFirst(pCrsr, &res);
    pC->deferredMoveto = 0;







>
>
>
>











>
>
>







4523
4524
4525
4526
4527
4528
4529
4530
4531
4532
4533
4534
4535
4536
4537
4538
4539
4540
4541
4542
4543
4544
4545
4546
4547
4548
4549
4550
4551
4552
4553
4554
/* Opcode: Rewind P1 P2 * * *
**
** The next use of the Rowid or Column or Next instruction for P1 
** will refer to the first entry in the database table or index.
** If the table or index is empty and P2>0, then jump immediately to P2.
** If P2 is 0 or if the table or index is not empty, fall through
** to the following instruction.
**
** This opcode leaves the cursor configured to move in forward order,
** from the begining toward the end.  In other words, the cursor is
** configured to use OP_Next, not OP_Prev.
*/
case OP_Rewind: {        /* jump */
  VdbeCursor *pC;
  BtCursor *pCrsr;
  int res;

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  assert( isSorter(pC)==(pOp->opcode==OP_SorterSort) );
  res = 1;
#ifdef SQLITE_DEBUG
  pC->seekOp = OP_Rewind;
#endif
  if( isSorter(pC) ){
    rc = sqlite3VdbeSorterRewind(db, pC, &res);
  }else{
    pCrsr = pC->pCursor;
    assert( pCrsr );
    rc = sqlite3BtreeFirst(pCrsr, &res);
    pC->deferredMoveto = 0;
4511
4512
4513
4514
4515
4516
4517




4518
4519
4520
4521
4522
4523
4524

/* Opcode: Next P1 P2 P3 P4 P5
**
** Advance cursor P1 so that it points to the next key/data pair in its
** table or index.  If there are no more key/value pairs then fall through
** to the following instruction.  But if the cursor advance was successful,
** jump immediately to P2.




**
** The P1 cursor must be for a real table, not a pseudo-table.  P1 must have
** been opened prior to this opcode or the program will segfault.
**
** The P3 value is a hint to the btree implementation. If P3==1, that
** means P1 is an SQL index and that this instruction could have been
** omitted if that index had been unique.  P3 is usually 0.  P3 is







>
>
>
>







4566
4567
4568
4569
4570
4571
4572
4573
4574
4575
4576
4577
4578
4579
4580
4581
4582
4583

/* Opcode: Next P1 P2 P3 P4 P5
**
** Advance cursor P1 so that it points to the next key/data pair in its
** table or index.  If there are no more key/value pairs then fall through
** to the following instruction.  But if the cursor advance was successful,
** jump immediately to P2.
**
** The OP_Next opcode is only valid following an OP_SeekGT, OP_SeekGE, or
** OP_Rewind opcode used to position the cursor.  OP_Next is not allowed
** to follow OP_SeekLT, OP_SeekLE, or OP_Last.
**
** The P1 cursor must be for a real table, not a pseudo-table.  P1 must have
** been opened prior to this opcode or the program will segfault.
**
** The P3 value is a hint to the btree implementation. If P3==1, that
** means P1 is an SQL index and that this instruction could have been
** omitted if that index had been unique.  P3 is usually 0.  P3 is
4540
4541
4542
4543
4544
4545
4546





4547
4548
4549
4550
4551
4552
4553
/* Opcode: Prev P1 P2 P3 P4 P5
**
** Back up cursor P1 so that it points to the previous key/data pair in its
** table or index.  If there is no previous key/value pairs then fall through
** to the following instruction.  But if the cursor backup was successful,
** jump immediately to P2.
**





** The P1 cursor must be for a real table, not a pseudo-table.  If P1 is
** not open then the behavior is undefined.
**
** The P3 value is a hint to the btree implementation. If P3==1, that
** means P1 is an SQL index and that this instruction could have been
** omitted if that index had been unique.  P3 is usually 0.  P3 is
** always either 0 or 1.







>
>
>
>
>







4599
4600
4601
4602
4603
4604
4605
4606
4607
4608
4609
4610
4611
4612
4613
4614
4615
4616
4617
/* Opcode: Prev P1 P2 P3 P4 P5
**
** Back up cursor P1 so that it points to the previous key/data pair in its
** table or index.  If there is no previous key/value pairs then fall through
** to the following instruction.  But if the cursor backup was successful,
** jump immediately to P2.
**
**
** The OP_Prev opcode is only valid following an OP_SeekLT, OP_SeekLE, or
** OP_Last opcode used to position the cursor.  OP_Prev is not allowed
** to follow OP_SeekGT, OP_SeekGE, or OP_Rewind.
**
** The P1 cursor must be for a real table, not a pseudo-table.  If P1 is
** not open then the behavior is undefined.
**
** The P3 value is a hint to the btree implementation. If P3==1, that
** means P1 is an SQL index and that this instruction could have been
** omitted if that index had been unique.  P3 is usually 0.  P3 is
** always either 0 or 1.
4587
4588
4589
4590
4591
4592
4593










4594
4595
4596
4597
4598
4599
4600
  assert( pC->pCursor );
  assert( res==0 || (res==1 && pC->isTable==0) );
  testcase( res==1 );
  assert( pOp->opcode!=OP_Next || pOp->p4.xAdvance==sqlite3BtreeNext );
  assert( pOp->opcode!=OP_Prev || pOp->p4.xAdvance==sqlite3BtreePrevious );
  assert( pOp->opcode!=OP_NextIfOpen || pOp->p4.xAdvance==sqlite3BtreeNext );
  assert( pOp->opcode!=OP_PrevIfOpen || pOp->p4.xAdvance==sqlite3BtreePrevious);










  rc = pOp->p4.xAdvance(pC->pCursor, &res);
next_tail:
  pC->cacheStatus = CACHE_STALE;
  VdbeBranchTaken(res==0,2);
  if( res==0 ){
    pC->nullRow = 0;
    pc = pOp->p2 - 1;







>
>
>
>
>
>
>
>
>
>







4651
4652
4653
4654
4655
4656
4657
4658
4659
4660
4661
4662
4663
4664
4665
4666
4667
4668
4669
4670
4671
4672
4673
4674
  assert( pC->pCursor );
  assert( res==0 || (res==1 && pC->isTable==0) );
  testcase( res==1 );
  assert( pOp->opcode!=OP_Next || pOp->p4.xAdvance==sqlite3BtreeNext );
  assert( pOp->opcode!=OP_Prev || pOp->p4.xAdvance==sqlite3BtreePrevious );
  assert( pOp->opcode!=OP_NextIfOpen || pOp->p4.xAdvance==sqlite3BtreeNext );
  assert( pOp->opcode!=OP_PrevIfOpen || pOp->p4.xAdvance==sqlite3BtreePrevious);

  /* The Next opcode is only used after SeekGT, SeekGE, and Rewind.
  ** The Prev opcode is only used after SeekLT, SeekLE, and Last. */
  assert( pOp->opcode!=OP_Next || pOp->opcode!=OP_NextIfOpen
       || pC->seekOp==OP_SeekGT || pC->seekOp==OP_SeekGE
       || pC->seekOp==OP_Rewind );
  assert( pOp->opcode!=OP_Prev || pOp->opcode!=OP_PrevIfOpen
       || pC->seekOp==OP_SeekLT || pC->seekOp==OP_SeekLE
       || pC->seekOp==OP_Last );

  rc = pOp->p4.xAdvance(pC->pCursor, &res);
next_tail:
  pC->cacheStatus = CACHE_STALE;
  VdbeBranchTaken(res==0,2);
  if( res==0 ){
    pC->nullRow = 0;
    pc = pOp->p2 - 1;
Changes to src/vdbeInt.h.
64
65
66
67
68
69
70



71
72
73
74
75
76
77
  BtCursor *pCursor;    /* The cursor structure of the backend */
  Btree *pBt;           /* Separate file holding temporary table */
  KeyInfo *pKeyInfo;    /* Info about index keys needed by index cursors */
  int seekResult;       /* Result of previous sqlite3BtreeMoveto() */
  int pseudoTableReg;   /* Register holding pseudotable content. */
  i16 nField;           /* Number of fields in the header */
  u16 nHdrParsed;       /* Number of header fields parsed so far */



  i8 iDb;               /* Index of cursor database in db->aDb[] (or -1) */
  u8 nullRow;           /* True if pointing to a row with no data */
  u8 rowidIsValid;      /* True if lastRowid is valid */
  u8 deferredMoveto;    /* A call to sqlite3BtreeMoveto() is needed */
  Bool isEphemeral:1;   /* True for an ephemeral table */
  Bool useRandomRowid:1;/* Generate new record numbers semi-randomly */
  Bool isTable:1;       /* True if a table requiring integer keys */







>
>
>







64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
  BtCursor *pCursor;    /* The cursor structure of the backend */
  Btree *pBt;           /* Separate file holding temporary table */
  KeyInfo *pKeyInfo;    /* Info about index keys needed by index cursors */
  int seekResult;       /* Result of previous sqlite3BtreeMoveto() */
  int pseudoTableReg;   /* Register holding pseudotable content. */
  i16 nField;           /* Number of fields in the header */
  u16 nHdrParsed;       /* Number of header fields parsed so far */
#ifdef SQLITE_DEBUG
  u8 seekOp;            /* Most recent seek operation on this cursor */
#endif
  i8 iDb;               /* Index of cursor database in db->aDb[] (or -1) */
  u8 nullRow;           /* True if pointing to a row with no data */
  u8 rowidIsValid;      /* True if lastRowid is valid */
  u8 deferredMoveto;    /* A call to sqlite3BtreeMoveto() is needed */
  Bool isEphemeral:1;   /* True for an ephemeral table */
  Bool useRandomRowid:1;/* Generate new record numbers semi-randomly */
  Bool isTable:1;       /* True if a table requiring integer keys */