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Overview
Comment:Remove the unused P5 flag from the OP_Rewind opcode.
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SHA3-256:c2edbf3b8c643edcd5823eb907fd7531cf5be8a8b6a014fa1b123eb0ea3231cf
User & Date: drh 2019-03-29 15:21:22
Context
2019-03-30
17:07
Add an extra IO-error test to windowfault.test. check-in: 5b8c44cd user: dan tags: trunk
2019-03-29
15:21
Remove the unused P5 flag from the OP_Rewind opcode. check-in: c2edbf3b user: drh tags: trunk
13:17
Fix a fairly obscure problem causing the planner to sometimes choose sub-optimal plans for a query with a single virtual table in the FROM clause, and at least one IN(...) constraint in the WHERE clause. check-in: f5752517 user: dan tags: trunk
Changes
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Changes to src/btree.c.

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    assert( pCur->pgnoRoot==0 || pCur->pPage->nCell==0 );
    *pRes = 1;
    rc = SQLITE_OK;
  }
  return rc;
}

/*
** This function is a no-op if cursor pCur does not point to a valid row.
** Otherwise, if pCur is valid, configure it so that the next call to
** sqlite3BtreeNext() is a no-op.
*/
#ifndef SQLITE_OMIT_WINDOWFUNC
void sqlite3BtreeSkipNext(BtCursor *pCur){
  /* We believe that the cursor must always be in the valid state when
  ** this routine is called, but the proof is difficult, so we add an
  ** ALWaYS() test just in case we are wrong. */
  if( ALWAYS(pCur->eState==CURSOR_VALID) ){
    pCur->eState = CURSOR_SKIPNEXT;
    pCur->skipNext = 1;
  }
}
#endif /* SQLITE_OMIT_WINDOWFUNC */

/* Move the cursor to the last entry in the table.  Return SQLITE_OK
** on success.  Set *pRes to 0 if the cursor actually points to something
** or set *pRes to 1 if the table is empty.
*/
int sqlite3BtreeLast(BtCursor *pCur, int *pRes){
  int rc;
 







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    assert( pCur->pgnoRoot==0 || pCur->pPage->nCell==0 );
    *pRes = 1;
    rc = SQLITE_OK;
  }
  return rc;
}


















/* Move the cursor to the last entry in the table.  Return SQLITE_OK
** on success.  Set *pRes to 0 if the cursor actually points to something
** or set *pRes to 1 if the table is empty.
*/
int sqlite3BtreeLast(BtCursor *pCur, int *pRes){
  int rc;
 

Changes to src/btree.h.

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  int nData;              /* Size of pData.  0 if none. */
  int nZero;              /* Extra zero data appended after pData,nData */
};

int sqlite3BtreeInsert(BtCursor*, const BtreePayload *pPayload,
                       int flags, int seekResult);
int sqlite3BtreeFirst(BtCursor*, int *pRes);
#ifndef SQLITE_OMIT_WINDOWFUNC
void sqlite3BtreeSkipNext(BtCursor*);
#endif
int sqlite3BtreeLast(BtCursor*, int *pRes);
int sqlite3BtreeNext(BtCursor*, int flags);
int sqlite3BtreeEof(BtCursor*);
int sqlite3BtreePrevious(BtCursor*, int flags);
i64 sqlite3BtreeIntegerKey(BtCursor*);
#ifdef SQLITE_ENABLE_OFFSET_SQL_FUNC
i64 sqlite3BtreeOffset(BtCursor*);







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  int nData;              /* Size of pData.  0 if none. */
  int nZero;              /* Extra zero data appended after pData,nData */
};

int sqlite3BtreeInsert(BtCursor*, const BtreePayload *pPayload,
                       int flags, int seekResult);
int sqlite3BtreeFirst(BtCursor*, int *pRes);



int sqlite3BtreeLast(BtCursor*, int *pRes);
int sqlite3BtreeNext(BtCursor*, int flags);
int sqlite3BtreeEof(BtCursor*);
int sqlite3BtreePrevious(BtCursor*, int flags);
i64 sqlite3BtreeIntegerKey(BtCursor*);
#ifdef SQLITE_ENABLE_OFFSET_SQL_FUNC
i64 sqlite3BtreeOffset(BtCursor*);

Changes to src/vdbe.c.

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#ifdef SQLITE_TEST
  sqlite3_sort_count++;
  sqlite3_search_count--;
#endif
  p->aCounter[SQLITE_STMTSTATUS_SORT]++;
  /* Fall through into OP_Rewind */
}
/* Opcode: Rewind P1 P2 * * P5
**
** 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, jump immediately to P2.
** If the table or index is not empty, fall through to the following 
** instruction.
**
** If P5 is non-zero and the table is not empty, then the "skip-next"
** flag is set on the cursor so that the next OP_Next instruction 
** executed on it is a no-op.
**
** This opcode leaves the cursor configured to move in forward order,
** from the beginning toward the end.  In other words, the cursor is
** configured to use Next, not 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(pC, &res);
  }else{
    assert( pC->eCurType==CURTYPE_BTREE );
    pCrsr = pC->uc.pCursor;
    assert( pCrsr );
    rc = sqlite3BtreeFirst(pCrsr, &res);
#ifndef SQLITE_OMIT_WINDOWFUNC
    if( pOp->p5 ) sqlite3BtreeSkipNext(pCrsr);
#endif
    pC->deferredMoveto = 0;
    pC->cacheStatus = CACHE_STALE;
  }
  if( rc ) goto abort_due_to_error;
  pC->nullRow = (u8)res;
  assert( pOp->p2>0 && pOp->p2<p->nOp );
  VdbeBranchTaken(res!=0,2);







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#ifdef SQLITE_TEST
  sqlite3_sort_count++;
  sqlite3_search_count--;
#endif
  p->aCounter[SQLITE_STMTSTATUS_SORT]++;
  /* Fall through into OP_Rewind */
}
/* 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, jump immediately to P2.
** 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 beginning toward the end.  In other words, the cursor is
** configured to use Next, not Prev.
*/
case OP_Rewind: {        /* jump */
  VdbeCursor *pC;
  BtCursor *pCrsr;
  int res;

  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  assert( pOp->p5==0 );
  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(pC, &res);
  }else{
    assert( pC->eCurType==CURTYPE_BTREE );
    pCrsr = pC->uc.pCursor;
    assert( pCrsr );
    rc = sqlite3BtreeFirst(pCrsr, &res);



    pC->deferredMoveto = 0;
    pC->cacheStatus = CACHE_STALE;
  }
  if( rc ) goto abort_due_to_error;
  pC->nullRow = (u8)res;
  assert( pOp->p2>0 && pOp->p2<p->nOp );
  VdbeBranchTaken(res!=0,2);