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Comment:Attempt to speed up sqlite3VdbeRecordCompare() by various means. This code is in an interim state.
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SHA1:85206e0bbac29adab52bef795f6d1479f2ae2c0e
User & Date: dan 2014-02-25 21:01:25
Context
2014-02-27
20:44
Further changes to sqlite3VdbeRecordCompare(). check-in: 57089374 user: dan tags: experimental
2014-02-25
21:01
Attempt to speed up sqlite3VdbeRecordCompare() by various means. This code is in an interim state. check-in: 85206e0b user: dan tags: experimental
18:12
Also adjust the order of files in the amalgamation to ensure that _FILE_OFFSET_BITS is defined before any #include, for QNX. check-in: 23001a85 user: drh tags: trunk
Changes
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Changes to src/btree.c.

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  BtCursor *pCur,          /* The cursor to be moved */
  UnpackedRecord *pIdxKey, /* Unpacked index key */
  i64 intKey,              /* The table key */
  int biasRight,           /* If true, bias the search to the high end */
  int *pRes                /* Write search results here */
){
  int rc;


  assert( cursorHoldsMutex(pCur) );
  assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
  assert( pRes );
  assert( (pIdxKey==0)==(pCur->pKeyInfo==0) );

  /* If the cursor is already positioned at the point we are trying
................................................................................
      return SQLITE_OK;
    }
    if( pCur->atLast && pCur->info.nKey<intKey ){
      *pRes = -1;
      return SQLITE_OK;
    }
  }






  rc = moveToRoot(pCur);
  if( rc ){
    return rc;
  }
  assert( pCur->pgnoRoot==0 || pCur->apPage[pCur->iPage] );
  assert( pCur->pgnoRoot==0 || pCur->apPage[pCur->iPage]->isInit );
................................................................................
        */
        nCell = pCell[0];
        if( nCell<=pPage->max1bytePayload ){
          /* This branch runs if the record-size field of the cell is a
          ** single byte varint and the record fits entirely on the main
          ** b-tree page.  */
          testcase( pCell+nCell+1==pPage->aDataEnd );
          c = sqlite3VdbeRecordCompare(nCell, (void*)&pCell[1], pIdxKey);
        }else if( !(pCell[1] & 0x80) 
          && (nCell = ((nCell&0x7f)<<7) + pCell[1])<=pPage->maxLocal
        ){
          /* The record-size field is a 2 byte varint and the record 
          ** fits entirely on the main b-tree page.  */
          testcase( pCell+nCell+2==pPage->aDataEnd );
          c = sqlite3VdbeRecordCompare(nCell, (void*)&pCell[2], pIdxKey);
        }else{
          /* The record flows over onto one or more overflow pages. In
          ** this case the whole cell needs to be parsed, a buffer allocated
          ** and accessPayload() used to retrieve the record into the
          ** buffer before VdbeRecordCompare() can be called. */
          void *pCellKey;
          u8 * const pCellBody = pCell - pPage->childPtrSize;
................................................................................
          }
          pCur->aiIdx[pCur->iPage] = (u16)idx;
          rc = accessPayload(pCur, 0, nCell, (unsigned char*)pCellKey, 0);
          if( rc ){
            sqlite3_free(pCellKey);
            goto moveto_finish;
          }
          c = sqlite3VdbeRecordCompare(nCell, pCellKey, pIdxKey);
          sqlite3_free(pCellKey);
        }
        if( c<0 ){
          lwr = idx+1;
        }else if( c>0 ){
          upr = idx-1;
        }else{







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  BtCursor *pCur,          /* The cursor to be moved */
  UnpackedRecord *pIdxKey, /* Unpacked index key */
  i64 intKey,              /* The table key */
  int biasRight,           /* If true, bias the search to the high end */
  int *pRes                /* Write search results here */
){
  int rc;
  int (*xRecordCompare)(int, const void*, UnpackedRecord*);

  assert( cursorHoldsMutex(pCur) );
  assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
  assert( pRes );
  assert( (pIdxKey==0)==(pCur->pKeyInfo==0) );

  /* If the cursor is already positioned at the point we are trying
................................................................................
      return SQLITE_OK;
    }
    if( pCur->atLast && pCur->info.nKey<intKey ){
      *pRes = -1;
      return SQLITE_OK;
    }
  }

  if( pIdxKey ){
    xRecordCompare = sqlite3VdbeFindCompare(pIdxKey);
    assert( pIdxKey->default_rc==1 || pIdxKey->default_rc==0 || pIdxKey->default_rc==-1);
  }

  rc = moveToRoot(pCur);
  if( rc ){
    return rc;
  }
  assert( pCur->pgnoRoot==0 || pCur->apPage[pCur->iPage] );
  assert( pCur->pgnoRoot==0 || pCur->apPage[pCur->iPage]->isInit );
................................................................................
        */
        nCell = pCell[0];
        if( nCell<=pPage->max1bytePayload ){
          /* This branch runs if the record-size field of the cell is a
          ** single byte varint and the record fits entirely on the main
          ** b-tree page.  */
          testcase( pCell+nCell+1==pPage->aDataEnd );
          c = xRecordCompare(nCell, (void*)&pCell[1], pIdxKey);
        }else if( !(pCell[1] & 0x80) 
          && (nCell = ((nCell&0x7f)<<7) + pCell[1])<=pPage->maxLocal
        ){
          /* The record-size field is a 2 byte varint and the record 
          ** fits entirely on the main b-tree page.  */
          testcase( pCell+nCell+2==pPage->aDataEnd );
          c = xRecordCompare(nCell, (void*)&pCell[2], pIdxKey);
        }else{
          /* The record flows over onto one or more overflow pages. In
          ** this case the whole cell needs to be parsed, a buffer allocated
          ** and accessPayload() used to retrieve the record into the
          ** buffer before VdbeRecordCompare() can be called. */
          void *pCellKey;
          u8 * const pCellBody = pCell - pPage->childPtrSize;
................................................................................
          }
          pCur->aiIdx[pCur->iPage] = (u16)idx;
          rc = accessPayload(pCur, 0, nCell, (unsigned char*)pCellKey, 0);
          if( rc ){
            sqlite3_free(pCellKey);
            goto moveto_finish;
          }
          c = xRecordCompare(nCell, pCellKey, pIdxKey);
          sqlite3_free(pCellKey);
        }
        if( c<0 ){
          lwr = idx+1;
        }else if( c>0 ){
          upr = idx-1;
        }else{

Changes to src/sqliteInt.h.

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**
** This structure holds a record that has already been disassembled
** into its constituent fields.
*/
struct UnpackedRecord {
  KeyInfo *pKeyInfo;  /* Collation and sort-order information */
  u16 nField;         /* Number of entries in apMem[] */
  u8 flags;           /* Boolean settings.  UNPACKED_... below */
  Mem *aMem;          /* Values */
};

/*
** Allowed values of UnpackedRecord.flags
*/
#define UNPACKED_INCRKEY       0x01  /* Make this key an epsilon larger */
#define UNPACKED_PREFIX_MATCH  0x02  /* A prefix match is considered OK */

/*
** Each SQL index is represented in memory by an
** instance of the following structure.
**
** The columns of the table that are to be indexed are described
** by the aiColumn[] field of this structure.  For example, suppose







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**
** This structure holds a record that has already been disassembled
** into its constituent fields.
*/
struct UnpackedRecord {
  KeyInfo *pKeyInfo;  /* Collation and sort-order information */
  u16 nField;         /* Number of entries in apMem[] */
  char default_rc;    /* Comparison result if keys are equal */
  Mem *aMem;          /* Values */
};







/*
** Each SQL index is represented in memory by an
** instance of the following structure.
**
** The columns of the table that are to be indexed are described
** by the aiColumn[] field of this structure.  For example, suppose

Changes to src/vdbe.c.

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    assert( pOp->p4type==P4_INT32 );
    assert( nField>0 );
    r.pKeyInfo = pC->pKeyInfo;
    r.nField = (u16)nField;

    /* The next line of code computes as follows, only faster:
    **   if( oc==OP_SeekGT || oc==OP_SeekLE ){
    **     r.flags = UNPACKED_INCRKEY;
    **   }else{
    **     r.flags = 0;
    **   }
    */
    r.flags = (u8)(UNPACKED_INCRKEY * (1 & (oc - OP_SeekLT)));
    assert( oc!=OP_SeekGT || r.flags==UNPACKED_INCRKEY );
    assert( oc!=OP_SeekLE || r.flags==UNPACKED_INCRKEY );
    assert( oc!=OP_SeekGE || r.flags==0 );
    assert( oc!=OP_SeekLT || r.flags==0 );

    r.aMem = &aMem[pOp->p3];
#ifdef SQLITE_DEBUG
    { int i; for(i=0; i<r.nField; i++) assert( memIsValid(&r.aMem[i]) ); }
#endif
    ExpandBlob(r.aMem);
    rc = sqlite3BtreeMovetoUnpacked(pC->pCursor, &r, 0, 0, &res);
................................................................................
    for(ii=0; ii<r.nField; ii++){
      assert( memIsValid(&r.aMem[ii]) );
      ExpandBlob(&r.aMem[ii]);
#ifdef SQLITE_DEBUG
      if( ii ) REGISTER_TRACE(pOp->p3+ii, &r.aMem[ii]);
#endif
    }
    r.flags = UNPACKED_PREFIX_MATCH;
    pIdxKey = &r;
  }else{
    pIdxKey = sqlite3VdbeAllocUnpackedRecord(
        pC->pKeyInfo, aTempRec, sizeof(aTempRec), &pFree
    ); 
    if( pIdxKey==0 ) goto no_mem;
    assert( pIn3->flags & MEM_Blob );
    assert( (pIn3->flags & MEM_Zero)==0 );  /* zeroblobs already expanded */
    sqlite3VdbeRecordUnpack(pC->pKeyInfo, pIn3->n, pIn3->z, pIdxKey);
    pIdxKey->flags |= UNPACKED_PREFIX_MATCH;
  }

  if( pOp->opcode==OP_NoConflict ){
    /* For the OP_NoConflict opcode, take the jump if any of the
    ** input fields are NULL, since any key with a NULL will not
    ** conflict */
    for(ii=0; ii<r.nField; ii++){
      if( r.aMem[ii].flags & MEM_Null ){
        pc = pOp->p2 - 1; VdbeBranchTaken(1,2);
................................................................................
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  pCrsr = pC->pCursor;
  assert( pCrsr!=0 );
  assert( pOp->p5==0 );
  r.pKeyInfo = pC->pKeyInfo;
  r.nField = (u16)pOp->p3;
  r.flags = UNPACKED_PREFIX_MATCH;
  r.aMem = &aMem[pOp->p2];
#ifdef SQLITE_DEBUG
  { int i; for(i=0; i<r.nField; i++) assert( memIsValid(&r.aMem[i]) ); }
#endif
  rc = sqlite3BtreeMovetoUnpacked(pCrsr, &r, 0, 0, &res);
  if( rc==SQLITE_OK && res==0 ){
    rc = sqlite3BtreeDelete(pCrsr);
................................................................................
  assert( pC->deferredMoveto==0 );
  assert( pOp->p5==0 || pOp->p5==1 );
  assert( pOp->p4type==P4_INT32 );
  r.pKeyInfo = pC->pKeyInfo;
  r.nField = (u16)pOp->p4.i;
  if( pOp->opcode<OP_IdxLT ){
    assert( pOp->opcode==OP_IdxLE || pOp->opcode==OP_IdxGT );
    r.flags = UNPACKED_INCRKEY | UNPACKED_PREFIX_MATCH;
  }else{
    assert( pOp->opcode==OP_IdxGE || pOp->opcode==OP_IdxLT );
    r.flags = UNPACKED_PREFIX_MATCH;
  }
  r.aMem = &aMem[pOp->p3];
#ifdef SQLITE_DEBUG
  { int i; for(i=0; i<r.nField; i++) assert( memIsValid(&r.aMem[i]) ); }
#endif
  res = 0;  /* Not needed.  Only used to silence a warning. */
  rc = sqlite3VdbeIdxKeyCompare(pC, &r, &res);







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    assert( pOp->p4type==P4_INT32 );
    assert( nField>0 );
    r.pKeyInfo = pC->pKeyInfo;
    r.nField = (u16)nField;

    /* The next line of code computes as follows, only faster:
    **   if( oc==OP_SeekGT || oc==OP_SeekLE ){
    **     r.default_rc = -1;
    **   }else{
    **     r.default_rc = +1;
    **   }
    */
    r.default_rc = ((1 & (oc - OP_SeekLT)) ? -1 : +1);
    assert( oc!=OP_SeekGT || r.default_rc==-1 );
    assert( oc!=OP_SeekLE || r.default_rc==-1 );
    assert( oc!=OP_SeekGE || r.default_rc==+1 );
    assert( oc!=OP_SeekLT || r.default_rc==+1 );

    r.aMem = &aMem[pOp->p3];
#ifdef SQLITE_DEBUG
    { int i; for(i=0; i<r.nField; i++) assert( memIsValid(&r.aMem[i]) ); }
#endif
    ExpandBlob(r.aMem);
    rc = sqlite3BtreeMovetoUnpacked(pC->pCursor, &r, 0, 0, &res);
................................................................................
    for(ii=0; ii<r.nField; ii++){
      assert( memIsValid(&r.aMem[ii]) );
      ExpandBlob(&r.aMem[ii]);
#ifdef SQLITE_DEBUG
      if( ii ) REGISTER_TRACE(pOp->p3+ii, &r.aMem[ii]);
#endif
    }

    pIdxKey = &r;
  }else{
    pIdxKey = sqlite3VdbeAllocUnpackedRecord(
        pC->pKeyInfo, aTempRec, sizeof(aTempRec), &pFree
    ); 
    if( pIdxKey==0 ) goto no_mem;
    assert( pIn3->flags & MEM_Blob );
    assert( (pIn3->flags & MEM_Zero)==0 );  /* zeroblobs already expanded */
    sqlite3VdbeRecordUnpack(pC->pKeyInfo, pIn3->n, pIn3->z, pIdxKey);

  }
  pIdxKey->default_rc = 0;
  if( pOp->opcode==OP_NoConflict ){
    /* For the OP_NoConflict opcode, take the jump if any of the
    ** input fields are NULL, since any key with a NULL will not
    ** conflict */
    for(ii=0; ii<r.nField; ii++){
      if( r.aMem[ii].flags & MEM_Null ){
        pc = pOp->p2 - 1; VdbeBranchTaken(1,2);
................................................................................
  pC = p->apCsr[pOp->p1];
  assert( pC!=0 );
  pCrsr = pC->pCursor;
  assert( pCrsr!=0 );
  assert( pOp->p5==0 );
  r.pKeyInfo = pC->pKeyInfo;
  r.nField = (u16)pOp->p3;
  r.default_rc = 0;
  r.aMem = &aMem[pOp->p2];
#ifdef SQLITE_DEBUG
  { int i; for(i=0; i<r.nField; i++) assert( memIsValid(&r.aMem[i]) ); }
#endif
  rc = sqlite3BtreeMovetoUnpacked(pCrsr, &r, 0, 0, &res);
  if( rc==SQLITE_OK && res==0 ){
    rc = sqlite3BtreeDelete(pCrsr);
................................................................................
  assert( pC->deferredMoveto==0 );
  assert( pOp->p5==0 || pOp->p5==1 );
  assert( pOp->p4type==P4_INT32 );
  r.pKeyInfo = pC->pKeyInfo;
  r.nField = (u16)pOp->p4.i;
  if( pOp->opcode<OP_IdxLT ){
    assert( pOp->opcode==OP_IdxLE || pOp->opcode==OP_IdxGT );
    r.default_rc = -1;
  }else{
    assert( pOp->opcode==OP_IdxGE || pOp->opcode==OP_IdxLT );
    r.default_rc = 0;
  }
  r.aMem = &aMem[pOp->p3];
#ifdef SQLITE_DEBUG
  { int i; for(i=0; i<r.nField; i++) assert( memIsValid(&r.aMem[i]) ); }
#endif
  res = 0;  /* Not needed.  Only used to silence a warning. */
  rc = sqlite3VdbeIdxKeyCompare(pC, &r, &res);

Changes to src/vdbe.h.

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#ifndef SQLITE_OMIT_TRACE
  char *sqlite3VdbeExpandSql(Vdbe*, const char*);
#endif

void sqlite3VdbeRecordUnpack(KeyInfo*,int,const void*,UnpackedRecord*);
int sqlite3VdbeRecordCompare(int,const void*,UnpackedRecord*);
UnpackedRecord *sqlite3VdbeAllocUnpackedRecord(KeyInfo *, char *, int, char **);




#ifndef SQLITE_OMIT_TRIGGER
void sqlite3VdbeLinkSubProgram(Vdbe *, SubProgram *);
#endif

/* Use SQLITE_ENABLE_COMMENTS to enable generation of extra comments on
** each VDBE opcode.







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#ifndef SQLITE_OMIT_TRACE
  char *sqlite3VdbeExpandSql(Vdbe*, const char*);
#endif

void sqlite3VdbeRecordUnpack(KeyInfo*,int,const void*,UnpackedRecord*);
int sqlite3VdbeRecordCompare(int,const void*,UnpackedRecord*);
UnpackedRecord *sqlite3VdbeAllocUnpackedRecord(KeyInfo *, char *, int, char **);

typedef int (*RecordCompare)(int,const void*, UnpackedRecord*);
RecordCompare sqlite3VdbeFindCompare(UnpackedRecord *);

#ifndef SQLITE_OMIT_TRIGGER
void sqlite3VdbeLinkSubProgram(Vdbe *, SubProgram *);
#endif

/* Use SQLITE_ENABLE_COMMENTS to enable generation of extra comments on
** each VDBE opcode.

Changes to src/vdbeaux.c.

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  const unsigned char *aKey = (const unsigned char *)pKey;
  int d; 
  u32 idx;                        /* Offset in aKey[] to read from */
  u16 u;                          /* Unsigned loop counter */
  u32 szHdr;
  Mem *pMem = p->aMem;

  p->flags = 0;
  assert( EIGHT_BYTE_ALIGNMENT(pMem) );
  idx = getVarint32(aKey, szHdr);
  d = szHdr;
  u = 0;
  while( idx<szHdr && u<p->nField && d<=nKey ){
    u32 serial_type;

................................................................................
    d += sqlite3VdbeSerialGet(&aKey[d], serial_type, pMem);
    pMem++;
    u++;
  }
  assert( u<=pKeyInfo->nField + 1 );
  p->nField = u;
}


















































































































































































































/*
** This function compares the two table rows or index records
** specified by {nKey1, pKey1} and pPKey2.  It returns a negative, zero
** or positive integer if key1 is less than, equal to or 
** greater than key2.  The {nKey1, pKey1} key must be a blob
** created by th OP_MakeRecord opcode of the VDBE.  The pPKey2
................................................................................
** The key with fewer fields is usually compares less than the 
** longer key.  However if the UNPACKED_INCRKEY flags in pPKey2 is set
** and the common prefixes are equal, then key1 is less than key2.
** Or if the UNPACKED_MATCH_PREFIX flag is set and the prefixes are
** equal, then the keys are considered to be equal and
** the parts beyond the common prefix are ignored.
*/
int sqlite3VdbeRecordCompare(
  int nKey1, const void *pKey1, /* Left key */
  UnpackedRecord *pPKey2        /* Right key */
){
  u32 d1;            /* Offset into aKey[] of next data element */
  u32 idx1;          /* Offset into aKey[] of next header element */
  u32 szHdr1;        /* Number of bytes in header */
  int i = 0;
................................................................................
  /* No memory allocation is ever used on mem1.  Prove this using
  ** the following assert().  If the assert() fails, it indicates a
  ** memory leak and a need to call sqlite3VdbeMemRelease(&mem1).
  */
  assert( mem1.zMalloc==0 );

  /* rc==0 here means that one of the keys ran out of fields and
  ** all the fields up to that point were equal. If the UNPACKED_INCRKEY
  ** flag is set, then break the tie by treating key2 as larger.
  ** If the UPACKED_PREFIX_MATCH flag is set, then keys with common prefixes
  ** are considered to be equal.  Otherwise, the longer key is the 
  ** larger.  As it happens, the pPKey2 will always be the longer
  ** if there is a difference.
  */




  assert( rc==0 );
  if( pPKey2->flags & UNPACKED_INCRKEY ){



































    rc = -1;
  }else if( pPKey2->flags & UNPACKED_PREFIX_MATCH ){
    /* Leave rc==0 */






































  }else if( idx1<szHdr1 ){
    rc = 1;
  }
































































  return rc;
}
 

































/*
** pCur points at an index entry created using the OP_MakeRecord opcode.
** Read the rowid (the last field in the record) and store it in *rowid.
** Return SQLITE_OK if everything works, or an error code otherwise.
**
** pCur might be pointing to text obtained from a corrupt database file.
................................................................................
    return SQLITE_CORRUPT_BKPT;
  }
  memset(&m, 0, sizeof(m));
  rc = sqlite3VdbeMemFromBtree(pC->pCursor, 0, (u32)nCellKey, 1, &m);
  if( rc ){
    return rc;
  }
  assert( pUnpacked->flags & UNPACKED_PREFIX_MATCH );
  *res = sqlite3VdbeRecordCompare(m.n, m.z, pUnpacked);
  sqlite3VdbeMemRelease(&m);
  return SQLITE_OK;
}

/*
** This routine sets the value to be returned by subsequent calls to







|







 







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  const unsigned char *aKey = (const unsigned char *)pKey;
  int d; 
  u32 idx;                        /* Offset in aKey[] to read from */
  u16 u;                          /* Unsigned loop counter */
  u32 szHdr;
  Mem *pMem = p->aMem;

  p->default_rc = 0;
  assert( EIGHT_BYTE_ALIGNMENT(pMem) );
  idx = getVarint32(aKey, szHdr);
  d = szHdr;
  u = 0;
  while( idx<szHdr && u<p->nField && d<=nKey ){
    u32 serial_type;

................................................................................
    d += sqlite3VdbeSerialGet(&aKey[d], serial_type, pMem);
    pMem++;
    u++;
  }
  assert( u<=pKeyInfo->nField + 1 );
  p->nField = u;
}

static int vdbeRecordCompareString(
  int nKey1, const void *pKey1, /* Left key */
  UnpackedRecord *pPKey2        /* Right key */
){
  const u8 *aKey1 = (const u8*)pKey1;
  int szHdr;
  int serial_type;
  int res;

  szHdr = aKey1[0];
  getVarint32(&aKey1[1], serial_type);

  if( serial_type<12 ){
    res = -1;      /* (pKey1/nKey1) is a number or a null */
  }else if( !(serial_type & 0x01) ){ 
    res = +1;      /* (pKey1/nKey1) is a blob */
  }else{
    int nCmp;
    int nStr;
    aKey1 = &aKey1[szHdr];

    nStr = (serial_type-12) / 2;
    if( (szHdr + nStr) > nKey1 ) return 0;    /* Corruption */
    nCmp = MIN( pPKey2->aMem[0].n, nStr );
    res = memcmp(aKey1, pPKey2->aMem[0].z, nCmp);

    if( res==0 ){
      res = nStr - pPKey2->aMem[0].n;
      if( res==0 ) res = pPKey2->default_rc;
    }
  }

  assert( (res==0 && sqlite3VdbeRecordCompare(nKey1, pKey1, pPKey2)==0)
       || (res<0 && sqlite3VdbeRecordCompare(nKey1, pKey1, pPKey2)<0)
       || (res>0 && sqlite3VdbeRecordCompare(nKey1, pKey1, pPKey2)>0)
  );
  return res;
}

static int vdbeRecordCompareInt(
  int nKey1, const void *pKey1, /* Left key */
  UnpackedRecord *pPKey2        /* Right key */
){
  const u8 *aKey1 = (const u8*)pKey1;
  int szHdr;
  int serial_type;
  int res;

  szHdr = aKey1[0];
  getVarint32(&aKey1[1], serial_type);

  if( serial_type==0 ){
    res = -1;      /* NULL values are smaller than integers */
  }else if( serial_type>=12 ){
    res = +1;      /* text/blob values are greater */
  }else{
    Mem mem;
    sqlite3VdbeSerialGet(&aKey1[szHdr], serial_type, &mem);
    if( mem.flags & MEM_Int ){
      i64 v = pPKey2->aMem[0].u.i;
      if( v>mem.u.i ){
        res = -1;
      }else if( v<mem.u.i ){
        res = +1;
      }else{
        res = pPKey2->default_rc;
      }
    }else{
      double v = (double)pPKey2->aMem[0].u.i;
      if( v>mem.r ){
        res = -1;
      }else if( v<mem.r ){
        res = +1;
      }else{
        res = pPKey2->default_rc;
      }
    }
  }

  assert( (res==0 && sqlite3VdbeRecordCompare(nKey1, pKey1, pPKey2)==0)
       || (res<0 && sqlite3VdbeRecordCompare(nKey1, pKey1, pPKey2)<0)
       || (res>0 && sqlite3VdbeRecordCompare(nKey1, pKey1, pPKey2)>0)
  );
  return res;
}

static int vdbeCompareMemString(
  const Mem *pMem1, 
  const Mem *pMem2, 
  const CollSeq *pColl
){
  if( pMem1->enc==pColl->enc ){
    /* The strings are already in the correct encoding.  Call the
     ** comparison function directly */
    return pColl->xCmp(pColl->pUser,pMem1->n,pMem1->z,pMem2->n,pMem2->z);
  }else{
    int rc;
    const void *v1, *v2;
    int n1, n2;
    Mem c1;
    Mem c2;
    memset(&c1, 0, sizeof(c1));
    memset(&c2, 0, sizeof(c2));
    sqlite3VdbeMemShallowCopy(&c1, pMem1, MEM_Ephem);
    sqlite3VdbeMemShallowCopy(&c2, pMem2, MEM_Ephem);
    v1 = sqlite3ValueText((sqlite3_value*)&c1, pColl->enc);
    n1 = v1==0 ? 0 : c1.n;
    v2 = sqlite3ValueText((sqlite3_value*)&c2, pColl->enc);
    n2 = v2==0 ? 0 : c2.n;
    rc = pColl->xCmp(pColl->pUser, n1, v1, n2, v2);
    sqlite3VdbeMemRelease(&c1);
    sqlite3VdbeMemRelease(&c2);
    return rc;
  }
}

/*
** Compare the values contained by the two memory cells, returning
** negative, zero or positive if pMem1 is less than, equal to, or greater
** than pMem2. Sorting order is NULL's first, followed by numbers (integers
** and reals) sorted numerically, followed by text ordered by the collating
** sequence pColl and finally blob's ordered by memcmp().
**
** Two NULL values are considered equal by this function.
*/
int sqlite3MemCompare(const Mem *pMem1, const Mem *pMem2, const CollSeq *pColl){
  int rc;
  int f1, f2;
  int combined_flags;

  f1 = pMem1->flags;
  f2 = pMem2->flags;
  combined_flags = f1|f2;
  assert( (combined_flags & MEM_RowSet)==0 );
 
  /* If one value is NULL, it is less than the other. If both values
  ** are NULL, return 0.
  */
  if( combined_flags&MEM_Null ){
    return (f2&MEM_Null) - (f1&MEM_Null);
  }

  /* If one value is a number and the other is not, the number is less.
  ** If both are numbers, compare as reals if one is a real, or as integers
  ** if both values are integers.
  */
  if( combined_flags&(MEM_Int|MEM_Real) ){
    double r1, r2;
    if( (f1 & f2 & MEM_Int)!=0 ){
      if( pMem1->u.i < pMem2->u.i ) return -1;
      if( pMem1->u.i > pMem2->u.i ) return 1;
      return 0;
    }
    if( (f1&MEM_Real)!=0 ){
      r1 = pMem1->r;
    }else if( (f1&MEM_Int)!=0 ){
      r1 = (double)pMem1->u.i;
    }else{
      return 1;
    }
    if( (f2&MEM_Real)!=0 ){
      r2 = pMem2->r;
    }else if( (f2&MEM_Int)!=0 ){
      r2 = (double)pMem2->u.i;
    }else{
      return -1;
    }
    if( r1<r2 ) return -1;
    if( r1>r2 ) return 1;
    return 0;
  }

  /* If one value is a string and the other is a blob, the string is less.
  ** If both are strings, compare using the collating functions.
  */
  if( combined_flags&MEM_Str ){
    if( (f1 & MEM_Str)==0 ){
      return 1;
    }
    if( (f2 & MEM_Str)==0 ){
      return -1;
    }

    assert( pMem1->enc==pMem2->enc );
    assert( pMem1->enc==SQLITE_UTF8 || 
            pMem1->enc==SQLITE_UTF16LE || pMem1->enc==SQLITE_UTF16BE );

    /* The collation sequence must be defined at this point, even if
    ** the user deletes the collation sequence after the vdbe program is
    ** compiled (this was not always the case).
    */
    assert( !pColl || pColl->xCmp );

    if( pColl ){
      return vdbeCompareMemString(pMem1, pMem2, pColl);
    }
    /* If a NULL pointer was passed as the collate function, fall through
    ** to the blob case and use memcmp().  */
  }
 
  /* Both values must be blobs.  Compare using memcmp().  */
  rc = memcmp(pMem1->z, pMem2->z, (pMem1->n>pMem2->n)?pMem2->n:pMem1->n);
  if( rc==0 ){
    rc = pMem1->n - pMem2->n;
  }
  return rc;
}


/*
** This function compares the two table rows or index records
** specified by {nKey1, pKey1} and pPKey2.  It returns a negative, zero
** or positive integer if key1 is less than, equal to or 
** greater than key2.  The {nKey1, pKey1} key must be a blob
** created by th OP_MakeRecord opcode of the VDBE.  The pPKey2
................................................................................
** The key with fewer fields is usually compares less than the 
** longer key.  However if the UNPACKED_INCRKEY flags in pPKey2 is set
** and the common prefixes are equal, then key1 is less than key2.
** Or if the UNPACKED_MATCH_PREFIX flag is set and the prefixes are
** equal, then the keys are considered to be equal and
** the parts beyond the common prefix are ignored.
*/
static int vdbeRecordComparePrev(
  int nKey1, const void *pKey1, /* Left key */
  UnpackedRecord *pPKey2        /* Right key */
){
  u32 d1;            /* Offset into aKey[] of next data element */
  u32 idx1;          /* Offset into aKey[] of next header element */
  u32 szHdr1;        /* Number of bytes in header */
  int i = 0;
................................................................................
  /* No memory allocation is ever used on mem1.  Prove this using
  ** the following assert().  If the assert() fails, it indicates a
  ** memory leak and a need to call sqlite3VdbeMemRelease(&mem1).
  */
  assert( mem1.zMalloc==0 );

  /* rc==0 here means that one of the keys ran out of fields and
  ** all the fields up to that point were equal. Return the the default_rc
  ** value.  */
  return pPKey2->default_rc;




}
 

int sqlite3VdbeRecordCompare(
  int nKey1, const void *pKey1, /* Left key */
  UnpackedRecord *pPKey2        /* Right key */
){
  u32 d1;            /* Offset into aKey[] of next data element */
  u32 idx1;          /* Offset into aKey[] of next header element */
  u32 szHdr1;        /* Number of bytes in header */
  int i = 0;
  int rc = 0;
  KeyInfo *pKeyInfo = pPKey2->pKeyInfo;
  const unsigned char *aKey1 = (const unsigned char *)pKey1;
  Mem mem1;

#ifdef SQLITE_DEBUG
  int expected = vdbeRecordComparePrev(nKey1, pKey1, pPKey2);
  static int nCall = 0;
  nCall++;
#endif

  VVA_ONLY( mem1.zMalloc = 0; ) /* Only needed by assert() statements */
  
  idx1 = getVarint32(aKey1, szHdr1);
  d1 = szHdr1;
  assert( pPKey2->pKeyInfo->nField+pPKey2->pKeyInfo->nXField>=pPKey2->nField 
       || CORRUPT_DB );
  assert( pPKey2->pKeyInfo->aSortOrder!=0 );
  assert( pPKey2->pKeyInfo->nField>0 );
  assert( idx1<=szHdr1 || CORRUPT_DB );
  do{
    Mem *pRhs = &pPKey2->aMem[i];
    u32 serial_type;

    /* RHS is an integer */
    if( pRhs->flags & MEM_Int ){
      serial_type = aKey1[idx1];
      if( serial_type>=12 ){
        rc = +1;
      }else if( serial_type==0 ){
        rc = -1;


      }else{
        sqlite3VdbeSerialGet(&aKey1[d1], serial_type, &mem1);
        if( serial_type==7 ){
          double rhs = (double)pRhs->u.i;
          if( mem1.r<rhs ){
            rc = -1;
          }else if( mem1.r>rhs ){
            rc = +1;
          }
        }else{
          i64 rhs = pRhs->u.i;
          if( mem1.u.i<rhs ){
            rc = -1;
          }else if( mem1.u.i>rhs ){
            rc = +1;
          }
        }
      }
    }

    /* RHS is real */
    else if( pRhs->flags & MEM_Real ){
      serial_type = aKey1[idx1];
      if( serial_type>=12 ){
        rc = +1;
      }else if( serial_type==0 ){
        rc = -1;
      }else{
        double rhs = pRhs->r;
        double lhs;
        sqlite3VdbeSerialGet(&aKey1[d1], serial_type, &mem1);
        if( serial_type==7 ){
          lhs = mem1.r;
        }else{
          lhs = mem1.u.i;
        }
        if( lhs<rhs ){
          rc = -1;
        }else if( lhs>rhs ){
          rc = +1;
        }
      }
    }

    /* RHS is a string */
    else if( pRhs->flags & MEM_Str ){
      getVarint32(&aKey1[idx1], serial_type);
      if( serial_type<12 ){
        rc = -1;
      }else if( !(serial_type & 0x01) ){
        rc = +1;
      }else{
        mem1.n = (serial_type - 12) / 2;
        if( (d1+mem1.n) > nKey1 ){
          rc = 1;                /* Corruption */
        }else if( pKeyInfo->aColl[i] ){
          mem1.enc = pKeyInfo->enc;
          mem1.db = pKeyInfo->db;
          mem1.flags = MEM_Str;
          mem1.z = &aKey1[d1];
          rc = vdbeCompareMemString(&mem1, pRhs, pKeyInfo->aColl[i]);
        }else{
          int nCmp = MIN(mem1.n, pRhs->n);
          rc = memcmp(&aKey1[d1], pRhs->z, nCmp);
          if( rc==0 ) rc = mem1.n - pRhs->n; 
        }
      }
    }

    /* RHS is a blob */
    else if( pRhs->flags & MEM_Blob ){
      getVarint32(&aKey1[idx1], serial_type);
      if( serial_type<12 || (serial_type & 0x01) ){
        rc = -1;
      }else{
        int nStr = (serial_type - 12) / 2;
        if( (d1+nStr) > nKey1 ){
          rc = 1;                /* Corruption */
        }else{
          int nCmp = MIN(nStr, pRhs->n);
          rc = memcmp(&aKey1[d1], pRhs->z, nCmp);
          if( rc==0 ) rc = nStr - pRhs->n;
        }
      }
    }

    /* RHS is null */
    else{
      serial_type = aKey1[idx1];
      rc = (serial_type!=0);
    }

    if( rc!=0 ){
      assert( mem1.zMalloc==0 );  /* See comment below */
      if( pKeyInfo->aSortOrder[i] ){
        rc = -rc;
#if 0
        assert( (rc>0 && (rc^(int)0x80000000)<0) 
             || (rc<0 && (rc^(int)0x80000000)>0) );
        assert( sizeof(int)==4 );
        rc ^= (int)0x80000000;    /* similar in spirit to: "rc = -rc;" */
        assert( rc!=0 );
#endif
      }
      assert( (rc<0 && expected<0) || (rc>0 && expected>0) || CORRUPT_DB );
      return rc;
    }

    i++;
    d1 += sqlite3VdbeSerialTypeLen(serial_type);
    idx1 += sqlite3VarintLen(serial_type);
  }while( idx1<szHdr1 && i<pPKey2->nField && d1<=nKey1 );

  /* No memory allocation is ever used on mem1.  Prove this using
  ** the following assert().  If the assert() fails, it indicates a
  ** memory leak and a need to call sqlite3VdbeMemRelease(&mem1).
  */
  assert( mem1.zMalloc==0 );

  /* rc==0 here means that one or both of the keys ran out of fields and
  ** all the fields up to that point were equal. Return the the default_rc
  ** value.  */
  assert( pPKey2->default_rc==expected );
  return pPKey2->default_rc;
}

RecordCompare sqlite3VdbeFindCompare(UnpackedRecord *p){
  if( p->nField==1 && p->pKeyInfo->aSortOrder[0]==0 ){
    int flags = p->aMem[0].flags;
    if( (flags & MEM_Int) ){
      return vdbeRecordCompareInt;
    }else if( (p->aMem[0].flags&(MEM_Int|MEM_Real|MEM_Null|MEM_Blob))==0 
            && p->pKeyInfo->aColl[0]==0 
    ){
      return vdbeRecordCompareString;
    }
  }
  return sqlite3VdbeRecordCompare;
}


/*
** pCur points at an index entry created using the OP_MakeRecord opcode.
** Read the rowid (the last field in the record) and store it in *rowid.
** Return SQLITE_OK if everything works, or an error code otherwise.
**
** pCur might be pointing to text obtained from a corrupt database file.
................................................................................
    return SQLITE_CORRUPT_BKPT;
  }
  memset(&m, 0, sizeof(m));
  rc = sqlite3VdbeMemFromBtree(pC->pCursor, 0, (u32)nCellKey, 1, &m);
  if( rc ){
    return rc;
  }

  *res = sqlite3VdbeRecordCompare(m.n, m.z, pUnpacked);
  sqlite3VdbeMemRelease(&m);
  return SQLITE_OK;
}

/*
** This routine sets the value to be returned by subsequent calls to

Changes to src/vdbemem.c.

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  if( nByte>iLimit ){
    return SQLITE_TOOBIG;
  }

  return SQLITE_OK;
}

/*
** Compare the values contained by the two memory cells, returning
** negative, zero or positive if pMem1 is less than, equal to, or greater
** than pMem2. Sorting order is NULL's first, followed by numbers (integers
** and reals) sorted numerically, followed by text ordered by the collating
** sequence pColl and finally blob's ordered by memcmp().
**
** Two NULL values are considered equal by this function.
*/
int sqlite3MemCompare(const Mem *pMem1, const Mem *pMem2, const CollSeq *pColl){
  int rc;
  int f1, f2;
  int combined_flags;

  f1 = pMem1->flags;
  f2 = pMem2->flags;
  combined_flags = f1|f2;
  assert( (combined_flags & MEM_RowSet)==0 );
 
  /* If one value is NULL, it is less than the other. If both values
  ** are NULL, return 0.
  */
  if( combined_flags&MEM_Null ){
    return (f2&MEM_Null) - (f1&MEM_Null);
  }

  /* If one value is a number and the other is not, the number is less.
  ** If both are numbers, compare as reals if one is a real, or as integers
  ** if both values are integers.
  */
  if( combined_flags&(MEM_Int|MEM_Real) ){
    double r1, r2;
    if( (f1 & f2 & MEM_Int)!=0 ){
      if( pMem1->u.i < pMem2->u.i ) return -1;
      if( pMem1->u.i > pMem2->u.i ) return 1;
      return 0;
    }
    if( (f1&MEM_Real)!=0 ){
      r1 = pMem1->r;
    }else if( (f1&MEM_Int)!=0 ){
      r1 = (double)pMem1->u.i;
    }else{
      return 1;
    }
    if( (f2&MEM_Real)!=0 ){
      r2 = pMem2->r;
    }else if( (f2&MEM_Int)!=0 ){
      r2 = (double)pMem2->u.i;
    }else{
      return -1;
    }
    if( r1<r2 ) return -1;
    if( r1>r2 ) return 1;
    return 0;
  }

  /* If one value is a string and the other is a blob, the string is less.
  ** If both are strings, compare using the collating functions.
  */
  if( combined_flags&MEM_Str ){
    if( (f1 & MEM_Str)==0 ){
      return 1;
    }
    if( (f2 & MEM_Str)==0 ){
      return -1;
    }

    assert( pMem1->enc==pMem2->enc );
    assert( pMem1->enc==SQLITE_UTF8 || 
            pMem1->enc==SQLITE_UTF16LE || pMem1->enc==SQLITE_UTF16BE );

    /* The collation sequence must be defined at this point, even if
    ** the user deletes the collation sequence after the vdbe program is
    ** compiled (this was not always the case).
    */
    assert( !pColl || pColl->xCmp );

    if( pColl ){
      if( pMem1->enc==pColl->enc ){
        /* The strings are already in the correct encoding.  Call the
        ** comparison function directly */
        return pColl->xCmp(pColl->pUser,pMem1->n,pMem1->z,pMem2->n,pMem2->z);
      }else{
        const void *v1, *v2;
        int n1, n2;
        Mem c1;
        Mem c2;
        memset(&c1, 0, sizeof(c1));
        memset(&c2, 0, sizeof(c2));
        sqlite3VdbeMemShallowCopy(&c1, pMem1, MEM_Ephem);
        sqlite3VdbeMemShallowCopy(&c2, pMem2, MEM_Ephem);
        v1 = sqlite3ValueText((sqlite3_value*)&c1, pColl->enc);
        n1 = v1==0 ? 0 : c1.n;
        v2 = sqlite3ValueText((sqlite3_value*)&c2, pColl->enc);
        n2 = v2==0 ? 0 : c2.n;
        rc = pColl->xCmp(pColl->pUser, n1, v1, n2, v2);
        sqlite3VdbeMemRelease(&c1);
        sqlite3VdbeMemRelease(&c2);
        return rc;
      }
    }
    /* If a NULL pointer was passed as the collate function, fall through
    ** to the blob case and use memcmp().  */
  }
 
  /* Both values must be blobs.  Compare using memcmp().  */
  rc = memcmp(pMem1->z, pMem2->z, (pMem1->n>pMem2->n)?pMem2->n:pMem1->n);
  if( rc==0 ){
    rc = pMem1->n - pMem2->n;
  }
  return rc;
}

/*
** Move data out of a btree key or data field and into a Mem structure.
** The data or key is taken from the entry that pCur is currently pointing
** to.  offset and amt determine what portion of the data or key to retrieve.
** key is true to get the key or false to get data.  The result is written
** into the pMem element.
**







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  if( nByte>iLimit ){
    return SQLITE_TOOBIG;
  }

  return SQLITE_OK;
}


















































































































/*
** Move data out of a btree key or data field and into a Mem structure.
** The data or key is taken from the entry that pCur is currently pointing
** to.  offset and amt determine what portion of the data or key to retrieve.
** key is true to get the key or false to get data.  The result is written
** into the pMem element.
**

Changes to src/vdbesort.c.

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    assert( r2->nField>0 );
    for(i=0; i<r2->nField; i++){
      if( r2->aMem[i].flags & MEM_Null ){
        *pRes = -1;
        return;
      }
    }
    r2->flags |= UNPACKED_PREFIX_MATCH;
  }

  *pRes = sqlite3VdbeRecordCompare(nKey1, pKey1, r2);
}

/*
** This function is called to compare two iterator keys when merging 







|







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    assert( r2->nField>0 );
    for(i=0; i<r2->nField; i++){
      if( r2->aMem[i].flags & MEM_Null ){
        *pRes = -1;
        return;
      }
    }
    assert( r2->default_rc==0 );
  }

  *pRes = sqlite3VdbeRecordCompare(nKey1, pKey1, r2);
}

/*
** This function is called to compare two iterator keys when merging 

Changes to test/pragma.test.

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do_test pragma-20.8 {
  catchsql {PRAGMA data_store_directory}
} {0 {}}

forcedelete data_dir
} ;# endif windows



do_test 21.1 {
  # Create a corrupt database in testerr.db. And a non-corrupt at test.db.
  #
  db close
  forcedelete test.db
  sqlite3 db test.db
  execsql { 
................................................................................
    CREATE TABLE t2(x, y INTEGER REFERENCES t1);
  }
  db2 eval {
    PRAGMA foreign_key_list(t2);
  }
} {0 0 t1 y {} {NO ACTION} {NO ACTION} NONE}


finish_test







>
>







 







>

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do_test pragma-20.8 {
  catchsql {PRAGMA data_store_directory}
} {0 {}}

forcedelete data_dir
} ;# endif windows

database_may_be_corrupt

do_test 21.1 {
  # Create a corrupt database in testerr.db. And a non-corrupt at test.db.
  #
  db close
  forcedelete test.db
  sqlite3 db test.db
  execsql { 
................................................................................
    CREATE TABLE t2(x, y INTEGER REFERENCES t1);
  }
  db2 eval {
    PRAGMA foreign_key_list(t2);
  }
} {0 0 t1 y {} {NO ACTION} {NO ACTION} NONE}

database_never_corrupt
finish_test