SQLite

  if( pIdxKey ){
    xRecordCompare = sqlite3VdbeFindCompare(pIdxKey);
    assert( pIdxKey->default_rc==1 
         || pIdxKey->default_rc==0 
         || pIdxKey->default_rc==-1
    );
  }else{
    xRecordCompare = 0; /* All keys are integers */
  }

  rc = moveToRoot(pCur);
  if( rc ){
    return rc;
  }
  assert( pCur->pgnoRoot==0 || pCur->apPage[pCur->iPage] );

  return pIdx->zColAff;
}

/*
** Compute the affinity string for table pTab, if it has not already been
** computed.  As an optimization, omit trailing SQLITE_AFF_NONE affinities.
**
** If the affinity exists (if it is no entirely SQLITE_AFF_NONE values) and
** if iReg>0 then code an OP_Affinity opcode that will set the affinities
** for register iReg and following.  Or if affinities exists and iReg==0,
** then just set the P4 operand of the previous opcode (which should  be
** an OP_MakeRecord) to the affinity string.
**
** A column affinity string has one character per column:
**
**  Character      Column affinity
**  ------------------------------
**  'a'            TEXT
**  'b'            NONE
**  'c'            NUMERIC
**  'd'            INTEGER

      sqlite3VdbeChangeP4(v, -1, zColAff, i);
    }
  }
}

/*
** Return non-zero if the table pTab in database iDb or any of its indices
** have been opened at any point in the VDBE program. This is used to see if 

** a statement of the form  "INSERT INTO <iDb, pTab> SELECT ..." can 
** run without using a temporary table for the results of the SELECT. 
*/
static int readsTable(Parse *p, int iDb, Table *pTab){
  Vdbe *v = sqlite3GetVdbe(p);
  int i;
  int iEnd = sqlite3VdbeCurrentAddr(v);
#ifndef SQLITE_OMIT_VIRTUALTABLE
  VTable *pVTab = IsVirtual(pTab) ? sqlite3GetVTable(p->db, pTab) : 0;

/*
** Invoke this macro on memory cells just prior to changing the
** value of the cell.  This macro verifies that shallow copies are
** not misused.  A shallow copy of a string or blob just copies a
** pointer to the string or blob, not the content.  If the original
** is changed while the copy is still in use, the string or blob might
** be changed out from under the copy.  This macro verifies that nothing
** like that ever happens.
*/
#ifdef SQLITE_DEBUG
# define memAboutToChange(P,M) sqlite3VdbeMemAboutToChange(P,M)
#else
# define memAboutToChange(P,M)
#endif

  break;
}

/* Opcode: Once P1 P2 * * *
**
** Check if OP_Once flag P1 is set. If so, jump to instruction P2. Otherwise,
** set the flag and fall through to the next instruction.  In other words,
** this opcode causes all following opcodes up through P2 (but not including
** P2) to run just once and to be skipped on subsequent times through the loop.
*/
case OP_Once: {             /* jump */
  assert( pOp->p1<p->nOnceFlag );
  VdbeBranchTaken(p->aOnceFlag[pOp->p1]!=0, 2);
  if( p->aOnceFlag[pOp->p1] ){
    pc = pOp->p2-1;
  }else{

      ** callgrind, this causes a certain test case to hit the CPU 4.7 
      ** percent less (x86 linux, gcc version 4.1.2, -O6) than if 
      ** sqlite3MemRelease() were called from here. With -O2, this jumps
      ** to 6.6 percent. The test case is inserting 1000 rows into a table 
      ** with no indexes using a single prepared INSERT statement, bind() 
      ** and reset(). Inserts are grouped into a transaction.
      */
      testcase( p->flags & MEM_Agg );
      testcase( p->flags & MEM_Dyn );
      testcase( p->flags & MEM_Frame );
      testcase( p->flags & MEM_RowSet );
      if( p->flags&(MEM_Agg|MEM_Dyn|MEM_Frame|MEM_RowSet) ){
        sqlite3VdbeMemRelease(p);
      }else if( p->zMalloc ){
        sqlite3DbFree(db, p->zMalloc);
        p->zMalloc = 0;
      }

    case 0: {  /* NULL */
      pMem->flags = MEM_Null;
      break;
    }
    case 1: { /* 1-byte signed integer */
      pMem->u.i = ONE_BYTE_INT(buf);
      pMem->flags = MEM_Int;
      testcase( pMem->u.i<0 );
      return 1;
    }
    case 2: { /* 2-byte signed integer */
      pMem->u.i = TWO_BYTE_INT(buf);
      pMem->flags = MEM_Int;
      testcase( pMem->u.i<0 );
      return 2;
    }
    case 3: { /* 3-byte signed integer */
      pMem->u.i = THREE_BYTE_INT(buf);
      pMem->flags = MEM_Int;
      testcase( pMem->u.i<0 );
      return 3;
    }
    case 4: { /* 4-byte signed integer */
      y = FOUR_BYTE_UINT(buf);
      pMem->u.i = (i64)*(int*)&y;
      pMem->flags = MEM_Int;
      testcase( pMem->u.i<0 );
      return 4;
    }
    case 5: { /* 6-byte signed integer */
      pMem->u.i = FOUR_BYTE_UINT(buf+2) + (((i64)1)<<32)*TWO_BYTE_INT(buf);
      pMem->flags = MEM_Int;
      testcase( pMem->u.i<0 );
      return 6;
    }
    case 6:   /* 8-byte signed integer */
    case 7: { /* IEEE floating point */
#if !defined(NDEBUG) && !defined(SQLITE_OMIT_FLOATING_POINT)
      /* Verify that integers and floating point values use the same
      ** byte order.  Or, that if SQLITE_MIXED_ENDIAN_64BIT_FLOAT is

#endif
      x = FOUR_BYTE_UINT(buf);
      y = FOUR_BYTE_UINT(buf+4);
      x = (x<<32) | y;
      if( serial_type==6 ){
        pMem->u.i = *(i64*)&x;
        pMem->flags = MEM_Int;
        testcase( pMem->u.i<0 );
      }else{
        assert( sizeof(x)==8 && sizeof(pMem->r)==8 );
        swapMixedEndianFloat(x);
        memcpy(&pMem->r, &x, sizeof(x));
        pMem->flags = sqlite3IsNaN(pMem->r) ? MEM_Null : MEM_Real;
      }
      return 8;

*/
static i64 vdbeRecordDecodeInt(u32 serial_type, const u8 *aKey){
  u32 y;
  assert( CORRUPT_DB || (serial_type>=1 && serial_type<=9 && serial_type!=7) );
  switch( serial_type ){
    case 0:
    case 1:
      testcase( aKey[0]&0x80 );
      return ONE_BYTE_INT(aKey);
    case 2:
      testcase( aKey[0]&0x80 );
      return TWO_BYTE_INT(aKey);
    case 3:
      testcase( aKey[0]&0x80 );
      return THREE_BYTE_INT(aKey);
    case 4: {
      testcase( aKey[0]&0x80 );
      y = FOUR_BYTE_UINT(aKey);
      return (i64)*(int*)&y;
    }
    case 5: {
      testcase( aKey[0]&0x80 );
      return FOUR_BYTE_UINT(aKey+2) + (((i64)1)<<32)*TWO_BYTE_INT(aKey);
    }
    case 6: {
      u64 x = FOUR_BYTE_UINT(aKey);
      testcase( aKey[0]&0x80 );
      x = (x<<32) | FOUR_BYTE_UINT(aKey+4);
      return (i64)*(i64*)&x;
    }
  }

  return (serial_type - 8);
}

  assert( idx1<=szHdr1 || CORRUPT_DB );
  do{
    u32 serial_type;

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

        }
      }
    }

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

  i64 lhs;
  UNUSED_PARAMETER(bSkip);

  assert( bSkip==0 );
  switch( serial_type ){
    case 1: { /* 1-byte signed integer */
      lhs = ONE_BYTE_INT(aKey);
      testcase( lhs<0 );
      break;
    }
    case 2: { /* 2-byte signed integer */
      lhs = TWO_BYTE_INT(aKey);
      testcase( lhs<0 );
      break;
    }
    case 3: { /* 3-byte signed integer */
      lhs = THREE_BYTE_INT(aKey);
      testcase( lhs<0 );
      break;
    }
    case 4: { /* 4-byte signed integer */
      y = FOUR_BYTE_UINT(aKey);
      lhs = (i64)*(int*)&y;
      testcase( lhs<0 );
      break;
    }
    case 5: { /* 6-byte signed integer */
      lhs = FOUR_BYTE_UINT(aKey+2) + (((i64)1)<<32)*TWO_BYTE_INT(aKey);
      testcase( lhs<0 );
      break;
    }
    case 6: { /* 8-byte signed integer */
      x = FOUR_BYTE_UINT(aKey);
      x = (x<<32) | FOUR_BYTE_UINT(aKey+4);
      lhs = *(i64*)&x;
      testcase( lhs<0 );
      break;
    }
    case 8: 
      lhs = 0;
      break;
    case 9:
      lhs = 1;

    }else{
      p->r1 = -1;
      p->r2 = 1;
    }
    if( (flags & MEM_Int) ){
      return vdbeRecordCompareInt;
    }
    testcase( flags & MEM_Real );
    testcase( flags & MEM_Null );
    testcase( flags & MEM_Blob );
    if( (flags & (MEM_Real|MEM_Null|MEM_Blob))==0 && p->pKeyInfo->aColl[0]==0 ){

      assert( flags & MEM_Str );
      return vdbeRecordCompareString;
    }
  }

  return sqlite3VdbeRecordCompare;
}