**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.341 2004/05/27 19:59:32 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*
................................................................................
  int p1 = pOp->p1;  /* P1 value of the opcode */
  int p2 = pOp->p2;  /* column number to retrieve */
  Cursor *pC = 0;    /* The VDBE cursor */
  char *zRec;        /* Pointer to record-data from stack or pseudo-table. */
  BtCursor *pCrsr;   /* The BTree cursor */
  u32 *aType;        /* aType[i] holds the numeric type of the i-th column */
  u32 *aOffset;      /* aOffset[i] is offset to start of data for i-th column */
  u64 nField;        /* number of fields in the record */
  u32 szHdr;         /* Number of bytes in the record header */
  int len;           /* The length of the serialized data for the column */
  int offset = 0;    /* Offset into the data */
  int idx;           /* Index into the header */
  int i;             /* Loop counter */
  char *zData;       /* Part of the record being decoded */
  Mem sMem;          /* For storing the record being decoded */
................................................................................
  if( zRec ){
    zData = &zRec[aOffset[p2]];
  }else{
    len = sqlite3VdbeSerialTypeLen(aType[p2]);
    getBtreeMem(pCrsr, aOffset[p2], len, pC->keyAsData, &sMem);
    zData = sMem.z;
  }
  sqlite3VdbeSerialGet(zData, aType[p2], pTos, p->db->enc);

  if( rc!=SQLITE_OK ){
    goto abort_due_to_error;
  }
  Release(&sMem);

  /* Release the aType[] memory if we are not dealing with cursor */
  if( !pC ){
................................................................................
  assert( pData0>=p->aStack );
  zAffinity = pOp->p3;

  /* Loop through the elements that will make up the record to figure
  ** out how much space is required for the new record.
  */
  for(pRec=pData0; pRec<=pTos; pRec++){
    u64 serial_type;
    if( zAffinity ){
      applyAffinity(pRec, zAffinity[pRec-pData0], db->enc);
    }
    serial_type = sqlite3VdbeSerialType(pRec);
    nData += sqlite3VdbeSerialTypeLen(serial_type);
    nHdr += sqlite3VarintLen(serial_type);
  }
................................................................................
    goto no_mem;
  }

  /* Write the record */
  zCsr = zNewRecord;
  zCsr += sqlite3PutVarint(zCsr, nHdr);
  for(pRec=pData0; pRec<=pTos; pRec++){
    u64 serial_type = sqlite3VdbeSerialType(pRec);
    zCsr += sqlite3PutVarint(zCsr, serial_type);      /* serial type */
  }
  for(pRec=pData0; pRec<=pTos; pRec++){
    zCsr += sqlite3VdbeSerialPut(zCsr, pRec);  /* serial data */
  }

  /* If zCsr has not been advanced exactly nByte bytes, then one
................................................................................
  ** to store the coerced values serial-type and blob, and add this
  ** quantity to nByte.
  **
  ** TODO: Figure out if the in-place coercion causes a problem for
  ** OP_MakeKey when P2 is 0 (used by DISTINCT).
  */
  for(pRec=pData0; pRec<=pTos; pRec++){
    u64 serial_type;
    if( zAffinity ){
      applyAffinity(pRec, zAffinity[pRec-pData0], db->enc);
    }
    if( pRec->flags&MEM_Null ){
      containsNull = 1;
    }
    serial_type = sqlite3VdbeSerialType(pRec);
................................................................................
  zKey = (char *)sqliteMallocRaw(nByte);
  if( !zKey ){
    goto no_mem;
  }
  
  /* Build the key in the buffer pointed to by zKey. */
  for(pRec=pData0; pRec<=pTos; pRec++){
    u64 serial_type = sqlite3VdbeSerialType(pRec);
    offset += sqlite3PutVarint(&zKey[offset], serial_type);
    offset += sqlite3VdbeSerialPut(&zKey[offset], pRec);
  }
  if( addRowid ){
    zKey[offset++] = '\0';
    offset += sqlite3PutVarint(&zKey[offset], rowid);
  }
................................................................................
**
** P1 is a cursor opened on an index. Push the first field from the
** current index key onto the stack.
*/
case OP_IdxColumn: {
  char *zData;
  i64 n;
  u64 serial_type;
  int len;
  int freeZData = 0;
  BtCursor *pCsr;

  assert( 0==p->apCsr[pOp->p1]->intKey );
  pCsr = p->apCsr[pOp->p1]->pCursor;
  rc = sqlite3BtreeKeySize(pCsr, &n);
................................................................................
    goto abort_due_to_error;
  }
  if( n>10 ) n = 10;

  zData = (char *)sqlite3BtreeKeyFetch(pCsr, n);
  assert( zData );

  len = sqlite3GetVarint(zData, &serial_type);
  n = sqlite3VdbeSerialTypeLen(serial_type);

  zData = (char *)sqlite3BtreeKeyFetch(pCsr, len+n);
  if( !zData ){
    zData = (char *)sqliteMalloc(n);
    if( !zData ){
      goto no_mem;
................................................................................
      goto abort_due_to_error;
    }
    freeZData = 1;
    len = 0;
  }

  pTos++;
  sqlite3VdbeSerialGet(&zData[len], serial_type, pTos, p->db->enc);

  if( freeZData ){
    sqliteFree(zData);
  }
  break;
}

/* Opcode: FullKey P1 * *
................................................................................
      /* Find the start of the varint by searching backwards for a 0x00
      ** byte. If one does not exists, then intepret the whole 9 bytes as a
      ** varint.
      */
      while( len && buf[len-1] ){
        len--;
      }
      sqlite3GetVarint(&buf[len], &sz);
      pTos->flags = MEM_Int;
      pTos->i = sz;
    }
#endif
  }else{
    pTos->flags = MEM_Null;
  }
................................................................................
  const char *z;

  assert( pTos>=p->aStack );
  assert( pTos->flags & MEM_Blob );
  z = pTos->z;
  n = pTos->n;
  for(k=0; k<n && i>0; i--){
    u64 serial_type;
    k += sqlite3GetVarint(&z[k], &serial_type);
    if( serial_type==6 ){   /* Serial type 6 is a NULL */
      pc = pOp->p2-1;
      break;
    }
    k += sqlite3VdbeSerialTypeLen(serial_type);
  }
  Release(pTos);

**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.342 2004/05/28 01:39:01 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*
................................................................................
  int p1 = pOp->p1;  /* P1 value of the opcode */
  int p2 = pOp->p2;  /* column number to retrieve */
  Cursor *pC = 0;    /* The VDBE cursor */
  char *zRec;        /* Pointer to record-data from stack or pseudo-table. */
  BtCursor *pCrsr;   /* The BTree cursor */
  u32 *aType;        /* aType[i] holds the numeric type of the i-th column */
  u32 *aOffset;      /* aOffset[i] is offset to start of data for i-th column */
  u32 nField;        /* number of fields in the record */
  u32 szHdr;         /* Number of bytes in the record header */
  int len;           /* The length of the serialized data for the column */
  int offset = 0;    /* Offset into the data */
  int idx;           /* Index into the header */
  int i;             /* Loop counter */
  char *zData;       /* Part of the record being decoded */
  Mem sMem;          /* For storing the record being decoded */
................................................................................
  if( zRec ){
    zData = &zRec[aOffset[p2]];
  }else{
    len = sqlite3VdbeSerialTypeLen(aType[p2]);
    getBtreeMem(pCrsr, aOffset[p2], len, pC->keyAsData, &sMem);
    zData = sMem.z;
  }
  sqlite3VdbeSerialGet(zData, aType[p2], pTos);
  pTos->enc = db->enc;
  if( rc!=SQLITE_OK ){
    goto abort_due_to_error;
  }
  Release(&sMem);

  /* Release the aType[] memory if we are not dealing with cursor */
  if( !pC ){
................................................................................
  assert( pData0>=p->aStack );
  zAffinity = pOp->p3;

  /* Loop through the elements that will make up the record to figure
  ** out how much space is required for the new record.
  */
  for(pRec=pData0; pRec<=pTos; pRec++){
    u32 serial_type;
    if( zAffinity ){
      applyAffinity(pRec, zAffinity[pRec-pData0], db->enc);
    }
    serial_type = sqlite3VdbeSerialType(pRec);
    nData += sqlite3VdbeSerialTypeLen(serial_type);
    nHdr += sqlite3VarintLen(serial_type);
  }
................................................................................
    goto no_mem;
  }

  /* Write the record */
  zCsr = zNewRecord;
  zCsr += sqlite3PutVarint(zCsr, nHdr);
  for(pRec=pData0; pRec<=pTos; pRec++){
    u32 serial_type = sqlite3VdbeSerialType(pRec);
    zCsr += sqlite3PutVarint(zCsr, serial_type);      /* serial type */
  }
  for(pRec=pData0; pRec<=pTos; pRec++){
    zCsr += sqlite3VdbeSerialPut(zCsr, pRec);  /* serial data */
  }

  /* If zCsr has not been advanced exactly nByte bytes, then one
................................................................................
  ** to store the coerced values serial-type and blob, and add this
  ** quantity to nByte.
  **
  ** TODO: Figure out if the in-place coercion causes a problem for
  ** OP_MakeKey when P2 is 0 (used by DISTINCT).
  */
  for(pRec=pData0; pRec<=pTos; pRec++){
    u32 serial_type;
    if( zAffinity ){
      applyAffinity(pRec, zAffinity[pRec-pData0], db->enc);
    }
    if( pRec->flags&MEM_Null ){
      containsNull = 1;
    }
    serial_type = sqlite3VdbeSerialType(pRec);
................................................................................
  zKey = (char *)sqliteMallocRaw(nByte);
  if( !zKey ){
    goto no_mem;
  }
  
  /* Build the key in the buffer pointed to by zKey. */
  for(pRec=pData0; pRec<=pTos; pRec++){
    u32 serial_type = sqlite3VdbeSerialType(pRec);
    offset += sqlite3PutVarint(&zKey[offset], serial_type);
    offset += sqlite3VdbeSerialPut(&zKey[offset], pRec);
  }
  if( addRowid ){
    zKey[offset++] = '\0';
    offset += sqlite3PutVarint(&zKey[offset], rowid);
  }
................................................................................
**
** P1 is a cursor opened on an index. Push the first field from the
** current index key onto the stack.
*/
case OP_IdxColumn: {
  char *zData;
  i64 n;
  u32 serial_type;
  int len;
  int freeZData = 0;
  BtCursor *pCsr;

  assert( 0==p->apCsr[pOp->p1]->intKey );
  pCsr = p->apCsr[pOp->p1]->pCursor;
  rc = sqlite3BtreeKeySize(pCsr, &n);
................................................................................
    goto abort_due_to_error;
  }
  if( n>10 ) n = 10;

  zData = (char *)sqlite3BtreeKeyFetch(pCsr, n);
  assert( zData );

  len = sqlite3GetVarint32(zData, &serial_type);
  n = sqlite3VdbeSerialTypeLen(serial_type);

  zData = (char *)sqlite3BtreeKeyFetch(pCsr, len+n);
  if( !zData ){
    zData = (char *)sqliteMalloc(n);
    if( !zData ){
      goto no_mem;
................................................................................
      goto abort_due_to_error;
    }
    freeZData = 1;
    len = 0;
  }

  pTos++;
  sqlite3VdbeSerialGet(&zData[len], serial_type, pTos);
  pTos->enc = db->enc;
  if( freeZData ){
    sqliteFree(zData);
  }
  break;
}

/* Opcode: FullKey P1 * *
................................................................................
      /* Find the start of the varint by searching backwards for a 0x00
      ** byte. If one does not exists, then intepret the whole 9 bytes as a
      ** varint.
      */
      while( len && buf[len-1] ){
        len--;
      }
      sqlite3GetVarint32(&buf[len], &sz);
      pTos->flags = MEM_Int;
      pTos->i = sz;
    }
#endif
  }else{
    pTos->flags = MEM_Null;
  }
................................................................................
  const char *z;

  assert( pTos>=p->aStack );
  assert( pTos->flags & MEM_Blob );
  z = pTos->z;
  n = pTos->n;
  for(k=0; k<n && i>0; i--){
    u32 serial_type;
    k += sqlite3GetVarint32(&z[k], &serial_type);
    if( serial_type==6 ){   /* Serial type 6 is a NULL */
      pc = pOp->p2-1;
      break;
    }
    k += sqlite3VdbeSerialTypeLen(serial_type);
  }
  Release(pTos);

void sqlite3VdbeAggReset(Agg*);
void sqlite3VdbeKeylistFree(Keylist*);
void sqliteVdbePopStack(Vdbe*,int);
int sqlite3VdbeCursorMoveto(Cursor*);
#if !defined(NDEBUG) || defined(VDBE_PROFILE)
void sqlite3VdbePrintOp(FILE*, int, Op*);
#endif
int sqlite3VdbeSerialTypeLen(u64);
u64 sqlite3VdbeSerialType(Mem *);
int sqlite3VdbeSerialPut(unsigned char *, Mem *);
int sqlite3VdbeSerialGet(const unsigned char *, u64, Mem *, u8 enc);

int sqlite2BtreeKeyCompare(BtCursor *, const void *, int, int, int *);
int sqlite3VdbeIdxKeyCompare(Cursor*, int , const unsigned char*, int*);
int sqlite3VdbeIdxRowid(BtCursor *, i64 *);
int sqlite3MemCompare(const Mem*, const Mem*, const CollSeq*);
int sqlite3VdbeKeyCompare(void*,int,const void*,int, const void*);
int sqlite3VdbeRowCompare(void*,int,const void*,int, const void*);

void sqlite3VdbeAggReset(Agg*);
void sqlite3VdbeKeylistFree(Keylist*);
void sqliteVdbePopStack(Vdbe*,int);
int sqlite3VdbeCursorMoveto(Cursor*);
#if !defined(NDEBUG) || defined(VDBE_PROFILE)
void sqlite3VdbePrintOp(FILE*, int, Op*);
#endif
int sqlite3VdbeSerialTypeLen(u32);
u32 sqlite3VdbeSerialType(Mem*);
int sqlite3VdbeSerialPut(unsigned char*, Mem*);
int sqlite3VdbeSerialGet(const unsigned char*, u32, Mem*);

int sqlite2BtreeKeyCompare(BtCursor *, const void *, int, int, int *);
int sqlite3VdbeIdxKeyCompare(Cursor*, int , const unsigned char*, int*);
int sqlite3VdbeIdxRowid(BtCursor *, i64 *);
int sqlite3MemCompare(const Mem*, const Mem*, const CollSeq*);
int sqlite3VdbeKeyCompare(void*,int,const void*,int, const void*);
int sqlite3VdbeRowCompare(void*,int,const void*,int, const void*);

**    N>=13 and odd        (N-13)/2        text
**
*/

/*
** Return the serial-type for the value stored in pMem.
*/
u64 sqlite3VdbeSerialType(Mem *pMem){
  int flags = pMem->flags;

  if( flags&MEM_Null ){
    return 6;
  }
  if( flags&MEM_Int ){
    /* Figure out whether to use 1, 2, 4 or 8 bytes. */
................................................................................
  }
  return 0;
}

/*
** Return the length of the data corresponding to the supplied serial-type.
*/
int sqlite3VdbeSerialTypeLen(u64 serial_type){
  assert( serial_type!=0 );
  switch(serial_type){
    case 6: return 0;                  /* NULL */
    case 1: return 1;                  /* 1 byte integer */
    case 2: return 2;                  /* 2 byte integer */
    case 3: return 4;                  /* 4 byte integer */
    case 4: return 8;                  /* 8 byte integer */
................................................................................

/*
** Write the serialized data blob for the value stored in pMem into 
** buf. It is assumed that the caller has allocated sufficient space.
** Return the number of bytes written.
*/ 
int sqlite3VdbeSerialPut(unsigned char *buf, Mem *pMem){
  u64 serial_type = sqlite3VdbeSerialType(pMem);
  int len;

  assert( serial_type!=0 );
 
  /* NULL */
  if( serial_type==6 ){
    return 0;
................................................................................

/*
** Deserialize the data blob pointed to by buf as serial type serial_type
** and store the result in pMem.  Return the number of bytes read.
*/ 
int sqlite3VdbeSerialGet(
  const unsigned char *buf,     /* Buffer to deserialize from */
  u64 serial_type,              /* Serial type to deserialize */
  Mem *pMem,                    /* Memory cell to write value into */
  u8 enc      /* Text encoding. Used to determine nul term. character */
){
  int len;

  assert( serial_type!=0 );

  /* memset(pMem, 0, sizeof(pMem)); */
  pMem->flags = 0;
................................................................................
  /* String or blob */
  assert( serial_type>=12 );
  len = sqlite3VdbeSerialTypeLen(serial_type);
  pMem->z = (char *)buf;
  pMem->n = len;
  if( serial_type&0x01 ){
    pMem->flags = MEM_Str | MEM_Ephem;
    pMem->enc = enc;
  }else{
    pMem->flags = MEM_Blob | MEM_Ephem;
  }
  sqlite3VdbeMemMakeWriteable(pMem);
  return len;
}

................................................................................
  int nKey2, const void *pKey2
){
  KeyInfo *pKeyInfo = (KeyInfo*)userData;
  int offset1 = 0;
  int offset2 = 0;
  int i = 0;
  int rc = 0;
  u8 enc = pKeyInfo->enc;
  const unsigned char *aKey1 = (const unsigned char *)pKey1;
  const unsigned char *aKey2 = (const unsigned char *)pKey2;
  
  assert( pKeyInfo!=0 );
  while( offset1<nKey1 && offset2<nKey2 ){
    Mem mem1;
    Mem mem2;
    u64 serial_type1;
    u64 serial_type2;

    /* Read the serial types for the next element in each key. */
    offset1 += sqlite3GetVarint(&aKey1[offset1], &serial_type1);
    offset2 += sqlite3GetVarint(&aKey2[offset2], &serial_type2);

    /* If either of the varints just read in are 0 (not a type), then
    ** this is the end of the keys. The remaining data in each key is
    ** the varint rowid. Compare these as signed integers and return
    ** the result.
    */
    if( !serial_type1 || !serial_type2 ){
      assert( !serial_type1 && !serial_type2 );
      sqlite3GetVarint(&aKey1[offset1], &serial_type1);
      sqlite3GetVarint(&aKey2[offset2], &serial_type2);
      if( serial_type1 < serial_type2 ){
        rc = -1;
      }else if( serial_type1 > serial_type2 ){
        rc = +1;
      }else{
        rc = 0;
      }
................................................................................
    assert( i<pKeyInfo->nField );

    /* Assert that there is enough space left in each key for the blob of
    ** data to go with the serial type just read. This assert may fail if
    ** the file is corrupted.  Then read the value from each key into mem1
    ** and mem2 respectively.
    */
    offset1 += sqlite3VdbeSerialGet(&aKey1[offset1], serial_type1, &mem1, enc);
    offset2 += sqlite3VdbeSerialGet(&aKey2[offset2], serial_type2, &mem2, enc);

    rc = sqlite3MemCompare(&mem1, &mem2, pKeyInfo->aColl[i]);
    if( mem1.flags&MEM_Dyn ){
      sqliteFree(mem1.z);
    }
    if( mem2.flags&MEM_Dyn ){
      sqliteFree(mem2.z);
................................................................................
    idx2 += sqlite3GetVarint32(&aKey2[idx2], &serial_type2);

    /* Assert that there is enough space left in each key for the blob of
    ** data to go with the serial type just read. This assert may fail if
    ** the file is corrupted.  Then read the value from each key into mem1
    ** and mem2 respectively.
    */
    d1 += sqlite3VdbeSerialGet(&aKey1[d1], serial_type1, &mem1, 0);
    d2 += sqlite3VdbeSerialGet(&aKey2[d2], serial_type2, &mem2, 0);

    rc = sqlite3MemCompare(&mem1, &mem2, pKeyInfo->aColl[i]);
    if( mem1.flags&MEM_Dyn ){
      sqliteFree(mem1.z);
    }
    if( mem2.flags&MEM_Dyn ){
      sqliteFree(mem2.z);

**    N>=13 and odd        (N-13)/2        text
**
*/

/*
** Return the serial-type for the value stored in pMem.
*/
u32 sqlite3VdbeSerialType(Mem *pMem){
  int flags = pMem->flags;

  if( flags&MEM_Null ){
    return 6;
  }
  if( flags&MEM_Int ){
    /* Figure out whether to use 1, 2, 4 or 8 bytes. */
................................................................................
  }
  return 0;
}

/*
** Return the length of the data corresponding to the supplied serial-type.
*/
int sqlite3VdbeSerialTypeLen(u32 serial_type){
  assert( serial_type!=0 );
  switch(serial_type){
    case 6: return 0;                  /* NULL */
    case 1: return 1;                  /* 1 byte integer */
    case 2: return 2;                  /* 2 byte integer */
    case 3: return 4;                  /* 4 byte integer */
    case 4: return 8;                  /* 8 byte integer */
................................................................................

/*
** Write the serialized data blob for the value stored in pMem into 
** buf. It is assumed that the caller has allocated sufficient space.
** Return the number of bytes written.
*/ 
int sqlite3VdbeSerialPut(unsigned char *buf, Mem *pMem){
  u32 serial_type = sqlite3VdbeSerialType(pMem);
  int len;

  assert( serial_type!=0 );
 
  /* NULL */
  if( serial_type==6 ){
    return 0;
................................................................................

/*
** Deserialize the data blob pointed to by buf as serial type serial_type
** and store the result in pMem.  Return the number of bytes read.
*/ 
int sqlite3VdbeSerialGet(
  const unsigned char *buf,     /* Buffer to deserialize from */
  u32 serial_type,              /* Serial type to deserialize */
  Mem *pMem                     /* Memory cell to write value into */

){
  int len;

  assert( serial_type!=0 );

  /* memset(pMem, 0, sizeof(pMem)); */
  pMem->flags = 0;
................................................................................
  /* String or blob */
  assert( serial_type>=12 );
  len = sqlite3VdbeSerialTypeLen(serial_type);
  pMem->z = (char *)buf;
  pMem->n = len;
  if( serial_type&0x01 ){
    pMem->flags = MEM_Str | MEM_Ephem;

  }else{
    pMem->flags = MEM_Blob | MEM_Ephem;
  }
  sqlite3VdbeMemMakeWriteable(pMem);
  return len;
}

................................................................................
  int nKey2, const void *pKey2
){
  KeyInfo *pKeyInfo = (KeyInfo*)userData;
  int offset1 = 0;
  int offset2 = 0;
  int i = 0;
  int rc = 0;

  const unsigned char *aKey1 = (const unsigned char *)pKey1;
  const unsigned char *aKey2 = (const unsigned char *)pKey2;
  
  assert( pKeyInfo!=0 );
  while( offset1<nKey1 && offset2<nKey2 ){
    Mem mem1;
    Mem mem2;
    u32 serial_type1;
    u32 serial_type2;

    /* Read the serial types for the next element in each key. */
    offset1 += sqlite3GetVarint32(&aKey1[offset1], &serial_type1);
    offset2 += sqlite3GetVarint32(&aKey2[offset2], &serial_type2);

    /* If either of the varints just read in are 0 (not a type), then
    ** this is the end of the keys. The remaining data in each key is
    ** the varint rowid. Compare these as signed integers and return
    ** the result.
    */
    if( !serial_type1 || !serial_type2 ){
      assert( !serial_type1 && !serial_type2 );
      sqlite3GetVarint32(&aKey1[offset1], &serial_type1);
      sqlite3GetVarint32(&aKey2[offset2], &serial_type2);
      if( serial_type1 < serial_type2 ){
        rc = -1;
      }else if( serial_type1 > serial_type2 ){
        rc = +1;
      }else{
        rc = 0;
      }
................................................................................
    assert( i<pKeyInfo->nField );

    /* Assert that there is enough space left in each key for the blob of
    ** data to go with the serial type just read. This assert may fail if
    ** the file is corrupted.  Then read the value from each key into mem1
    ** and mem2 respectively.
    */
    offset1 += sqlite3VdbeSerialGet(&aKey1[offset1], serial_type1, &mem1);
    offset2 += sqlite3VdbeSerialGet(&aKey2[offset2], serial_type2, &mem2);

    rc = sqlite3MemCompare(&mem1, &mem2, pKeyInfo->aColl[i]);
    if( mem1.flags&MEM_Dyn ){
      sqliteFree(mem1.z);
    }
    if( mem2.flags&MEM_Dyn ){
      sqliteFree(mem2.z);
................................................................................
    idx2 += sqlite3GetVarint32(&aKey2[idx2], &serial_type2);

    /* Assert that there is enough space left in each key for the blob of
    ** data to go with the serial type just read. This assert may fail if
    ** the file is corrupted.  Then read the value from each key into mem1
    ** and mem2 respectively.
    */
    d1 += sqlite3VdbeSerialGet(&aKey1[d1], serial_type1, &mem1);
    d2 += sqlite3VdbeSerialGet(&aKey2[d2], serial_type2, &mem2);

    rc = sqlite3MemCompare(&mem1, &mem2, pKeyInfo->aColl[i]);
    if( mem1.flags&MEM_Dyn ){
      sqliteFree(mem1.z);
    }
    if( mem2.flags&MEM_Dyn ){
      sqliteFree(mem2.z);