SQLite

    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

    r.eqSeen = 0;
    rc = sqlite3BtreeMovetoUnpacked(pC->uc.pCursor, &r, 0, 0, &res);
    if( rc!=SQLITE_OK ){
      goto abort_due_to_error;
    }
    if( eqOnly && r.eqSeen==0 ){
      assert( res!=0 );

  assert( pC->uc.pCursor!=0 );
  assert( pC->isTable==0 );
  pFree = 0;
  if( pOp->p4.i>0 ){
    r.pKeyInfo = pC->pKeyInfo;
    r.nField = (u16)pOp->p4.i;
    r.aMem = pIn3;
#ifdef SQLITE_DEBUG
    for(ii=0; ii<r.nField; ii++){
      assert( memIsValid(&r.aMem[ii]) );
      assert( (r.aMem[ii].flags & MEM_Zero)==0 || r.aMem[ii].n==0 );

      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 );

  }
}

/*
** The input pBlob is guaranteed to be a Blob that is not marked
** with MEM_Zero.  Return true if it could be a zero-blob.
*/
static int isAllZero(const char *z, int n){
  int i;
  for(i=0; i<n; i++){
    if( z[i] ) return 0;
  }
  return 1;
}

/*
** Compare two blobs.  Return negative, zero, or positive if the first
** is less than, equal to, or greater than the second, respectively.
** If one blob is a prefix of the other, then the shorter is the lessor.
*/

  assert( (pB1->flags & MEM_Zero)==0 || n1==0 );
  assert( (pB2->flags & MEM_Zero)==0 || n2==0 );

  if( (pB1->flags|pB2->flags) & MEM_Zero ){
    if( pB1->flags & pB2->flags & MEM_Zero ){
      return pB1->u.nZero - pB2->u.nZero;
    }else if( pB1->flags & MEM_Zero ){
      if( !isAllZero(pB2->z, pB2->n) ) return -1;
      return pB1->u.nZero - n2;
    }else{
      if( !isAllZero(pB1->z, pB1->n) ) return +1;
      return n1 - pB2->u.nZero;
    }
  }
  c = memcmp(pB1->z, pB2->z, n1>n2 ? n2 : n1);
  if( c ) return c;
  return n1 - n2;
}

          if( rc==0 ) rc = mem1.n - pRhs->n; 
        }
      }
    }

    /* RHS is a blob */
    else if( pRhs->flags & MEM_Blob ){
      assert( (pRhs->flags & MEM_Zero)==0 || pRhs->n==0 );
      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 ){
          pPKey2->errCode = (u8)SQLITE_CORRUPT_BKPT;
          return 0;                /* Corruption */
        }else if( pRhs->flags & MEM_Zero ){
          if( !isAllZero((const char*)&aKey1[d1],nStr) ){
            rc = 1;
          }else{
            rc = nStr - pRhs->u.nZero;
          }
        }else{
          int nCmp = MIN(nStr, pRhs->n);
          rc = memcmp(&aKey1[d1], pRhs->z, nCmp);
          if( rc==0 ) rc = nStr - pRhs->n;
        }
      }
    }

/*
** Change pMem so that its MEM_Str or MEM_Blob value is stored in
** MEM.zMalloc, where it can be safely written.
**
** Return SQLITE_OK on success or SQLITE_NOMEM if malloc fails.
*/
int sqlite3VdbeMemMakeWriteable(Mem *pMem){

  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
  assert( (pMem->flags&MEM_RowSet)==0 );
  if( (pMem->flags & (MEM_Str|MEM_Blob))!=0 ){
    if( ExpandBlob(pMem) ) return SQLITE_NOMEM;

    if( pMem->szMalloc==0 || pMem->z!=pMem->zMalloc ){
      if( sqlite3VdbeMemGrow(pMem, pMem->n + 2, 1) ){
        return SQLITE_NOMEM_BKPT;
      }
      pMem->z[pMem->n] = 0;
      pMem->z[pMem->n+1] = 0;
      pMem->flags |= MEM_Term;
    }
  }
  pMem->flags &= ~MEM_Ephem;
#ifdef SQLITE_DEBUG
  pMem->pScopyFrom = 0;
#endif

  return SQLITE_OK;