SQLite

  p5 = binaryCompareP5(pLeft, pRight, jumpIfNull);
  addr = sqlite3VdbeAddOp4(pParse->pVdbe, opcode, in2, dest, in1,
                           (void*)p4, P4_COLLSEQ);
  sqlite3VdbeChangeP5(pParse->pVdbe, (u8)p5);
  return addr;
}

/*
** If the expression passed as the only argument is of type TK_VECTOR 
** return the number of expressions in the vector. Or, if the expression
** is a sub-select, return the number of columns in the sub-select. For
** any other type of expression, return 1.
*/
int sqlite3ExprVectorSize(Expr *pExpr){
  if( (pExpr->flags & EP_Vector)==0 ) return 1;
  if( pExpr->flags & EP_xIsSelect ){
    return pExpr->x.pSelect->pEList->nExpr;
  }
  return pExpr->x.pList->nExpr;
}

static Expr *exprVectorField(Expr *pVector, int i){
  if( (pVector->flags & EP_Vector)==0 ){
    assert( i==0 );
    return pVector;
  }else if( pVector->flags & EP_xIsSelect ){
    return pVector->x.pSelect->pEList->a[i].pExpr;
  }
  return pVector->x.pList->a[i].pExpr;
}

static void codeVectorCompare(Parse *pParse, Expr *pExpr, int dest){
  Vdbe *v = pParse->pVdbe;

** pX is the RHS of an IN operator.  If pX is a SELECT statement 
** that can be simplified to a direct table access, then return
** a pointer to the SELECT statement.  If pX is not a SELECT statement,
** or if the SELECT statement needs to be manifested into a transient
** table, then return NULL.
*/
#ifndef SQLITE_OMIT_SUBQUERY
static Select *isCandidateForInOpt(Expr *pX, int bNullSensitive){
  Select *p;
  SrcList *pSrc;
  ExprList *pEList;

  Table *pTab;
  int i;
  if( !ExprHasProperty(pX, EP_xIsSelect) ) return 0;  /* Not a subquery */
  if( ExprHasProperty(pX, EP_VarSelect)  ) return 0;  /* Correlated subq */
  p = pX->x.pSelect;
  if( p->pPrior ) return 0;              /* Not a compound SELECT */
  if( p->selFlags & (SF_Distinct|SF_Aggregate) ){
    testcase( (p->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct );
    testcase( (p->selFlags & (SF_Distinct|SF_Aggregate))==SF_Aggregate );

  if( pSrc->nSrc!=1 ) return 0;          /* Single term in FROM clause */
  if( pSrc->a[0].pSelect ) return 0;     /* FROM is not a subquery or view */
  pTab = pSrc->a[0].pTab;
  assert( pTab!=0 );
  assert( pTab->pSelect==0 );            /* FROM clause is not a view */
  if( IsVirtual(pTab) ) return 0;        /* FROM clause not a virtual table */
  pEList = p->pEList;

  /* All SELECT results must be columns. If the SELECT returns more than
  ** one column and the bNullSensitive flag is set, all returned columns
  ** must be declared NOT NULL. */
  for(i=0; i<pEList->nExpr; i++){
    Expr *pRes = pEList->a[i].pExpr;
    if( pRes->op!=TK_COLUMN ) return 0;
    assert( pRes->iTable==pSrc->a[0].iCursor );  /* Not a correlated subquery */
    if( pEList->nExpr>1 && bNullSensitive ){
      if( pTab->aCol[pRes->iColumn].notNull==0 ) return 0;
    }
  }
  return p;
}
#endif /* SQLITE_OMIT_SUBQUERY */

/*
** Code an OP_Once instruction and allocate space for its flag. Return the 
** address of the new instruction.

  assert( pX->op==TK_IN );
  mustBeUnique = (inFlags & IN_INDEX_LOOP)!=0;

  /* Check to see if an existing table or index can be used to
  ** satisfy the query.  This is preferable to generating a new 
  ** ephemeral table.
  */
  if( pParse->nErr==0 && (p = isCandidateForInOpt(pX, prRhsHasNull!=0))!=0 ){
    sqlite3 *db = pParse->db;              /* Database connection */
    Table *pTab;                           /* Table <table>. */
    ExprList *pEList = p->pEList;
    int nExpr = pEList->nExpr;
    i16 iDb;                               /* Database idx for pTab */

    assert( p->pEList!=0 );             /* Because of isCandidateForInOpt(p) */
    assert( p->pEList->a[0].pExpr!=0 ); /* Because of isCandidateForInOpt(p) */
    assert( p->pSrc!=0 );               /* Because of isCandidateForInOpt(p) */
    pTab = p->pSrc->a[0].pTab;



    /* Code an OP_Transaction and OP_TableLock for <table>. */
    iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
    sqlite3CodeVerifySchema(pParse, iDb);
    sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);

    /* This function is only called from two places. In both cases the vdbe
    ** has already been allocated. So assume sqlite3GetVdbe() is always
    ** successful here.
    */
    assert(v);
    if( nExpr==1 && pEList->a[0].pExpr->iColumn<0 ){
      int iAddr = sqlite3CodeOnce(pParse);
      VdbeCoverage(v);

      sqlite3OpenTable(pParse, iTab, iDb, pTab, OP_OpenRead);
      eType = IN_INDEX_ROWID;

      sqlite3VdbeJumpHere(v, iAddr);
    }else{
      Index *pIdx;                         /* Iterator variable */
      int affinity_ok = 1;
      int i;

      /* Check that the affinity that will be used to perform each 
      ** comparison is the same as the affinity of each column. If
      ** it not, it is not possible to use any index.  */
      for(i=0; i<nExpr && affinity_ok; i++){
        Expr *pLhs = exprVectorField(pX->pLeft, i);
        int iCol = pEList->a[i].pExpr->iColumn;
        char idxaff = pTab->aCol[iCol].affinity;
        char cmpaff = sqlite3CompareAffinity(pLhs, idxaff);
        switch( cmpaff ){
          case SQLITE_AFF_BLOB:
            break;
          case SQLITE_AFF_TEXT:
            affinity_ok = (idxaff==SQLITE_AFF_TEXT);
            break;
          default:
            affinity_ok = sqlite3IsNumericAffinity(idxaff);
        }
      }

      /* The collation sequence used by the comparison. If an index is to
      ** be used in place of a temp-table, it must be ordered according
      ** to this collation sequence.  */

      for(pIdx=pTab->pIndex; pIdx && eType==0 && affinity_ok; pIdx=pIdx->pNext){
        if( pIdx->nKeyCol<nExpr ) continue;
        if( mustBeUnique && (pIdx->nKeyCol!=nExpr || !IsUniqueIndex(pIdx)) ){
          continue;
        }




        for(i=0; i<nExpr; i++){
          Expr *pLhs = exprVectorField(pX->pLeft, i);
          Expr *pRhs = pEList->a[i].pExpr;
          CollSeq *pReq = sqlite3BinaryCompareCollSeq(pParse, pLhs, pRhs);
          int j;


          for(j=0; j<nExpr; j++){
            if( pIdx->aiColumn[j]!=pRhs->iColumn ) continue;
            assert( pIdx->azColl[j] );
            if( sqlite3StrICmp(pReq->zName, pIdx->azColl[j])!=0 ) continue;
            break;
          }
          if( j==nExpr ) break;
        }

        if( i==nExpr ){
          int iAddr = sqlite3CodeOnce(pParse); VdbeCoverage(v);
          sqlite3VdbeAddOp3(v, OP_OpenRead, iTab, pIdx->tnum, iDb);
          sqlite3VdbeSetP4KeyInfo(pParse, pIdx);
          VdbeComment((v, "%s", pIdx->zName));
          assert( IN_INDEX_INDEX_DESC == IN_INDEX_INDEX_ASC+1 );
          eType = IN_INDEX_INDEX_ASC + pIdx->aSortOrder[0];

          if( prRhsHasNull && nExpr==1 
           && !pTab->aCol[pEList->a[0].pExpr->iColumn].notNull 
          ){
#ifdef SQLITE_ENABLE_COLUMN_USED_MASK
            i64 mask = (1<<nExpr)-1;
            sqlite3VdbeAddOp4Dup8(v, OP_ColumnsUsed, 
                iTab, 0, 0, (u8*)&mask, P4_INT64);
#endif
            *prRhsHasNull = ++pParse->nMem;
            sqlite3SetHasNullFlag(v, iTab, *prRhsHasNull);
          }
          sqlite3VdbeJumpHere(v, iAddr);
        }
      }

  if( eType==0
   && (inFlags & IN_INDEX_NOOP_OK)
   && !ExprHasProperty(pX, EP_xIsSelect)
   && (!sqlite3InRhsIsConstant(pX) || pX->x.pList->nExpr<=2)
  ){
    eType = IN_INDEX_NOOP;
  }


  if( eType==0 ){
    /* Could not find an existing table or index to use as the RHS b-tree.
    ** We will have to generate an ephemeral table to do the job.
    */
    u32 savedNQueryLoop = pParse->nQueryLoop;
    int rMayHaveNull = 0;