SQLite

  int p1, p2;           /* Operands of the opcode used to ends the loop */
  union {               /* Information that depends on plan.wsFlags */
    struct {
      int nIn;              /* Number of entries in aInLoop[] */
      struct InLoop {
        int iCur;              /* The VDBE cursor used by this IN operator */
        int addrInTop;         /* Top of the IN loop */
        u8 eEndLoopOp;         /* IN Loop terminator. OP_Next or OP_Prev */
      } *aInLoop;           /* Information about each nested IN operator */
    } in;                 /* Used when plan.wsFlags&WHERE_IN_ABLE */
    Index *pCovidx;       /* Possible covering index for WHERE_MULTI_OR */
  } u;
  double rOptCost;      /* "Optimal" cost for this level */

  /* The following field is really not part of the current level.  But

** There are separate WhereClause objects for the whole clause and for
** the subclauses "(b AND c)" and "(d AND e)".  The pOuter field of the
** subclauses points to the WhereClause object for the whole clause.
*/
struct WhereClause {
  Parse *pParse;           /* The parser context */
  WhereMaskSet *pMaskSet;  /* Mapping of table cursor numbers to bitmasks */

  WhereClause *pOuter;     /* Outer conjunction */
  u8 op;                   /* Split operator.  TK_AND or TK_OR */
  u16 wctrlFlags;          /* Might include WHERE_AND_ONLY */
  int nTerm;               /* Number of terms */
  int nSlot;               /* Number of entries in a[] */
  WhereTerm *a;            /* Each a[] describes a term of the WHERE cluase */
#if defined(SQLITE_SMALL_STACK)

){
  pWC->pParse = pParse;
  pWC->pMaskSet = pMaskSet;
  pWC->pOuter = 0;
  pWC->nTerm = 0;
  pWC->nSlot = ArraySize(pWC->aStatic);
  pWC->a = pWC->aStatic;

  pWC->wctrlFlags = wctrlFlags;
}

/* Forward reference */
static void whereClauseClear(WhereClause*);

/*

**     (B)     x=expr1 OR expr2=x OR x=expr3
**     (C)     t1.x=t2.y OR (t1.x=t2.z AND t1.y=15)
**     (D)     x=expr1 OR (y>11 AND y<22 AND z LIKE '*hello*')
**     (E)     (p.a=1 AND q.b=2 AND r.c=3) OR (p.x=4 AND q.y=5 AND r.z=6)
**
** CASE 1:
**
** If all subterms are of the form T.C=expr for some single column of C and
** a single table T (as shown in example B above) then create a new virtual
** term that is an equivalent IN expression.  In other words, if the term
** being analyzed is:
**
**      x = expr1  OR  expr2 = x  OR  x = expr3
**
** then create a new virtual term like this:

  if( db->mallocFailed ) return;
  assert( pOrWc->nTerm>=2 );

  /*
  ** Compute the set of tables that might satisfy cases 1 or 2.
  */
  indexable = ~(Bitmask)0;
  chngToIN = ~(Bitmask)0;
  for(i=pOrWc->nTerm-1, pOrTerm=pOrWc->a; i>=0 && indexable; i--, pOrTerm++){
    if( (pOrTerm->eOperator & WO_SINGLE)==0 ){
      WhereAndInfo *pAndInfo;
      assert( (pOrTerm->wtFlags & (TERM_ANDINFO|TERM_ORINFO))==0 );
      chngToIN = 0;
      pAndInfo = sqlite3DbMallocRaw(db, sizeof(*pAndInfo));
      if( pAndInfo ){

  WhereClause *pWC = p->pWC;      /* The WHERE clause */
  struct SrcList_item *pSrc = p->pSrc; /* The FROM clause term to search */
  Table *pTab = pSrc->pTab;
  sqlite3_index_info *pIdxInfo;
  struct sqlite3_index_constraint *pIdxCons;
  struct sqlite3_index_constraint_usage *pUsage;
  WhereTerm *pTerm;
  int i, j, k;
  int nOrderBy;
  int sortOrder;                  /* Sort order for IN clauses */
  int bAllowIN;                   /* Allow IN optimizations */
  double rCost;

  /* Make sure wsFlags is initialized to some sane value. Otherwise, if the 
  ** malloc in allocateIndexInfo() fails and this function returns leaving
  ** wsFlags in an uninitialized state, the caller may behave unpredictably.
  */

      pIdxInfo->nOrderBy = 0;
    }
  
    if( vtabBestIndex(pParse, pTab, pIdxInfo) ){
      return;
    }
  
    sortOrder = SQLITE_SO_ASC;
    pIdxCons = *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint;
    for(i=0; i<pIdxInfo->nConstraint; i++, pIdxCons++){
      if( pUsage[i].argvIndex>0 ){
        j = pIdxCons->iTermOffset;
        pTerm = &pWC->a[j];
        p->cost.used |= pTerm->prereqRight;
        if( (pTerm->eOperator & WO_IN)!=0 ){
          if( pUsage[i].omit==0 ){
            /* Do not attempt to use an IN constraint if the virtual table
            ** says that the equivalent EQ constraint cannot be safely omitted.
            ** If we do attempt to use such a constraint, some rows might be
            ** repeated in the output. */
            break;
          }
          for(k=0; k<pIdxInfo->nOrderBy; k++){
            if( pIdxInfo->aOrderBy[k].iColumn==pIdxCons->iColumn ){
              sortOrder = pIdxInfo->aOrderBy[k].desc;
              break;
            }
          }
        }
      }
    }
    if( i>=pIdxInfo->nConstraint ) break;
  }
  
  /* If there is an ORDER BY clause, and the selected virtual table index

  if( (SQLITE_BIG_DBL/((double)2))<rCost ){
    p->cost.rCost = (SQLITE_BIG_DBL/((double)2));
  }else{
    p->cost.rCost = rCost;
  }
  p->cost.plan.u.pVtabIdx = pIdxInfo;
  if( pIdxInfo->orderByConsumed ){
    assert( sortOrder==0 || sortOrder==1 );
    p->cost.plan.wsFlags |= WHERE_ORDERED + sortOrder*WHERE_REVERSE;
    p->cost.plan.nOBSat = nOrderBy;
  }else{
    p->cost.plan.nOBSat = p->i ? p->aLevel[p->i-1].plan.nOBSat : 0;
  }
  p->cost.plan.nEq = 0;
  pIdxInfo->nOrderBy = nOrderBy;

    /* If X is the column in the index and ORDER BY clause, check to see
    ** if there are any X= or X IS NULL constraints in the WHERE clause. */
    pConstraint = findTerm(p->pWC, base, iColumn, p->notReady,
                           WO_EQ|WO_ISNULL|WO_IN, pIdx);
    if( pConstraint==0 ){
      isEq = 0;
    }else if( (pConstraint->eOperator & WO_IN)!=0 ){
      isEq = 0;



    }else if( (pConstraint->eOperator & WO_ISNULL)!=0 ){
      uniqueNotNull = 0;
      isEq = 1;  /* "X IS NULL" means X has only a single value */
    }else if( pConstraint->prereqRight==0 ){
      isEq = 1;  /* Constraint "X=constant" means X has only a single value */
    }else{
      Expr *pRight = pConstraint->pExpr->pRight;

 
    /* If the index being considered is UNIQUE, and there is an equality 
    ** constraint for all columns in the index, then this search will find
    ** at most a single row. In this case set the WHERE_UNIQUE flag to 
    ** indicate this to the caller.
    **
    ** Otherwise, if the search may find more than one row, test to see if
    ** there is a range constraint on indexed column (pc.plan.nEq+1) that
    ** can be optimized using the index. 
    */
    if( pc.plan.nEq==pProbe->nColumn && pProbe->onError!=OE_None ){
      testcase( pc.plan.wsFlags & WHERE_COLUMN_IN );
      testcase( pc.plan.wsFlags & WHERE_COLUMN_NULL );
      if( (pc.plan.wsFlags & (WHERE_COLUMN_IN|WHERE_COLUMN_NULL))==0 ){
        pc.plan.wsFlags |= WHERE_UNIQUE;
        if( p->i==0 || (p->aLevel[p->i-1].plan.wsFlags & WHERE_ALL_UNIQUE)!=0 ){

*/
static void bestIndex(WhereBestIdx *p){
#ifndef SQLITE_OMIT_VIRTUALTABLE
  if( IsVirtual(p->pSrc->pTab) ){
    sqlite3_index_info *pIdxInfo = 0;
    p->ppIdxInfo = &pIdxInfo;
    bestVirtualIndex(p);
    assert( pIdxInfo!=0 || p->pParse->db->mallocFailed );
    if( pIdxInfo && pIdxInfo->needToFreeIdxStr ){
      sqlite3_free(pIdxInfo->idxStr);
    }
    sqlite3DbFree(p->pParse->db, pIdxInfo);
  }else
#endif
  {
    bestBtreeIndex(p);

    iReg = iTarget;
    sqlite3VdbeAddOp2(v, OP_Null, 0, iReg);
#ifndef SQLITE_OMIT_SUBQUERY
  }else{
    int eType;
    int iTab;
    struct InLoop *pIn;
    u8 bRev = (pLevel->plan.wsFlags & WHERE_REVERSE)!=0;

    assert( pX->op==TK_IN );
    iReg = iTarget;
    eType = sqlite3FindInIndex(pParse, pX, 0);
    iTab = pX->iTable;
    sqlite3VdbeAddOp2(v, bRev ? OP_Last : OP_Rewind, iTab, 0);
    assert( pLevel->plan.wsFlags & WHERE_IN_ABLE );
    if( pLevel->u.in.nIn==0 ){
      pLevel->addrNxt = sqlite3VdbeMakeLabel(v);
    }
    pLevel->u.in.nIn++;
    pLevel->u.in.aInLoop =
       sqlite3DbReallocOrFree(pParse->db, pLevel->u.in.aInLoop,
                              sizeof(pLevel->u.in.aInLoop[0])*pLevel->u.in.nIn);
    pIn = pLevel->u.in.aInLoop;
    if( pIn ){
      pIn += pLevel->u.in.nIn - 1;
      pIn->iCur = iTab;
      if( eType==IN_INDEX_ROWID ){
        pIn->addrInTop = sqlite3VdbeAddOp2(v, OP_Rowid, iTab, iReg);
      }else{
        pIn->addrInTop = sqlite3VdbeAddOp3(v, OP_Column, iTab, 0, iReg);
      }
      pIn->eEndLoopOp = bRev ? OP_Prev : OP_Next;
      sqlite3VdbeAddOp1(v, OP_IsNull, iReg);
    }else{
      pLevel->u.in.nIn = 0;
    }
#endif
  }
  disableTerm(pLevel, pTerm);

  ** the bitmask for all FROM clause terms to the left of the N-th term
  ** is (X-1).   An expression from the ON clause of a LEFT JOIN can use
  ** its Expr.iRightJoinTable value to find the bitmask of the right table
  ** of the join.  Subtracting one from the right table bitmask gives a
  ** bitmask for all tables to the left of the join.  Knowing the bitmask
  ** for all tables to the left of a left join is important.  Ticket #3015.
  **





  ** Note that bitmasks are created for all pTabList->nSrc tables in
  ** pTabList, not just the first nTabList tables.  nTabList is normally
  ** equal to pTabList->nSrc but might be shortened to 1 if the
  ** WHERE_ONETABLE_ONLY flag is set.
  */

  for(ii=0; ii<pTabList->nSrc; ii++){
    createMask(pMaskSet, pTabList->a[ii].iCursor);





  }
#ifndef NDEBUG
  {
    Bitmask toTheLeft = 0;
    for(ii=0; ii<pTabList->nSrc; ii++){
      Bitmask m = getMask(pMaskSet, pTabList->a[ii].iCursor);
      assert( (m-1)==toTheLeft );

    }
    if( pLevel->plan.wsFlags & WHERE_IN_ABLE && pLevel->u.in.nIn>0 ){
      struct InLoop *pIn;
      int j;
      sqlite3VdbeResolveLabel(v, pLevel->addrNxt);
      for(j=pLevel->u.in.nIn, pIn=&pLevel->u.in.aInLoop[j-1]; j>0; j--, pIn--){
        sqlite3VdbeJumpHere(v, pIn->addrInTop+1);
        sqlite3VdbeAddOp2(v, pIn->eEndLoopOp, pIn->iCur, pIn->addrInTop);
        sqlite3VdbeJumpHere(v, pIn->addrInTop-1);
      }
      sqlite3DbFree(db, pLevel->u.in.aInLoop);
    }
    sqlite3VdbeResolveLabel(v, pLevel->addrBrk);
    if( pLevel->iLeftJoin ){
      int addr;

    }
  } {1 0 4 2 1 9 3 1 16 4}
  do_test where-5.2 {
    count {
      SELECT * FROM t1 WHERE rowid+0 IN (1,2,3,1234) order by 1;
    }
  } {1 0 4 2 1 9 3 1 16 102}
  do_test where-5.3a {
    count {
      SELECT * FROM t1 WHERE w IN (-1,1,2,3) order by 1;
    }
  } {1 0 4 2 1 9 3 1 16 13}
  do_test where-5.3b {
    count {
      SELECT * FROM t1 WHERE w IN (3,-1,1,2) order by 1;
    }
  } {1 0 4 2 1 9 3 1 16 13}
  do_test where-5.3c {
    count {
      SELECT * FROM t1 WHERE w IN (3,2,-1,1,2) order by 1;
    }
  } {1 0 4 2 1 9 3 1 16 13}
  do_test where-5.3d {
    count {
      SELECT * FROM t1 WHERE w IN (-1,1,2,3) order by 1 DESC;
    }
  } {3 1 16 2 1 9 1 0 4 12}
  do_test where-5.4 {
    count {
      SELECT * FROM t1 WHERE w+0 IN (-1,1,2,3) order by 1;
    }
  } {1 0 4 2 1 9 3 1 16 102}
  do_test where-5.5 {
    count {

    }
  } {2 1 9 8}
  do_test where-5.15 {
    count {
      SELECT * FROM t1 WHERE x IN (1,7) AND y IN (9,16) ORDER BY 1;
    }
  } {2 1 9 3 1 16 11}
  do_test where-5.100 {
    db eval {
      SELECT w, x, y FROM t1 WHERE x IN (1,5) AND y IN (9,8,3025,1000,3969)
       ORDER BY x, y
    }
  } {2 1 9 54 5 3025 62 5 3969}
  do_test where-5.101 {
    db eval {
      SELECT w, x, y FROM t1 WHERE x IN (1,5) AND y IN (9,8,3025,1000,3969)
       ORDER BY x DESC, y DESC
    }
  } {62 5 3969 54 5 3025 2 1 9}
  do_test where-5.102 {
    db eval {
      SELECT w, x, y FROM t1 WHERE x IN (1,5) AND y IN (9,8,3025,1000,3969)
       ORDER BY x DESC, y
    }
  } {54 5 3025 62 5 3969 2 1 9}
  do_test where-5.103 {
    db eval {
      SELECT w, x, y FROM t1 WHERE x IN (1,5) AND y IN (9,8,3025,1000,3969)
       ORDER BY x, y DESC
    }
  } {2 1 9 62 5 3969 54 5 3025}
}

# This procedure executes the SQL.  Then it checks to see if the OP_Sort
# opcode was executed.  If an OP_Sort did occur, then "sort" is appended
# to the result.  If no OP_Sort happened, then "nosort" is appended.
#
# This procedure is used to check to make sure sorting is or is not

} {1 100 4 2 99 9 3 98 16 nosort}
do_test where-6.7 {
  cksort {
    SELECT * FROM t3 WHERE b>0 ORDER BY a LIMIT 3
  }
} {1 100 4 2 99 9 3 98 16 nosort}
ifcapable subquery {
  do_test where-6.8a {
    cksort {
      SELECT * FROM t3 WHERE a IN (3,5,7,1,9,4,2) ORDER BY a LIMIT 3
    }
  } {1 100 4 2 99 9 3 98 16 nosort}
  do_test where-6.8b {
    cksort {
      SELECT * FROM t3 WHERE a IN (3,5,7,1,9,4,2) ORDER BY a DESC LIMIT 3
    }
  } {9 92 100 7 94 64 5 96 36 nosort}
}
do_test where-6.9.1 {
  cksort {
    SELECT * FROM t3 WHERE a=1 AND c>0 ORDER BY a LIMIT 3
  }
} {1 100 4 nosort}
do_test where-6.9.1.1 {

        SELECT * FROM t1 WHERE z IN (SELECT 10207 UNION SELECT 10006)
                         AND y IN (SELECT 10000 UNION SELECT 10201)
                         AND x>0 AND x<10
        ORDER BY w
      }
    } {99 6 10000 10006 100 6 10201 10207 sort t1 i1zyx}
  }
  do_test where2-4.6a {
    queryplan {
      SELECT * FROM t1
       WHERE x IN (1,2,3,4,5,6,7,8)
         AND y IN (10000,10001,10002,10003,10004,10005)
       ORDER BY x
    }
  } {99 6 10000 10006 nosort t1 i1xy}
  do_test where2-4.6b {
    queryplan {
      SELECT * FROM t1
       WHERE x IN (1,2,3,4,5,6,7,8)
         AND y IN (10000,10001,10002,10003,10004,10005)
       ORDER BY x DESC
    }
  } {99 6 10000 10006 nosort t1 i1xy}
  do_test where2-4.6c {
    queryplan {
      SELECT * FROM t1
       WHERE x IN (1,2,3,4,5,6,7,8)
         AND y IN (10000,10001,10002,10003,10004,10005)
       ORDER BY x, y
    }
  } {99 6 10000 10006 nosort t1 i1xy}
  do_test where2-4.6d {
    queryplan {
      SELECT * FROM t1
       WHERE x IN (1,2,3,4,5,6,7,8)
         AND y IN (10000,10001,10002,10003,10004,10005)
       ORDER BY x, y DESC
    }
  } {99 6 10000 10006 sort t1 i1xy}

  # Duplicate entires on the RHS of an IN operator do not cause duplicate
  # output rows.
  #
  do_test where2-4.6x {
    queryplan {
      SELECT * FROM t1 WHERE z IN (10207,10006,10006,10207)
      ORDER BY w
    }
  } {99 6 10000 10006 100 6 10201 10207 sort t1 i1zyx}
  do_test where2-4.6y {
    queryplan {
      SELECT * FROM t1 WHERE z IN (10207,10006,10006,10207)
      ORDER BY w DESC
    }
  } {100 6 10201 10207 99 6 10000 10006 sort t1 i1zyx}
  ifcapable compound {
    do_test where2-4.7 {
      queryplan {
        SELECT * FROM t1 WHERE z IN (
           SELECT 10207 UNION ALL SELECT 10006
           UNION ALL SELECT 10006 UNION ALL SELECT 10207)
        ORDER BY w

do_test where2-5.1 {
  queryplan {
    SELECT * FROM t1 WHERE w=99 ORDER BY w
  }
} {99 6 10000 10006 nosort t1 i1w}

ifcapable subquery {
  do_test where2-5.2a {
    queryplan {
      SELECT * FROM t1 WHERE w IN (99) ORDER BY w
    }
  } {99 6 10000 10006 nosort t1 i1w}
  do_test where2-5.2b {
    queryplan {
      SELECT * FROM t1 WHERE w IN (99) ORDER BY w DESC
    }
  } {99 6 10000 10006 nosort t1 i1w}
}

# Verify that OR clauses get translated into IN operators.
#
set ::idx {}
ifcapable subquery {set ::idx i1w}
do_test where2-6.1.1 {