SQLite

    int iRowid = ++pParse->nMem;    /* Used for storing rowid values. */
    int regRowid;                   /* Actual register containing rowids */

    /* Collect rowids of every row to be deleted.
    */
    sqlite3VdbeAddOp2(v, OP_Null, 0, iRowSet);
    pWInfo = sqlite3WhereBegin(
        pParse, pTabList, pWhere, 0, 0, WHERE_DUPLICATES_OK, 0
    );
    if( pWInfo==0 ) goto delete_from_cleanup;
    regRowid = sqlite3ExprCodeGetColumn(pParse, pTab, -1, iCur, iRowid, 0);
    sqlite3VdbeAddOp2(v, OP_RowSetAdd, iRowSet, regRowid);
    if( db->flags & SQLITE_CountRows ){
      sqlite3VdbeAddOp2(v, OP_AddImm, memCnt, 1);
    }

  sNameContext.pParse = pParse;
  sqlite3ResolveExprNames(&sNameContext, pWhere);

  /* Create VDBE to loop through the entries in pSrc that match the WHERE
  ** clause. If the constraint is not deferred, throw an exception for
  ** each row found. Otherwise, for deferred constraints, increment the
  ** deferred constraint counter by nIncr for each row selected.  */
  pWInfo = sqlite3WhereBegin(pParse, pSrc, pWhere, 0, 0, 0, 0);
  if( nIncr>0 && pFKey->isDeferred==0 ){
    sqlite3ParseToplevel(pParse)->mayAbort = 1;
  }
  sqlite3VdbeAddOp2(v, OP_FkCounter, pFKey->isDeferred, nIncr);
  if( pWInfo ){
    sqlite3WhereEnd(pWInfo);
  }

  }

  /* Aggregate and non-aggregate queries are handled differently */
  if( !isAgg && pGroupBy==0 ){
    ExprList *pDist = (isDistinct ? p->pEList : 0);

    /* Begin the database scan. */
    pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pOrderBy, pDist, 0,0);
    if( pWInfo==0 ) goto select_end;
    if( pWInfo->nRowOut < p->nSelectRow ) p->nSelectRow = pWInfo->nRowOut;

    /* If sorting index that was created by a prior OP_OpenEphemeral 
    ** instruction ended up not being needed, then change the OP_OpenEphemeral
    ** into an OP_Noop.
    */

      /* Begin a loop that will extract all source rows in GROUP BY order.
      ** This might involve two separate loops with an OP_Sort in between, or
      ** it might be a single loop that uses an index to extract information
      ** in the right order to begin with.
      */
      sqlite3VdbeAddOp2(v, OP_Gosub, regReset, addrReset);
      pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pGroupBy, 0, 0, 0);
      if( pWInfo==0 ) goto select_end;
      if( pGroupBy==0 ){
        /* The optimizer is able to deliver rows in group by order so
        ** we do not have to sort.  The OP_OpenEphemeral table will be
        ** cancelled later because we still need to use the pKeyInfo
        */
        pGroupBy = p->pGroupBy;

        }
  
        /* This case runs if the aggregate has no GROUP BY clause.  The
        ** processing is much simpler since there is only a single row
        ** of output.
        */
        resetAccumulator(pParse, &sAggInfo);
        pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pMinMax,0,flag,0);
        if( pWInfo==0 ){
          sqlite3ExprListDelete(db, pDel);
          goto select_end;
        }
        updateAccumulator(pParse, &sAggInfo);
        if( !pMinMax && flag ){
          sqlite3VdbeAddOp2(v, OP_Goto, 0, pWInfo->iBreak);

    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 */
      } *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;

  /* The following field is really not part of the current level.  But
  ** we need a place to cache virtual table index information for each
  ** virtual table in the FROM clause and the WhereLevel structure is
  ** a convenient place since there is one WhereLevel for each FROM clause
  ** element.

int sqlite3IsReadOnly(Parse*, Table*, int);
void sqlite3OpenTable(Parse*, int iCur, int iDb, Table*, int);
#if defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) && !defined(SQLITE_OMIT_SUBQUERY)
Expr *sqlite3LimitWhere(Parse *, SrcList *, Expr *, ExprList *, Expr *, Expr *, char *);
#endif
void sqlite3DeleteFrom(Parse*, SrcList*, Expr*);
void sqlite3Update(Parse*, SrcList*, ExprList*, Expr*, int);
WhereInfo *sqlite3WhereBegin(
    Parse*,SrcList*,Expr*,ExprList**,ExprList*,u16,int);
void sqlite3WhereEnd(WhereInfo*);
int sqlite3ExprCodeGetColumn(Parse*, Table*, int, int, int, u8);
void sqlite3ExprCodeGetColumnOfTable(Vdbe*, Table*, int, int, int);
void sqlite3ExprCodeMove(Parse*, int, int, int);
void sqlite3ExprCodeCopy(Parse*, int, int, int);
void sqlite3ExprCacheStore(Parse*, int, int, int);
void sqlite3ExprCachePush(Parse*);

    goto update_cleanup;
  }

  /* Begin the database scan
  */
  sqlite3VdbeAddOp3(v, OP_Null, 0, regRowSet, regOldRowid);
  pWInfo = sqlite3WhereBegin(
      pParse, pTabList, pWhere, 0, 0, WHERE_ONEPASS_DESIRED, 0
  );
  if( pWInfo==0 ) goto update_cleanup;
  okOnePass = pWInfo->okOnePass;

  /* Remember the rowid of every item to be updated.
  */
  sqlite3VdbeAddOp2(v, OP_Rowid, iCur, regOldRowid);

  /* Evaluate the equality constraints
  */
  assert( pIdx->nColumn>=nEq );
  for(j=0; j<nEq; j++){
    int r1;
    int k = pIdx->aiColumn[j];
    pTerm = findTerm(pWC, iCur, k, notReady, pLevel->plan.wsFlags, pIdx);
    if( pTerm==0 ) break;
    /* The following true for indices with redundant columns. 
    ** Ex: CREATE INDEX i1 ON t1(a,b,a); SELECT * FROM t1 WHERE a=0 AND b=0; */
    testcase( (pTerm->wtFlags & TERM_CODED)!=0 );
    testcase( pTerm->wtFlags & TERM_VIRTUAL ); /* EV: R-30575-11662 */
    r1 = codeEqualityTerm(pParse, pTerm, pLevel, regBase+j);
    if( r1!=regBase+j ){
      if( nReg==1 ){

    **          Return     2                # Jump back to the Gosub
    **
    **       B: <after the loop>
    **
    */
    WhereClause *pOrWc;    /* The OR-clause broken out into subterms */
    SrcList *pOrTab;       /* Shortened table list or OR-clause generation */
    Index *pCov = 0;             /* Potential covering index (or NULL) */
    int iCovCur = pParse->nTab++;  /* Cursor used for index scans (if any) */

    int regReturn = ++pParse->nMem;           /* Register used with OP_Gosub */
    int regRowset = 0;                        /* Register for RowSet object */
    int regRowid = 0;                         /* Register holding rowid */
    int iLoopBody = sqlite3VdbeMakeLabel(v);  /* Start of loop body */
    int iRetInit;                             /* Address of regReturn init */
    int untestedTerms = 0;             /* Some terms not completely tested */
    int ii;                            /* Loop counter */
    Expr *pAndExpr = 0;                /* An ".. AND (...)" expression */
   
    pTerm = pLevel->plan.u.pTerm;
    assert( pTerm!=0 );
    assert( pTerm->eOperator==WO_OR );
    assert( (pTerm->wtFlags & TERM_ORINFO)!=0 );
    pOrWc = &pTerm->u.pOrInfo->wc;
    pLevel->op = OP_Return;
    pLevel->p1 = regReturn;

    /* Set up a new SrcList in pOrTab containing the table being scanned
    ** by this loop in the a[0] slot and all notReady tables in a[1..] slots.
    ** This becomes the SrcList in the recursive call to sqlite3WhereBegin().
    */
    if( pWInfo->nLevel>1 ){
      int nNotReady;                 /* The number of notReady tables */
      struct SrcList_item *origSrc;     /* Original list of tables */
      nNotReady = pWInfo->nLevel - iLevel - 1;

        if( pAndExpr ){
          pAndExpr->pLeft = pOrExpr;
          pOrExpr = pAndExpr;
        }
        /* Loop through table entries that match term pOrTerm. */
        pSubWInfo = sqlite3WhereBegin(pParse, pOrTab, pOrExpr, 0, 0,
                        WHERE_OMIT_OPEN_CLOSE | WHERE_AND_ONLY |
                        WHERE_FORCE_TABLE | WHERE_ONETABLE_ONLY, iCovCur);
        assert( pSubWInfo || pParse->nErr || pParse->db->mallocFailed );
        if( pSubWInfo ){
          WhereLevel *pLvl;
          explainOneScan(
              pParse, pOrTab, &pSubWInfo->a[0], iLevel, pLevel->iFrom, 0
          );
          if( (wctrlFlags & WHERE_DUPLICATES_OK)==0 ){
            int iSet = ((ii==pOrWc->nTerm-1)?-1:ii);
            int r;
            r = sqlite3ExprCodeGetColumn(pParse, pTabItem->pTab, -1, iCur, 
                                         regRowid, 0);
            sqlite3VdbeAddOp4Int(v, OP_RowSetTest, regRowset,
                                 sqlite3VdbeCurrentAddr(v)+2, r, iSet);
          }
          sqlite3VdbeAddOp2(v, OP_Gosub, regReturn, iLoopBody);

          /* The pSubWInfo->untestedTerms flag means that this OR term
          ** contained one or more AND term from a notReady table.  The
          ** terms from the notReady table could not be tested and will
          ** need to be tested later.
          */
          if( pSubWInfo->untestedTerms ) untestedTerms = 1;

          /* If all of the OR-connected terms are optimized using the same
          ** index, and the index is opened using the same cursor number
          ** by each call to sqlite3WhereBegin() made by this loop, it may
          ** be possible to use that index as a covering index.
          **
          ** If the call to sqlite3WhereBegin() above resulted in a scan that
          ** uses an index, and this is either the first OR-connected term
          ** processed or the index is the same as that used by all previous
          ** terms, set pCov to the candidate covering index. Otherwise, set 
          ** pCov to NULL to indicate that no candidate covering index will 
          ** be available.
          */
          pLvl = &pSubWInfo->a[0];
          if( (pLvl->plan.wsFlags & WHERE_INDEXED)!=0
           && (pLvl->plan.wsFlags & WHERE_TEMP_INDEX)==0
           && (ii==0 || pLvl->plan.u.pIdx==pCov)
          ){
            assert( pLvl->iIdxCur==iCovCur );
            pCov = pLvl->plan.u.pIdx;
          }else{
            pCov = 0;
          }

          /* Finish the loop through table entries that match term pOrTerm. */
          sqlite3WhereEnd(pSubWInfo);
        }
      }
    }
    pLevel->u.pCovidx = pCov;
    pLevel->iIdxCur = iCovCur;
    if( pAndExpr ){
      pAndExpr->pLeft = 0;
      sqlite3ExprDelete(pParse->db, pAndExpr);
    }
    sqlite3VdbeChangeP1(v, iRetInit, sqlite3VdbeCurrentAddr(v));
    sqlite3VdbeAddOp2(v, OP_Goto, 0, pLevel->addrBrk);
    sqlite3VdbeResolveLabel(v, iLoopBody);

*/
WhereInfo *sqlite3WhereBegin(
  Parse *pParse,        /* The parser context */
  SrcList *pTabList,    /* A list of all tables to be scanned */
  Expr *pWhere,         /* The WHERE clause */
  ExprList **ppOrderBy, /* An ORDER BY clause, or NULL */
  ExprList *pDistinct,  /* The select-list for DISTINCT queries - or NULL */
  u16 wctrlFlags,       /* One of the WHERE_* flags defined in sqliteInt.h */
  int iIdxCur           /* If WHERE_ONETABLE_ONLY is set, index cursor number */
){
  int i;                     /* Loop counter */
  int nByteWInfo;            /* Num. bytes allocated for WhereInfo struct */
  int nTabList;              /* Number of elements in pTabList */
  WhereInfo *pWInfo;         /* Will become the return value of this function */
  Vdbe *v = pParse->pVdbe;   /* The virtual database engine */
  Bitmask notReady;          /* Cursors that are not yet positioned */

      pWInfo->eDistinct = WHERE_DISTINCT_ORDERED;
    }
    andFlags &= bestPlan.plan.wsFlags;
    pLevel->plan = bestPlan.plan;
    testcase( bestPlan.plan.wsFlags & WHERE_INDEXED );
    testcase( bestPlan.plan.wsFlags & WHERE_TEMP_INDEX );
    if( bestPlan.plan.wsFlags & (WHERE_INDEXED|WHERE_TEMP_INDEX) ){
      if( (wctrlFlags & WHERE_ONETABLE_ONLY) 
       && (bestPlan.plan.wsFlags & WHERE_TEMP_INDEX)==0 
      ){
        pLevel->iIdxCur = iIdxCur;
      }else{
        pLevel->iIdxCur = pParse->nTab++;
      }
    }else{
      pLevel->iIdxCur = -1;
    }
    notReady &= ~getMask(pMaskSet, pTabList->a[bestJ].iCursor);
    pLevel->iFrom = (u8)bestJ;
    if( bestPlan.plan.nRow>=(double)1 ){
      pParse->nQueryLoop *= bestPlan.plan.nRow;

  */
  sqlite3VdbeResolveLabel(v, pWInfo->iBreak);

  /* Close all of the cursors that were opened by sqlite3WhereBegin.
  */
  assert( pWInfo->nLevel==1 || pWInfo->nLevel==pTabList->nSrc );
  for(i=0, pLevel=pWInfo->a; i<pWInfo->nLevel; i++, pLevel++){
    Index *pIdx = 0;
    struct SrcList_item *pTabItem = &pTabList->a[pLevel->iFrom];
    Table *pTab = pTabItem->pTab;
    assert( pTab!=0 );
    if( (pTab->tabFlags & TF_Ephemeral)==0
     && pTab->pSelect==0
     && (pWInfo->wctrlFlags & WHERE_OMIT_OPEN_CLOSE)==0
    ){

    ** 
    ** Calls to the code generator in between sqlite3WhereBegin and
    ** sqlite3WhereEnd will have created code that references the table
    ** directly.  This loop scans all that code looking for opcodes
    ** that reference the table and converts them into opcodes that
    ** reference the index.
    */
    if( pLevel->plan.wsFlags & WHERE_INDEXED ){
      pIdx = pLevel->plan.u.pIdx;
    }else if( pLevel->plan.wsFlags & WHERE_MULTI_OR ){
      pIdx = pLevel->u.pCovidx;
    }
    if( pIdx && !db->mallocFailed){
      int k, j, last;
      VdbeOp *pOp;



      pOp = sqlite3VdbeGetOp(v, pWInfo->iTop);
      last = sqlite3VdbeCurrentAddr(v);
      for(k=pWInfo->iTop; k<last; k++, pOp++){
        if( pOp->p1!=pLevel->iTabCur ) continue;
        if( pOp->opcode==OP_Column ){
          for(j=0; j<pIdx->nColumn; j++){
            if( pOp->p2==pIdx->aiColumn[j] ){

# 2012 August 24
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this file is testing that an index may be used as a covering
# index when there are OR expressions in the WHERE clause. 
#


set testdir [file dirname $argv0]
source $testdir/tester.tcl
set ::testprefix whereD

do_execsql_test 1.1 {
  CREATE TABLE t(i,j,k,m,n);
  CREATE INDEX ijk ON t(i,j,k);
  CREATE INDEX jmn ON t(j,m,n);

  INSERT INTO t VALUES(3, 3, 'three', 3, 'tres');
  INSERT INTO t VALUES(2, 2, 'two', 2, 'dos');
  INSERT INTO t VALUES(1, 1, 'one', 1, 'uno');
  INSERT INTO t VALUES(4, 4, 'four', 4, 'cuatro');
}

do_execsql_test 1.2 {
  SELECT k FROM t WHERE (i=1 AND j=1) OR (i=2 AND j=2);
} {one two}
do_execsql_test 1.3 {
  SELECT k FROM t WHERE (i=1 AND j=1) OR (+i=2 AND j=2);
} {one two}
do_execsql_test 1.4 {
  SELECT n FROM t WHERE (i=1 AND j=1) OR (i=2 AND j=2);
} {uno dos}
do_execsql_test 1.5 {
  SELECT k, n FROM t WHERE (i=1 AND j=1) OR (i=2 AND j=2);
} {one uno two dos}
do_execsql_test 1.6 {
  SELECT k FROM t WHERE (i=1 AND j=1) OR (i=2 AND j=2) OR (i=3 AND j=3);
} {one two three}
do_execsql_test 1.7 {
  SELECT n FROM t WHERE (i=1 AND j=1) OR (i=2 AND j=2) OR (i=3 AND j=3);
} {uno dos tres}
do_execsql_test 1.8 {
  SELECT k FROM t WHERE (i=1 AND j=1) OR (j=2 AND m=2);
} {one two}
do_execsql_test 1.9 {
  SELECT k FROM t WHERE (i=1 AND j=1) OR (i=2 AND j=2) OR (j=3 AND m=3);
} {one two three}
do_execsql_test 1.10 {
  SELECT n FROM t WHERE (i=1 AND j=1) OR (i=2 AND j=2) OR (j=3 AND m=3);
} {uno dos tres}
do_execsql_test 1.11 {
  SELECT k FROM t WHERE (i=1 AND j=1) OR (j=2 AND m=2) OR (i=3 AND j=3);
} {one two three}
do_execsql_test 1.12 {
  SELECT n FROM t WHERE (i=1 AND j=1) OR (j=2 AND m=2) OR (i=3 AND j=3);
} {uno dos tres}
do_execsql_test 1.13 {
  SELECT k FROM t WHERE (j=1 AND m=1) OR (i=2 AND j=2) OR (i=3 AND j=3);
} {one two three}
do_execsql_test 1.14 {
  SELECT k FROM t WHERE (i=1 AND j=1) OR (j=2 AND i=2) OR (i=3 AND j=3);
} {one two three}
do_execsql_test 1.15 {
  SELECT k FROM t WHERE (i=1 AND j=2) OR (i=2 AND j=1) OR (i=3 AND j=4);
} {}
do_execsql_test 1.16 {
  SELECT k FROM t WHERE (i=1 AND (j=1 or j=2)) OR (i=3 AND j=3);
} {one three}

do_execsql_test 2.0 {
  CREATE TABLE t1(a,b,c,d);
  CREATE INDEX t1b ON t1(b);
  CREATE INDEX t1c ON t1(c);
  CREATE INDEX t1d ON t1(d);
  CREATE TABLE t2(x,y);
  CREATE INDEX t2y ON t2(y);
  
  INSERT INTO t1 VALUES(1,2,3,4);
  INSERT INTO t1 VALUES(5,6,7,8);
  INSERT INTO t2 VALUES(1,2);
  INSERT INTO t2 VALUES(2,7);
  INSERT INTO t2 VALUES(3,4);
} {}
do_execsql_test 2.1 {
  SELECT a, x FROM t1 JOIN t2 ON +y=d OR x=7 ORDER BY a, x;
} {1 3}
do_execsql_test 2.2 {
  SELECT a, x FROM t1 JOIN t2 ON y=d OR x=7 ORDER BY a, x;
} {1 3}


# Similar to [do_execsql_test], except that two elements are appended
# to the result - the string "search" and the number of times test variable
# sqlite3_search_count is incremented by running the supplied SQL. e.g.
# 
#   do_searchcount_test 1.0 { SELECT * FROM t1 } {x y search 2}
#
proc do_searchcount_test {tn sql res} {
  uplevel [subst -nocommands {
    do_test $tn {
      set ::sqlite_search_count 0
      concat [db eval {$sql}] search [set ::sqlite_search_count]
    } [list $res]
  }] 
}

do_execsql_test 3.0 {
  CREATE TABLE t3(a, b, c);
  CREATE UNIQUE INDEX i3 ON t3(a, b);
  INSERT INTO t3 VALUES(1, 'one', 'i');
  INSERT INTO t3 VALUES(3, 'three', 'iii');
  INSERT INTO t3 VALUES(6, 'six', 'vi');
  INSERT INTO t3 VALUES(2, 'two', 'ii');
  INSERT INTO t3 VALUES(4, 'four', 'iv');
  INSERT INTO t3 VALUES(5, 'five', 'v');

  CREATE TABLE t4(x PRIMARY KEY, y);
  INSERT INTO t4 VALUES('a', 'one');
  INSERT INTO t4 VALUES('b', 'two');
}

do_searchcount_test 3.1 {
  SELECT a, b FROM t3 WHERE (a=1 AND b='one') OR (a=2 AND b='two')
} {1 one 2 two search 2}

do_searchcount_test 3.2 {
  SELECT a, c FROM t3 WHERE (a=1 AND b='one') OR (a=2 AND b='two')
} {1 i 2 ii search 4}

do_searchcount_test 3.4.1 {
  SELECT y FROM t4 WHERE x='a'
} {one search 2}
do_searchcount_test 3.4.2 {
  SELECT a, b FROM t3 WHERE 
        (a=1 AND b=(SELECT y FROM t4 WHERE x='a')) 
     OR (a=2 AND b='two')
} {1 one 2 two search 4}
do_searchcount_test 3.4.3 {
  SELECT a, b FROM t3 WHERE 
        (a=2 AND b='two')
     OR (a=1 AND b=(SELECT y FROM t4 WHERE x='a')) 
} {2 two 1 one search 4}
do_searchcount_test 3.4.4 {
  SELECT a, b FROM t3 WHERE 
        (a=2 AND b=(SELECT y FROM t4 WHERE x='b')) 
     OR (a=1 AND b=(SELECT y FROM t4 WHERE x='a')) 
} {2 two 1 one search 6}

do_searchcount_test 3.5.1 {
  SELECT a, b FROM t3 WHERE (a=1 AND b='one') OR rowid=4
} {1 one 2 two search 2}
do_searchcount_test 3.5.2 {
  SELECT a, c FROM t3 WHERE (a=1 AND b='one') OR rowid=4
} {1 i 2 ii search 2}

finish_test