SQLite

  */
  if( !ExprHasAnyProperty(pExpr, EP_VarSelect) && !pParse->pTriggerTab ){
    int mem = ++pParse->nMem;
    sqlite3VdbeAddOp1(v, OP_If, mem);
    testAddr = sqlite3VdbeAddOp2(v, OP_Integer, 1, mem);
    assert( testAddr>0 || pParse->db->mallocFailed );
  }

#ifndef SQLITE_OMIT_EXPLAIN
  if( pParse->explain==2 ){
    char *zMsg = sqlite3MPrintf(
        pParse->db, "EXECUTE %s%s SUBQUERY %d", testAddr?"":"CORRELATED ",
        pExpr->op==TK_IN?"LIST":"SCALAR", pParse->iNextSelectId
    );
    sqlite3VdbeAddOp4(v, OP_Explain, pParse->iSelectId, 0, 0, zMsg, P4_DYNAMIC);
  }
#endif

  switch( pExpr->op ){
    case TK_IN: {
      char affinity;              /* Affinity of the LHS of the IN */
      KeyInfo keyInfo;            /* Keyinfo for the generated table */
      int addr;                   /* Address of OP_OpenEphemeral instruction */
      Expr *pLeft = pExpr->pLeft; /* the LHS of the IN operator */

  if( pParse->explain==2 ){
    Vdbe *v = pParse->pVdbe;
    char *zMsg = sqlite3MPrintf(pParse->db, "USE TEMP B-TREE FOR %s", zUsage);
    sqlite3VdbeAddOp4(v, OP_Explain, pParse->iSelectId, 0, 0, zMsg, P4_DYNAMIC);
  }
}
# define explainRestoreSelectId() pParse->iSelectId = iRestoreSelectId
# define explainAssignSelectId(pItem, id) pItem->iSelectId = id
#else
# define explainRestoreSelectId()
# define explainTempTable(y,z)
# define explainAssignSelectId(y,z)
#endif

/*
** If the inner loop was generated using a non-null pOrderBy argument,
** then the results were placed in a sorter.  After the loop is terminated
** we need to run the sorter and output the results.  The following
** routine generates the code needed to do that.

        isAgg = 1;
        p->selFlags |= SF_Aggregate;
      }
      i = -1;
    }else{
      sqlite3SelectDestInit(&dest, SRT_EphemTab, pItem->iCursor);
      assert( pItem->isPopulated==0 );
      explainAssignSelectId(pItem, pParse->iNextSelectId);
      sqlite3Select(pParse, pSub, &dest);
      pItem->isPopulated = 1;
    }
    if( /*pParse->nErr ||*/ db->mallocFailed ){
      goto select_end;
    }
    pParse->nHeight -= sqlite3SelectExprHeight(p);

    u8 notIndexed;    /* True if there is a NOT INDEXED clause */
    int iCursor;      /* The VDBE cursor number used to access this table */
    Expr *pOn;        /* The ON clause of a join */
    IdList *pUsing;   /* The USING clause of a join */
    Bitmask colUsed;  /* Bit N (1<<N) set if column N of pTab is used */
    char *zIndex;     /* Identifier from "INDEXED BY <zIndex>" clause */
    Index *pIndex;    /* Index structure corresponding to zIndex, if any */
#ifndef SQLITE_OMIT_EXPLAIN
    int iSelectId;    /* If pSelect!=0, the id of the sub-select in EQP */
#endif
  } a[1];             /* One entry for each identifier on the list */
};

/*
** Permitted values of the SrcList.a.jointype field
*/
#define JT_INNER     0x0001    /* Any kind of inner or cross join */

}

static void codeOneLoopExplain(
  Parse *pParse,                  /* Parse context */
  SrcList *pTabList,              /* Table list this loop refers to */
  WhereLevel *pLevel,             /* Scan to write OP_Explain opcode for */
  int iLevel,                     /* Value for "level" column of output */
  int iFrom,                      /* Value for "from" column of output */
  u16 wctrlFlags                  /* Flags passed to sqlite3WhereBegin() */
){
  if( pParse->explain==2 ){
    u32 flags = pLevel->plan.wsFlags;
    struct SrcList_item *pItem = &pTabList->a[pLevel->iFrom];
    Vdbe *v = pParse->pVdbe;
    sqlite3 *db = pParse->db;
    char *zMsg;
    sqlite3_int64 nRow;           /* Expected number of rows visited by scan */
    int iId = pParse->iSelectId;  /* Select id (left-most output column) */

    if( (flags&WHERE_MULTI_OR) || (wctrlFlags&WHERE_ONETABLE_ONLY) ) return;

    if( pItem->pSelect ){
      zMsg = sqlite3MPrintf(db, "SCAN SUBQUERY %d", pItem->iSelectId);
    }else{
      zMsg = sqlite3MPrintf(db, "SCAN TABLE %s", pItem->zName);
    }

    if( pItem->zAlias ){
      zMsg = sqlite3MAppendf(db, zMsg, "%s AS %s", zMsg, pItem->zAlias);
    }
    if( (flags & WHERE_INDEXED)!=0 ){
      char *zWhere = indexRangeText(db, pLevel, pItem->pTab);
      zMsg = sqlite3MAppendf(db, zMsg, "%s BY %s%sINDEX%s%s%s", zMsg, 
          ((flags & WHERE_TEMP_INDEX)?"AUTOMATIC ":""),
          ((flags & WHERE_IDX_ONLY)?"COVERING ":""),
          ((flags & WHERE_TEMP_INDEX)?"":" "),
          ((flags & WHERE_TEMP_INDEX)?"": pLevel->plan.u.pIdx->zName),
          zWhere
      );
      sqlite3DbFree(db, zWhere);
    }else if( flags & (WHERE_ROWID_EQ|WHERE_ROWID_RANGE) ){
      zMsg = sqlite3MAppendf(db, zMsg, "%s BY INTEGER PRIMARY KEY", zMsg);

      if( flags&WHERE_ROWID_EQ ){
        zMsg = sqlite3MAppendf(db, zMsg, "%s (rowid=?)", zMsg);
      }else if( flags&WHERE_BTM_LIMIT && flags&WHERE_TOP_LIMIT ){
        zMsg = sqlite3MAppendf(db, zMsg, "%s (rowid>? AND rowid<?)", zMsg);
      }else if( flags&WHERE_BTM_LIMIT ){
        zMsg = sqlite3MAppendf(db, zMsg, "%s (rowid>?)", zMsg);
      }else if( flags&WHERE_TOP_LIMIT ){
        zMsg = sqlite3MAppendf(db, zMsg, "%s (rowid<?)", zMsg);
      }
    }
#ifndef SQLITE_OMIT_VIRTUALTABLE
    else if( (flags & WHERE_VIRTUALTABLE)!=0 ){
      sqlite3_index_info *pVtabIdx = pLevel->plan.u.pVtabIdx;
      zMsg = sqlite3MAppendf(db, zMsg, "%s VIRTUAL TABLE INDEX %d:%s", zMsg,
                  pVtabIdx->idxNum, pVtabIdx->idxStr);
    }
#endif
    if( wctrlFlags&(WHERE_ORDERBY_MIN|WHERE_ORDERBY_MAX) ){
      nRow = 1;
    }else{
      nRow = (sqlite3_int64)pLevel->plan.nRow;
    }
    zMsg = sqlite3MAppendf(db, zMsg, "%s (~%lld rows)", zMsg, nRow);


    sqlite3VdbeAddOp4(v, OP_Explain, iId, iLevel, iFrom, zMsg, P4_DYNAMIC);

  }
}
#else
# define codeOneLoopExplain(u,v,w,x,y,z)
#endif /* SQLITE_OMIT_EXPLAIN */


/*
** Generate code for the start of the iLevel-th loop in the WHERE clause
** implementation described by pWInfo.
*/

        WhereInfo *pSubWInfo;          /* Info for single OR-term scan */
        /* Loop through table entries that match term pOrTerm. */
        pSubWInfo = sqlite3WhereBegin(pParse, pOrTab, pOrTerm->pExpr, 0,
                        WHERE_OMIT_OPEN | WHERE_OMIT_CLOSE |
                        WHERE_FORCE_TABLE | WHERE_ONETABLE_ONLY);
        if( pSubWInfo ){
          codeOneLoopExplain(
              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);
            sqlite3VdbeAddOp4Int(v, OP_RowSetTest, regRowset,

  /* Generate the code to do the search.  Each iteration of the for
  ** loop below generates code for a single nested loop of the VM
  ** program.
  */
  notReady = ~(Bitmask)0;
  for(i=0; i<nTabList; i++){
    WhereLevel *pLevel = &pWInfo->a[i];
    codeOneLoopExplain(pParse, pTabList, pLevel, i, pLevel->iFrom, wctrlFlags);

    notReady = codeOneLoopStart(pWInfo, i, wctrlFlags, notReady);
    pWInfo->iContinue = pLevel->addrCont;
  }

#ifdef SQLITE_TEST  /* For testing and debugging use only */
  /* Record in the query plan information about the current table
  ** and the index used to access it (if any).  If the table itself
  ** is not used, its name is just '{}'.  If no index is used
  ** the index is listed as "{}".  If the primary key is used the

# eqp-4.*:        Compound select statements.
#

proc do_eqp_test {name sql res} {
  set res [list {*}$res]
  uplevel do_execsql_test $name [list "EXPLAIN QUERY PLAN $sql"] [list $res]
}
proc det {args} { uplevel do_eqp_test $args }

do_execsql_test 1.1 {
  CREATE TABLE t1(a, b);
  CREATE INDEX i1 ON t1(a);
  CREATE INDEX i2 ON t1(b);
  CREATE TABLE t2(a, b);
  CREATE TABLE t3(a, b);
}

do_eqp_test 1.2 {
  SELECT * FROM t2, t1 WHERE t1.a=1 OR t1.b=2;
} {
  0 0 1 {SCAN TABLE t1 BY INDEX i1 (a=?) (~10 rows)} 
  0 0 1 {SCAN TABLE t1 BY INDEX i2 (b=?) (~10 rows)} 
  0 1 0 {SCAN TABLE t2 (~1000000 rows)}
}
do_eqp_test 1.3 {
  SELECT * FROM t2 CROSS JOIN t1 WHERE t1.a=1 OR t1.b=2;
} {
  0 0 0 {SCAN TABLE t2 (~1000000 rows)}
  0 1 1 {SCAN TABLE t1 BY INDEX i1 (a=?) (~10 rows)} 
  0 1 1 {SCAN TABLE t1 BY INDEX i2 (b=?) (~10 rows)} 
}
do_eqp_test 1.3 {
  SELECT a FROM t1 ORDER BY a
} {
  0 0 0 {SCAN TABLE t1 BY COVERING INDEX i1 (~1000000 rows)}
}
do_eqp_test 1.4 {
  SELECT a FROM t1 ORDER BY +a
} {
  0 0 0 {SCAN TABLE t1 (~1000000 rows)}
  0 0 0 {USE TEMP B-TREE FOR ORDER BY}
}
do_eqp_test 1.5 {
  SELECT a FROM t1 WHERE a=4
} {
  0 0 0 {SCAN TABLE t1 BY COVERING INDEX i1 (a=?) (~10 rows)}
}
do_eqp_test 1.6 {
  SELECT DISTINCT count(*) FROM t3 GROUP BY a;
} {
  0 0 0 {SCAN TABLE t3 (~1000000 rows)}
  0 0 0 {USE TEMP B-TREE FOR GROUP BY}
  0 0 0 {USE TEMP B-TREE FOR DISTINCT}
}

#-------------------------------------------------------------------------
# Test cases eqp-2.* - tests for single select statements.
#
drop_all_tables
do_execsql_test 2.1 {
  CREATE TABLE t1(x, y);

  CREATE TABLE t2(x, y);
  CREATE INDEX t2i1 ON t2(x);
}


det 2.2.1 "SELECT DISTINCT min(x), max(x) FROM t1 GROUP BY x ORDER BY 1" {

  0 0 0 {SCAN TABLE t1 (~1000000 rows)}
  0 0 0 {USE TEMP B-TREE FOR GROUP BY}
  0 0 0 {USE TEMP B-TREE FOR DISTINCT}
  0 0 0 {USE TEMP B-TREE FOR ORDER BY}
}
det 2.2.2 "SELECT DISTINCT min(x), max(x) FROM t2 GROUP BY x ORDER BY 1" {
  0 0 0 {SCAN TABLE t2 BY COVERING INDEX t2i1 (~1000000 rows)}
  0 0 0 {USE TEMP B-TREE FOR DISTINCT}
  0 0 0 {USE TEMP B-TREE FOR ORDER BY}
}
det 2.2.3 "SELECT DISTINCT * FROM t1" {
  0 0 0 {SCAN TABLE t1 (~1000000 rows)}
  0 0 0 {USE TEMP B-TREE FOR DISTINCT}
}
det 2.2.4 "SELECT DISTINCT * FROM t1, t2" {
  0 0 0 {SCAN TABLE t1 (~1000000 rows)}
  0 1 1 {SCAN TABLE t2 (~1000000 rows)}
  0 0 0 {USE TEMP B-TREE FOR DISTINCT}
}
det 2.2.5 "SELECT DISTINCT * FROM t1, t2 ORDER BY t1.x" {
  0 0 0 {SCAN TABLE t1 (~1000000 rows)}
  0 1 1 {SCAN TABLE t2 (~1000000 rows)}
  0 0 0 {USE TEMP B-TREE FOR DISTINCT}
  0 0 0 {USE TEMP B-TREE FOR ORDER BY}
}
det 2.2.6 "SELECT DISTINCT t2.x FROM t1, t2 ORDER BY t2.x" {
  0 0 1 {SCAN TABLE t2 BY COVERING INDEX t2i1 (~1000000 rows)}
  0 1 0 {SCAN TABLE t1 (~1000000 rows)}
}

det 2.3.1 "SELECT max(x) FROM t2" {
  0 0 0 {SCAN TABLE t2 BY COVERING INDEX t2i1 (~1 rows)}
}
det 2.3.2 "SELECT min(x) FROM t2" {
  0 0 0 {SCAN TABLE t2 BY COVERING INDEX t2i1 (~1 rows)}
}
det 2.3.3 "SELECT min(x), max(x) FROM t2" {
  0 0 0 {SCAN TABLE t2 (~1000000 rows)}
}

det 2.4.1 "SELECT * FROM t1 WHERE rowid=?" {
  0 0 0 {SCAN TABLE t1 BY INTEGER PRIMARY KEY (rowid=?) (~1 rows)}
}



#-------------------------------------------------------------------------
# Test cases eqp-3.* - tests for select statements that use sub-selects.
#
do_eqp_test 3.1.1 {
  SELECT (SELECT x FROM t1 AS sub) FROM t1;
} {
  0 0 0 {SCAN TABLE t1 (~1000000 rows)}
  0 0 0 {EXECUTE SCALAR SUBQUERY 1}
  1 0 0 {SCAN TABLE t1 AS sub (~1000000 rows)}
}
do_eqp_test 3.1.2 {
  SELECT * FROM t1 WHERE (SELECT x FROM t1 AS sub);
} {
  0 0 0 {SCAN TABLE t1 (~1000000 rows)}
  0 0 0 {EXECUTE SCALAR SUBQUERY 1}
  1 0 0 {SCAN TABLE t1 AS sub (~1000000 rows)}
}
do_eqp_test 3.1.3 {
  SELECT * FROM t1 WHERE (SELECT x FROM t1 AS sub ORDER BY y);
} {
  0 0 0 {SCAN TABLE t1 (~1000000 rows)}
  0 0 0 {EXECUTE SCALAR SUBQUERY 1}
  1 0 0 {SCAN TABLE t1 AS sub (~1000000 rows)}
  1 0 0 {USE TEMP B-TREE FOR ORDER BY}
}
do_eqp_test 3.1.4 {
  SELECT * FROM t1 WHERE (SELECT x FROM t2 ORDER BY x);
} {
  0 0 0 {SCAN TABLE t1 (~1000000 rows)}
  0 0 0 {EXECUTE SCALAR SUBQUERY 1}
  1 0 0 {SCAN TABLE t2 BY COVERING INDEX t2i1 (~1000000 rows)}
}

det 3.2.1 {
  SELECT * FROM (SELECT * FROM t1 ORDER BY x LIMIT 10) ORDER BY y LIMIT 5
} {
  1 0 0 {SCAN TABLE t1 (~1000000 rows)} 
  1 0 0 {USE TEMP B-TREE FOR ORDER BY} 
  0 0 0 {SCAN SUBQUERY 1 (~1000000 rows)} 
  0 0 0 {USE TEMP B-TREE FOR ORDER BY}
}
det 3.2.2 {
  SELECT * FROM 
    (SELECT * FROM t1 ORDER BY x LIMIT 10) AS x1,
    (SELECT * FROM t2 ORDER BY x LIMIT 10) AS x2
  ORDER BY x2.y LIMIT 5
} {
  1 0 0 {SCAN TABLE t1 (~1000000 rows)} 
  1 0 0 {USE TEMP B-TREE FOR ORDER BY} 
  2 0 0 {SCAN TABLE t2 BY INDEX t2i1 (~1000000 rows)} 
  0 0 0 {SCAN SUBQUERY 1 AS x1 (~1000000 rows)} 
  0 1 1 {SCAN SUBQUERY 2 AS x2 (~1000000 rows)} 
  0 0 0 {USE TEMP B-TREE FOR ORDER BY}
}

#-------------------------------------------------------------------------
# Test cases eqp-4.* - tests for composite select statements.
#
do_eqp_test 4.1.1 {
  SELECT * FROM t1 UNION ALL SELECT * FROM t2
} {
  1 0 0 {SCAN TABLE t1 (~1000000 rows)} 
  2 0 0 {SCAN TABLE t2 (~1000000 rows)} 
}
do_eqp_test 4.1.2 {
  SELECT * FROM t1 UNION ALL SELECT * FROM t2 ORDER BY 2
} {
  1 0 0 {SCAN TABLE t1 (~1000000 rows)} 
  1 0 0 {USE TEMP B-TREE FOR ORDER BY}
  2 0 0 {SCAN TABLE t2 (~1000000 rows)} 
  2 0 0 {USE TEMP B-TREE FOR ORDER BY}
}
do_eqp_test 4.1.3 {
  SELECT * FROM t1 UNION SELECT * FROM t2 ORDER BY 2
} {
  1 0 0 {SCAN TABLE t1 (~1000000 rows)} 
  1 0 0 {USE TEMP B-TREE FOR ORDER BY}
  2 0 0 {SCAN TABLE t2 (~1000000 rows)} 
  2 0 0 {USE TEMP B-TREE FOR ORDER BY}
}
do_eqp_test 4.1.4 {
  SELECT * FROM t1 INTERSECT SELECT * FROM t2 ORDER BY 2
} {
  1 0 0 {SCAN TABLE t1 (~1000000 rows)} 
  1 0 0 {USE TEMP B-TREE FOR ORDER BY}
  2 0 0 {SCAN TABLE t2 (~1000000 rows)} 
  2 0 0 {USE TEMP B-TREE FOR ORDER BY}
}
do_eqp_test 4.1.5 {
  SELECT * FROM t1 EXCEPT SELECT * FROM t2 ORDER BY 2
} {
  1 0 0 {SCAN TABLE t1 (~1000000 rows)} 
  1 0 0 {USE TEMP B-TREE FOR ORDER BY}
  2 0 0 {SCAN TABLE t2 (~1000000 rows)} 
  2 0 0 {USE TEMP B-TREE FOR ORDER BY}
}

do_eqp_test 4.2.2 {
  SELECT * FROM t1 UNION ALL SELECT * FROM t2 ORDER BY 1
} {
  1 0 0 {SCAN TABLE t1 (~1000000 rows)} 
  1 0 0 {USE TEMP B-TREE FOR ORDER BY}
  2 0 0 {SCAN TABLE t2 BY INDEX t2i1 (~1000000 rows)} 
}


do_eqp_test 4.2.3 {
  SELECT * FROM t1 UNION SELECT * FROM t2 ORDER BY 1
} {
  1 0 0 {SCAN TABLE t1 (~1000000 rows)} 
  1 0 0 {USE TEMP B-TREE FOR ORDER BY}
  2 0 0 {SCAN TABLE t2 (~1000000 rows)} 
  2 0 0 {USE TEMP B-TREE FOR ORDER BY}
}
do_eqp_test 4.2.4 {
  SELECT * FROM t1 INTERSECT SELECT * FROM t2 ORDER BY 1
} {
  1 0 0 {SCAN TABLE t1 (~1000000 rows)} 
  1 0 0 {USE TEMP B-TREE FOR ORDER BY}
  2 0 0 {SCAN TABLE t2 (~1000000 rows)} 
  2 0 0 {USE TEMP B-TREE FOR ORDER BY}
}
do_eqp_test 4.2.5 {
  SELECT * FROM t1 EXCEPT SELECT * FROM t2 ORDER BY 1
} {
  1 0 0 {SCAN TABLE t1 (~1000000 rows)} 
  1 0 0 {USE TEMP B-TREE FOR ORDER BY}
  2 0 0 {SCAN TABLE t2 (~1000000 rows)} 
  2 0 0 {USE TEMP B-TREE FOR ORDER BY}
}

do_eqp_test 4.3.1 {
  SELECT x FROM t1 UNION SELECT x FROM t2
} {
  1 0 0 {SCAN TABLE t1 (~1000000 rows)} 
  2 0 0 {SCAN TABLE t2 (~1000000 rows)} 
}

finish_test