create_unique_plan() should not discard existing output columns of the
subplan it starts with, as they may be needed at upper join levels. See comments added to code for the non-obvious reason why. Per bug report from Robert Creager.
This commit is contained in:
Tom Lane
parent
d862045dfc
commit
ecbed6e1b9
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@ -10,7 +10,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.151 2003/08/04 02:40:00 momjian Exp $
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* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.152 2003/08/07 19:20:22 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -504,52 +504,87 @@ create_unique_plan(Query *root, UniquePath * best_path)
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{
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Plan *plan;
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Plan *subplan;
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List *sub_targetlist;
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List *uniq_exprs;
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int numGroupCols;
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AttrNumber *groupColIdx;
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int groupColPos;
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List *newtlist;
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int nextresno;
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bool newitems;
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List *my_tlist;
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List *l;
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subplan = create_plan(root, best_path->subpath);
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/*
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* If the subplan came from an IN subselect (currently always the
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* case), we need to instantiate the correct output targetlist for the
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* subselect, rather than using the flattened tlist.
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* As constructed, the subplan has a "flat" tlist containing just the
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* Vars needed here and at upper levels. The values we are supposed
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* to unique-ify may be expressions in these variables. We have to
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* add any such expressions to the subplan's tlist. We then build
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* control information showing which subplan output columns are to be
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* examined by the grouping step. (Since we do not remove any existing
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* subplan outputs, not all the output columns may be used for grouping.)
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*
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* Note: the reason we don't remove any subplan outputs is that there
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* are scenarios where a Var is needed at higher levels even though it
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* is not one of the nominal outputs of an IN clause. Consider
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* WHERE x IN (SELECT y FROM t1,t2 WHERE y = z)
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* Implied equality deduction will generate an "x = z" clause, which may
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* get used instead of "x = y" in the upper join step. Therefore the
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* sub-select had better deliver both y and z in its targetlist. It is
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* sufficient to unique-ify on y, however.
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*
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* To find the correct list of values to unique-ify, we look in the
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* information saved for IN expressions. If this code is ever used in
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* other scenarios, some other way of finding what to unique-ify will
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* be needed.
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*/
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sub_targetlist = NIL;
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uniq_exprs = NIL; /* just to keep compiler quiet */
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foreach(l, root->in_info_list)
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{
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InClauseInfo *ininfo = (InClauseInfo *) lfirst(l);
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if (bms_equal(ininfo->righthand, best_path->path.parent->relids))
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{
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sub_targetlist = ininfo->sub_targetlist;
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uniq_exprs = ininfo->sub_targetlist;
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break;
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}
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}
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if (l == NIL) /* fell out of loop? */
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elog(ERROR, "could not find UniquePath in in_info_list");
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if (sub_targetlist)
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/* set up to record positions of unique columns */
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numGroupCols = length(uniq_exprs);
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groupColIdx = (AttrNumber *) palloc(numGroupCols * sizeof(AttrNumber));
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groupColPos = 0;
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/* not sure if tlist might be shared with other nodes, so copy */
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newtlist = copyObject(subplan->targetlist);
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nextresno = length(newtlist) + 1;
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newitems = false;
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foreach(l, uniq_exprs)
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{
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/*
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* Transform list of plain Vars into targetlist
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*/
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List *newtlist = NIL;
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int resno = 1;
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Node *uniqexpr = lfirst(l);
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TargetEntry *tle;
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foreach(l, sub_targetlist)
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tle = tlistentry_member(uniqexpr, newtlist);
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if (!tle)
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{
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Node *tlexpr = lfirst(l);
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TargetEntry *tle;
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tle = makeTargetEntry(makeResdom(resno,
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exprType(tlexpr),
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exprTypmod(tlexpr),
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tle = makeTargetEntry(makeResdom(nextresno,
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exprType(uniqexpr),
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exprTypmod(uniqexpr),
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NULL,
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false),
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(Expr *) tlexpr);
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(Expr *) uniqexpr);
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newtlist = lappend(newtlist, tle);
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resno++;
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nextresno++;
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newitems = true;
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}
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groupColIdx[groupColPos++] = tle->resdom->resno;
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}
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if (newitems)
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{
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/*
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* If the top plan node can't do projections, we need to add a
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* Result node to help it along.
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@ -563,21 +598,15 @@ create_unique_plan(Query *root, UniquePath * best_path)
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subplan->targetlist = newtlist;
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}
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/* Copy tlist again to make one we can put sorting labels on */
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my_tlist = copyObject(subplan->targetlist);
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if (best_path->use_hash)
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{
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int numGroupCols = length(my_tlist);
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long numGroups;
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AttrNumber *groupColIdx;
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int i;
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numGroups = (long) Min(best_path->rows, (double) LONG_MAX);
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groupColIdx = (AttrNumber *) palloc(numGroupCols * sizeof(AttrNumber));
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for (i = 0; i < numGroupCols; i++)
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groupColIdx[i] = i + 1;
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plan = (Plan *) make_agg(root,
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my_tlist,
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NIL,
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@ -590,9 +619,17 @@ create_unique_plan(Query *root, UniquePath * best_path)
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}
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else
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{
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List *sortList;
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List *sortList = NIL;
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sortList = addAllTargetsToSortList(NULL, NIL, my_tlist, false);
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for (groupColPos = 0; groupColPos < numGroupCols; groupColPos++)
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{
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TargetEntry *tle;
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tle = nth(groupColIdx[groupColPos] - 1, my_tlist);
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Assert(tle->resdom->resno == groupColIdx[groupColPos]);
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sortList = addTargetToSortList(NULL, tle, sortList,
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my_tlist, NIL, false);
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}
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plan = (Plan *) make_sort_from_sortclauses(root, my_tlist,
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subplan, sortList);
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plan = (Plan *) make_unique(my_tlist, plan, sortList);
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/parser/parse_clause.c,v 1.120 2003/08/04 02:40:01 momjian Exp $
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* $Header: /cvsroot/pgsql/src/backend/parser/parse_clause.c,v 1.121 2003/08/07 19:20:22 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -59,9 +59,6 @@ static Node *buildMergedJoinVar(ParseState *pstate, JoinType jointype,
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Var *l_colvar, Var *r_colvar);
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static TargetEntry *findTargetlistEntry(ParseState *pstate, Node *node,
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List *tlist, int clause);
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static List *addTargetToSortList(ParseState *pstate, TargetEntry *tle,
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List *sortlist, List *targetlist,
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List *opname, bool resolveUnknown);
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/*
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@ -1478,7 +1475,7 @@ addAllTargetsToSortList(ParseState *pstate, List *sortlist,
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*
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* Returns the updated ORDER BY list.
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*/
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static List *
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List *
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addTargetToSortList(ParseState *pstate, TargetEntry *tle,
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List *sortlist, List *targetlist,
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List *opname, bool resolveUnknown)
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@ -7,7 +7,7 @@
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* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $Id: parse_clause.h,v 1.35 2003/08/04 02:40:14 momjian Exp $
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* $Id: parse_clause.h,v 1.36 2003/08/07 19:20:23 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -35,6 +35,9 @@ extern List *transformDistinctClause(ParseState *pstate, List *distinctlist,
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extern List *addAllTargetsToSortList(ParseState *pstate,
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List *sortlist, List *targetlist,
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bool resolveUnknown);
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extern List *addTargetToSortList(ParseState *pstate, TargetEntry *tle,
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List *sortlist, List *targetlist,
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List *opname, bool resolveUnknown);
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extern Index assignSortGroupRef(TargetEntry *tle, List *tlist);
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extern bool targetIsInSortList(TargetEntry *tle, List *sortList);
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@ -2127,6 +2127,18 @@ on (x1 = xx1) where (xx2 is not null);
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4 | 44 | 4 | | 4 | 44
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(3 rows)
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--
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-- regression test: check for bug with propagation of implied equality
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-- to outside an IN
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--
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select count(*) from tenk1 a where unique1 in
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(select unique1 from tenk1 b join tenk1 c using (unique1)
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where b.unique2 = 42);
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count
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-------
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1
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(1 row)
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--
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-- Clean up
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--
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@ -330,6 +330,14 @@ on (x1 = xx1) where (y2 is not null);
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select * from (x left join y on (x1 = y1)) left join x xx(xx1,xx2)
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on (x1 = xx1) where (xx2 is not null);
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--
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-- regression test: check for bug with propagation of implied equality
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-- to outside an IN
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--
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select count(*) from tenk1 a where unique1 in
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(select unique1 from tenk1 b join tenk1 c using (unique1)
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where b.unique2 = 42);
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--
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-- Clean up
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