mirror of https://github.com/postgres/postgres
Previous patch to mark UNION outputs with common typmod (if any) breaks
three-or-more-way UNIONs, as per example from Josh Berkus. Cause is a fragile assumption that one tlist's entries will exactly match another. Restructure code to make that assumption a little less fragile.
This commit is contained in:
Tom Lane
parent
17b6baf17d
commit
944671820f
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@ -14,7 +14,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepunion.c,v 1.70 2002/03/01 06:01:20 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepunion.c,v 1.71 2002/03/05 05:10:24 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -63,7 +63,9 @@ static List *generate_setop_tlist(List *colTypes, int flag,
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bool hack_constants,
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List *input_tlist,
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List *refnames_tlist);
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static void merge_tlist_typmods(List *tlist, List *planlist);
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static List *generate_append_tlist(List *colTypes, bool flag,
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List *input_plans,
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List *refnames_tlist);
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static bool tlist_same_datatypes(List *tlist, List *colTypes, bool junkOK);
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static Node *adjust_inherited_attrs_mutator(Node *node,
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adjust_inherited_attrs_context *context);
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@ -169,13 +171,11 @@ recurse_set_operations(Node *setOp, Query *parse,
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*
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* XXX you don't really want to know about this: setrefs.c will apply
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* replace_vars_with_subplan_refs() to the Result node's tlist.
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* This would fail if the input plan's non-resjunk tlist entries
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* were not all simple Vars equal() to the referencing Vars
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* generated by generate_setop_tlist(). However, since the input
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* plan was generated by generate_union_plan() or
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* generate_nonunion_plan(), the referencing Vars will equal the
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* tlist entries they reference. Ugly but I don't feel like making
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* that code more general right now.
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* This would fail if the Vars generated by generate_setop_tlist()
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* were not exactly equal() to the corresponding tlist entries of
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* the subplan. However, since the subplan was generated by
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* generate_union_plan() or generate_nonunion_plan(), and hence its
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* tlist was generated by generate_append_tlist(), this will work.
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*/
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if (flag >= 0 ||
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!tlist_same_datatypes(plan->targetlist, colTypes, junkOK))
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@ -226,10 +226,8 @@ generate_union_plan(SetOperationStmt *op, Query *parse,
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* concerned, but we must make it look real anyway for the benefit of
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* the next plan level up.
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*/
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tlist = generate_setop_tlist(op->colTypes, -1, false,
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((Plan *) lfirst(planlist))->targetlist,
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refnames_tlist);
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merge_tlist_typmods(tlist, planlist);
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tlist = generate_append_tlist(op->colTypes, false,
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planlist, refnames_tlist);
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/*
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* Append the child results together.
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@ -285,10 +283,8 @@ generate_nonunion_plan(SetOperationStmt *op, Query *parse,
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* flag column is shown as a variable not a constant, else setrefs.c
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* will get confused.
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*/
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tlist = generate_setop_tlist(op->colTypes, 2, false,
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lplan->targetlist,
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refnames_tlist);
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merge_tlist_typmods(tlist, planlist);
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tlist = generate_append_tlist(op->colTypes, true,
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planlist, refnames_tlist);
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/*
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* Append the child results together.
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@ -368,8 +364,7 @@ recurse_union_children(Node *setOp, Query *parse,
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* Generate targetlist for a set-operation plan node
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*
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* colTypes: column datatypes for non-junk columns
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* flag: -1 if no flag column needed, 0 or 1 to create a const flag column,
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* 2 to create a variable flag column
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* flag: -1 if no flag column needed, 0 or 1 to create a const flag column
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* hack_constants: true to copy up constants (see comments in code)
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* input_tlist: targetlist of this node's input node
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* refnames_tlist: targetlist to take column names from
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@ -450,26 +445,14 @@ generate_setop_tlist(List *colTypes, int flag,
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-1,
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pstrdup("flag"),
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true);
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if (flag <= 1)
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{
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/* flag value is the given constant */
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expr = (Node *) makeConst(INT4OID,
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sizeof(int4),
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Int32GetDatum(flag),
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false,
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true,
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false,
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false);
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}
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else
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{
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/* flag value is being copied up from subplan */
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expr = (Node *) makeVar(0,
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resdom->resno,
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INT4OID,
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-1,
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0);
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}
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/* flag value is the given constant */
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expr = (Node *) makeConst(INT4OID,
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sizeof(int4),
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Int32GetDatum(flag),
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false,
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true,
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false,
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false);
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tlist = lappend(tlist, makeTargetEntry(resdom, expr));
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}
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@ -477,44 +460,117 @@ generate_setop_tlist(List *colTypes, int flag,
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}
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/*
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* Merge typmods of a list of set-operation subplans.
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* Generate targetlist for a set-operation Append node
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*
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* If the inputs all agree on type and typmod of a particular column,
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* use that typmod; else use -1. We assume the result tlist has been
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* initialized with the types and typmods of the first input subplan.
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* colTypes: column datatypes for non-junk columns
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* flag: true to create a flag column copied up from subplans
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* input_plans: list of sub-plans of the Append
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* refnames_tlist: targetlist to take column names from
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*
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* The entries in the Append's targetlist should always be simple Vars;
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* we just have to make sure they have the right datatypes and typmods.
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*/
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static void
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merge_tlist_typmods(List *tlist, List *planlist)
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static List *
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generate_append_tlist(List *colTypes, bool flag,
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List *input_plans,
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List *refnames_tlist)
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{
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List *tlist = NIL;
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int resno = 1;
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List *curColType;
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int colindex;
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Resdom *resdom;
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Node *expr;
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List *planl;
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int32 *colTypmods;
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foreach(planl, planlist)
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/*
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* First extract typmods to use.
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*
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* If the inputs all agree on type and typmod of a particular column,
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* use that typmod; else use -1.
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*/
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colTypmods = (int32 *) palloc(length(colTypes) * sizeof(int32));
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foreach(planl, input_plans)
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{
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Plan *subplan = (Plan *) lfirst(planl);
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List *subtlist = subplan->targetlist;
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List *restlist;
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List *subtlist;
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foreach(restlist, tlist)
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curColType = colTypes;
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colindex = 0;
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foreach(subtlist, subplan->targetlist)
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{
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TargetEntry *restle = (TargetEntry *) lfirst(restlist);
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TargetEntry *subtle;
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TargetEntry *subtle = (TargetEntry *) lfirst(subtlist);
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if (restle->resdom->resjunk)
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if (subtle->resdom->resjunk)
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continue;
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Assert(subtlist != NIL);
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subtle = (TargetEntry *) lfirst(subtlist);
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while (subtle->resdom->resjunk)
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Assert(curColType != NIL);
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if (subtle->resdom->restype == (Oid) lfirsti(curColType))
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{
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subtlist = lnext(subtlist);
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Assert(subtlist != NIL);
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subtle = (TargetEntry *) lfirst(subtlist);
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/* If first subplan, copy the typmod; else compare */
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if (planl == input_plans)
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colTypmods[colindex] = subtle->resdom->restypmod;
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else if (subtle->resdom->restypmod != colTypmods[colindex])
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colTypmods[colindex] = -1;
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}
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if (restle->resdom->restype != subtle->resdom->restype ||
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restle->resdom->restypmod != subtle->resdom->restypmod)
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restle->resdom->restypmod = -1;
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subtlist = lnext(subtlist);
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else
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{
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/* types disagree, so force typmod to -1 */
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colTypmods[colindex] = -1;
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}
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curColType = lnext(curColType);
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colindex++;
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}
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Assert(curColType == NIL);
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}
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/*
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* Now we can build the tlist for the Append.
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*/
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colindex = 0;
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foreach(curColType, colTypes)
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{
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Oid colType = (Oid) lfirsti(curColType);
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int32 colTypmod = colTypmods[colindex++];
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TargetEntry *reftle = (TargetEntry *) lfirst(refnames_tlist);
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Assert(reftle->resdom->resno == resno);
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Assert(!reftle->resdom->resjunk);
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expr = (Node *) makeVar(0,
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resno,
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colType,
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colTypmod,
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0);
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resdom = makeResdom((AttrNumber) resno++,
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colType,
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colTypmod,
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pstrdup(reftle->resdom->resname),
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false);
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tlist = lappend(tlist, makeTargetEntry(resdom, expr));
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refnames_tlist = lnext(refnames_tlist);
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}
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if (flag)
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{
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/* Add a resjunk flag column */
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resdom = makeResdom((AttrNumber) resno++,
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INT4OID,
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-1,
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pstrdup("flag"),
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true);
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/* flag value is shown as copied up from subplan */
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expr = (Node *) makeVar(0,
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resdom->resno,
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INT4OID,
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-1,
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0);
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tlist = lappend(tlist, makeTargetEntry(resdom, expr));
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}
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pfree(colTypmods);
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return tlist;
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}
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/*
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