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Previous patch to mark UNION outputs with common typmod (if any) breaks

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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.
REL7_2_STABLE
Tom Lane 24 years ago
parent 06b3be1e48
commit 68d813795a
1 changed files with 118 additions and 62 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 164
      src/backend/optimizer/prep/prepunion.c

164
src/backend/optimizer/prep/prepunion.c
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@ -14,7 +14,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepunion.c,v 1.69 2001/11/12 20:04:20 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepunion.c,v 1.69.2.1 2002/03/05 05:13:36 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -63,7 +63,9 @@ static List *generate_setop_tlist(List *colTypes, int flag,
bool hack_constants,
List *input_tlist,
List *refnames_tlist);
static void merge_tlist_typmods(List *tlist, List *planlist);
static List *generate_append_tlist(List *colTypes, bool flag,
List *input_plans,
List *refnames_tlist);
static bool tlist_same_datatypes(List *tlist, List *colTypes, bool junkOK);
static Node *adjust_inherited_attrs_mutator(Node *node,
adjust_inherited_attrs_context *context);
@ -169,13 +171,11 @@ recurse_set_operations(Node *setOp, Query *parse,
*
* XXX you don't really want to know about this: setrefs.c will apply
* replace_vars_with_subplan_refs() to the Result node's tlist.
* This would fail if the input plan's non-resjunk tlist entries
* were not all simple Vars equal() to the referencing Vars
* generated by generate_setop_tlist(). However, since the input
* plan was generated by generate_union_plan() or
* generate_nonunion_plan(), the referencing Vars will equal the
* tlist entries they reference. Ugly but I don't feel like making
* that code more general right now.
* This would fail if the Vars generated by generate_setop_tlist()
* were not exactly equal() to the corresponding tlist entries of
* the subplan. However, since the subplan was generated by
* generate_union_plan() or generate_nonunion_plan(), and hence its
* tlist was generated by generate_append_tlist(), this will work.
*/
if (flag >= 0 ||
!tlist_same_datatypes(plan->targetlist, colTypes, junkOK))
@ -226,10 +226,8 @@ generate_union_plan(SetOperationStmt *op, Query *parse,
* concerned, but we must make it look real anyway for the benefit of
* the next plan level up.
*/
tlist = generate_setop_tlist(op->colTypes, -1, false,
((Plan *) lfirst(planlist))->targetlist,
refnames_tlist);
merge_tlist_typmods(tlist, planlist);
tlist = generate_append_tlist(op->colTypes, false,
planlist, refnames_tlist);
/*
* Append the child results together.
@ -285,10 +283,8 @@ generate_nonunion_plan(SetOperationStmt *op, Query *parse,
* flag column is shown as a variable not a constant, else setrefs.c
* will get confused.
*/
tlist = generate_setop_tlist(op->colTypes, 2, false,
lplan->targetlist,
refnames_tlist);
merge_tlist_typmods(tlist, planlist);
tlist = generate_append_tlist(op->colTypes, true,
planlist, refnames_tlist);
/*
* Append the child results together.
@ -368,8 +364,7 @@ recurse_union_children(Node *setOp, Query *parse,
* Generate targetlist for a set-operation plan node
*
* colTypes: column datatypes for non-junk columns
* flag: -1 if no flag column needed, 0 or 1 to create a const flag column,
* 2 to create a variable flag column
* flag: -1 if no flag column needed, 0 or 1 to create a const flag column
* hack_constants: true to copy up constants (see comments in code)
* input_tlist: targetlist of this node's input node
* refnames_tlist: targetlist to take column names from
@ -450,8 +445,6 @@ generate_setop_tlist(List *colTypes, int flag,
-1,
pstrdup("flag"),
true);
if (flag <= 1)
{
/* flag value is the given constant */
expr = (Node *) makeConst(INT4OID,
sizeof(int4),
@ -460,16 +453,6 @@ generate_setop_tlist(List *colTypes, int flag,
true,
false,
false);
}
else
{
/* flag value is being copied up from subplan */
expr = (Node *) makeVar(0,
resdom->resno,
INT4OID,
-1,
0);
}
tlist = lappend(tlist, makeTargetEntry(resdom, expr));
}
@ -477,44 +460,117 @@ generate_setop_tlist(List *colTypes, int flag,
}
/*
* Merge typmods of a list of set-operation subplans.
* Generate targetlist for a set-operation Append node
*
* If the inputs all agree on type and typmod of a particular column,
* use that typmod; else use -1. We assume the result tlist has been
* initialized with the types and typmods of the first input subplan.
* colTypes: column datatypes for non-junk columns
* flag: true to create a flag column copied up from subplans
* input_plans: list of sub-plans of the Append
* refnames_tlist: targetlist to take column names from
*
* The entries in the Append's targetlist should always be simple Vars;
* we just have to make sure they have the right datatypes and typmods.
*/
static void
merge_tlist_typmods(List *tlist, List *planlist)
static List *
generate_append_tlist(List *colTypes, bool flag,
List *input_plans,
List *refnames_tlist)
{
List *tlist = NIL;
int resno = 1;
List *curColType;
int colindex;
Resdom *resdom;
Node *expr;
List *planl;
int32 *colTypmods;
foreach(planl, planlist)
/*
* First extract typmods to use.
*
* If the inputs all agree on type and typmod of a particular column,
* use that typmod; else use -1.
*/
colTypmods = (int32 *) palloc(length(colTypes) * sizeof(int32));
foreach(planl, input_plans)
{
Plan *subplan = (Plan *) lfirst(planl);
List *subtlist = subplan->targetlist;
List *restlist;
List *subtlist;
foreach(restlist, tlist)
curColType = colTypes;
colindex = 0;
foreach(subtlist, subplan->targetlist)
{
TargetEntry *restle = (TargetEntry *) lfirst(restlist);
TargetEntry *subtle;
TargetEntry *subtle = (TargetEntry *) lfirst(subtlist);
if (restle->resdom->resjunk)
if (subtle->resdom->resjunk)
continue;
Assert(subtlist != NIL);
subtle = (TargetEntry *) lfirst(subtlist);
while (subtle->resdom->resjunk)
Assert(curColType != NIL);
if (subtle->resdom->restype == (Oid) lfirsti(curColType))
{
/* If first subplan, copy the typmod; else compare */
if (planl == input_plans)
colTypmods[colindex] = subtle->resdom->restypmod;
else if (subtle->resdom->restypmod != colTypmods[colindex])
colTypmods[colindex] = -1;
}
else
{
subtlist = lnext(subtlist);
Assert(subtlist != NIL);
subtle = (TargetEntry *) lfirst(subtlist);
/* types disagree, so force typmod to -1 */
colTypmods[colindex] = -1;
}
if (restle->resdom->restype != subtle->resdom->restype ||
restle->resdom->restypmod != subtle->resdom->restypmod)
restle->resdom->restypmod = -1;
subtlist = lnext(subtlist);
curColType = lnext(curColType);
colindex++;
}
Assert(curColType == NIL);
}
/*
* Now we can build the tlist for the Append.
*/
colindex = 0;
foreach(curColType, colTypes)
{
Oid colType = (Oid) lfirsti(curColType);
int32 colTypmod = colTypmods[colindex++];
TargetEntry *reftle = (TargetEntry *) lfirst(refnames_tlist);
Assert(reftle->resdom->resno == resno);
Assert(!reftle->resdom->resjunk);
expr = (Node *) makeVar(0,
resno,
colType,
colTypmod,
0);
resdom = makeResdom((AttrNumber) resno++,
colType,
colTypmod,
pstrdup(reftle->resdom->resname),
false);
tlist = lappend(tlist, makeTargetEntry(resdom, expr));
refnames_tlist = lnext(refnames_tlist);
}
if (flag)
{
/* Add a resjunk flag column */
resdom = makeResdom((AttrNumber) resno++,
INT4OID,
-1,
pstrdup("flag"),
true);
/* flag value is shown as copied up from subplan */
expr = (Node *) makeVar(0,
resdom->resno,
INT4OID,
-1,
0);
tlist = lappend(tlist, makeTargetEntry(resdom, expr));
}
pfree(colTypmods);
return tlist;
}
/*

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