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Fix plan created for inherited UPDATE/DELETE with all tables excluded.

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In the case where inheritance_planner() finds that every table has
been excluded by constraints, it thought it could get away with
making a plan consisting of just a dummy Result node.  While certainly
there's no updating or deleting to be done, this had two user-visible
problems: the plan did not report the correct set of output columns
when a RETURNING clause was present, and if there were any
statement-level triggers that should be fired, it didn't fire them.

Hence, rather than only generating the dummy Result, we need to
stick a valid ModifyTable node on top, which requires a tad more
effort here.

It's been broken this way for as long as inheritance_planner() has
known about deleting excluded subplans at all (cf commit 635d42e9c),
so back-patch to all supported branches.

Amit Langote and Tom Lane, per a report from Petr Fedorov.

Discussion: https://postgr.es/m/5da6f0f0-1364-1876-6978-907678f89a3e@phystech.edu
This commit is contained in:
Tom Lane
2019-02-22 12:23:00 -05:00
parent 630de1131d
commit 07fba9ad9b
5 changed files with 164 additions and 23 deletions
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70
src/backend/optimizer/plan/planner.c
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@ -1570,34 +1570,58 @@ inheritance_planner(PlannerInfo *root)
* to get control here.
*/
/*
* If we managed to exclude every child rel, return a dummy plan; it
* doesn't even need a ModifyTable node.
*/
if (subpaths == NIL)
{
set_dummy_rel_pathlist(final_rel);
return;
/*
* We managed to exclude every child rel, so generate a dummy path
* representing the empty set. Although it's clear that no data will
* be updated or deleted, we will still need to have a ModifyTable
* node so that any statement triggers are executed. (This could be
* cleaner if we fixed nodeModifyTable.c to support zero child nodes,
* but that probably wouldn't be a net win.)
*/
List *tlist;
Path *dummy_path;
/* tlist processing never got done, either */
tlist = root->processed_tlist = preprocess_targetlist(root);
final_rel->reltarget = create_pathtarget(root, tlist);
/* Make a dummy path, cf set_dummy_rel_pathlist() */
dummy_path = (Path *) create_append_path(NULL, final_rel, NIL, NIL,
NULL, 0, false, NIL, -1);
/* These lists must be nonempty to make a valid ModifyTable node */
subpaths = list_make1(dummy_path);
subroots = list_make1(root);
resultRelations = list_make1_int(parse->resultRelation);
if (parse->withCheckOptions)
withCheckOptionLists = list_make1(parse->withCheckOptions);
if (parse->returningList)
returningLists = list_make1(parse->returningList);
}
/*
* Put back the final adjusted rtable into the master copy of the Query.
* (We mustn't do this if we found no non-excluded children.)
*/
parse->rtable = final_rtable;
root->simple_rel_array_size = save_rel_array_size;
root->simple_rel_array = save_rel_array;
root->append_rel_array = save_append_rel_array;
/* Must reconstruct master's simple_rte_array, too */
root->simple_rte_array = (RangeTblEntry **)
palloc0((list_length(final_rtable) + 1) * sizeof(RangeTblEntry *));
rti = 1;
foreach(lc, final_rtable)
else
{
RangeTblEntry *rte = lfirst_node(RangeTblEntry, lc);
/*
* Put back the final adjusted rtable into the master copy of the
* Query. (We mustn't do this if we found no non-excluded children,
* since we never saved an adjusted rtable at all.)
*/
parse->rtable = final_rtable;
root->simple_rel_array_size = save_rel_array_size;
root->simple_rel_array = save_rel_array;
root->append_rel_array = save_append_rel_array;
root->simple_rte_array[rti++] = rte;
/* Must reconstruct master's simple_rte_array, too */
root->simple_rte_array = (RangeTblEntry **)
palloc0((list_length(final_rtable) + 1) * sizeof(RangeTblEntry *));
rti = 1;
foreach(lc, final_rtable)
{
RangeTblEntry *rte = lfirst_node(RangeTblEntry, lc);
root->simple_rte_array[rti++] = rte;
}
}
/*