diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/optimizer/prep/prepjointree.c | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/src/backend/optimizer/prep/prepjointree.c b/src/backend/optimizer/prep/prepjointree.c index 62a16687963..99ac3351146 100644 --- a/src/backend/optimizer/prep/prepjointree.c +++ b/src/backend/optimizer/prep/prepjointree.c @@ -893,10 +893,9 @@ pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte, ListCell *lc; /* - * Need a modifiable copy of the subquery to hack on. Even if we didn't - * sometimes choose not to pull up below, we must do this to avoid - * problems if the same subquery is referenced from multiple jointree - * items (which can't happen normally, but might after rule rewriting). + * Make a modifiable copy of the subquery to hack on, so that the RTE will + * be left unchanged in case we decide below that we can't pull it up + * after all. */ subquery = copyObject(rte->subquery); @@ -1175,6 +1174,14 @@ pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte, Assert(subroot->placeholder_list == NIL); /* + * We no longer need the RTE's copy of the subquery's query tree. Getting + * rid of it saves nothing in particular so far as this level of query is + * concerned; but if this query level is in turn pulled up into a parent, + * we'd waste cycles copying the now-unused query tree. + */ + rte->subquery = NULL; + + /* * Miscellaneous housekeeping. * * Although replace_rte_variables() faithfully updated parse->hasSubLinks |