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Diffstat (limited to 'src/backend/optimizer/util/pathnode.c')
| -rw-r--r-- | src/backend/optimizer/util/pathnode.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/src/backend/optimizer/util/pathnode.c b/src/backend/optimizer/util/pathnode.c index 0652a2d3598..2c1c46434d5 100644 --- a/src/backend/optimizer/util/pathnode.c +++ b/src/backend/optimizer/util/pathnode.c @@ -1474,6 +1474,17 @@ query_is_distinct_for(Query *query, List *colnos, List *opids) Assert(list_length(colnos) == list_length(opids)); /* + * A set-returning function in the query's targetlist can result in + * returning duplicate rows, if the SRF is evaluated after the + * de-duplication step; so we play it safe and say "no" if there are any + * SRFs. (We could be certain that it's okay if SRFs appear only in the + * specified columns, since those must be evaluated before de-duplication; + * but it doesn't presently seem worth the complication to check that.) + */ + if (expression_returns_set((Node *) query->targetList)) + return false; + + /* * DISTINCT (including DISTINCT ON) guarantees uniqueness if all the * columns in the DISTINCT clause appear in colnos and operator semantics * match. |