On Wed, Feb 27, 2019 at 03:48:08PM -0300, Alvaro Herrera wrote: > I just happened to come across the result of this rationale in > pg_partition_tree() (an SRF) while developing a new related function, > pg_partition_ancestors(), and find the resulting behavior rather absurd > -- it returns one row with all NULL columns, rather than no rows. I > think the sensible behavior would be to do SRF_RETURN_DONE() before > stashing any rows to the output, so that we get an empty result set > instead.
Hmm. Going through the thread again NULL was decided to make the whole experience consistent, now by returning nothing we would get a behavior as consistent as when NULL is used in input, so point taken to tune the behavior for unsupported relkinds and undefined objects. Does the attached look fine to you? -- Michael
diff --git a/src/backend/utils/adt/partitionfuncs.c b/src/backend/utils/adt/partitionfuncs.c
index ffd66b6439..36d9f69cbc 100644
--- a/src/backend/utils/adt/partitionfuncs.c
+++ b/src/backend/utils/adt/partitionfuncs.c
@@ -69,9 +69,6 @@ pg_partition_tree(PG_FUNCTION_ARGS)
FuncCallContext *funcctx;
ListCell **next;
- if (!check_rel_can_be_partition(rootrelid))
- PG_RETURN_NULL();
-
/* stuff done only on the first call of the function */
if (SRF_IS_FIRSTCALL())
{
@@ -82,6 +79,9 @@ pg_partition_tree(PG_FUNCTION_ARGS)
/* create a function context for cross-call persistence */
funcctx = SRF_FIRSTCALL_INIT();
+ if (!check_rel_can_be_partition(rootrelid))
+ SRF_RETURN_DONE(funcctx);
+
/* switch to memory context appropriate for multiple function calls */
oldcxt = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
diff --git a/src/test/regress/expected/partition_info.out b/src/test/regress/expected/partition_info.out
index a884df976f..73269ffd09 100644
--- a/src/test/regress/expected/partition_info.out
+++ b/src/test/regress/expected/partition_info.out
@@ -9,8 +9,7 @@ SELECT * FROM pg_partition_tree(NULL);
SELECT * FROM pg_partition_tree(0);
relid | parentrelid | isleaf | level
-------+-------------+--------+-------
- | | |
-(1 row)
+(0 rows)
SELECT pg_partition_root(NULL);
pg_partition_root
@@ -163,14 +162,12 @@ CREATE MATERIALIZED VIEW ptif_test_matview AS SELECT 1;
SELECT * FROM pg_partition_tree('ptif_test_view');
relid | parentrelid | isleaf | level
-------+-------------+--------+-------
- | | |
-(1 row)
+(0 rows)
SELECT * FROM pg_partition_tree('ptif_test_matview');
relid | parentrelid | isleaf | level
-------+-------------+--------+-------
- | | |
-(1 row)
+(0 rows)
SELECT pg_partition_root('ptif_test_view');
pg_partition_root
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