Don't try to parallelize array_agg() on an anonymous record type.

This doesn't work because record_recv requires the typmod that
identifies the specific record type (in our session) and
array_agg_deserialize has no convenient way to get that information.
The result is an "input of anonymous composite types is not
implemented" error.

We could probably make this work if we had to, but it does not seem
worth the trouble, given that it took this long to get a field report.
Just shut off parallelization, as though record_recv didn't exist.

Oversight in commit 16fd03e95.  Back-patch to v16 where that
came in.

Reported-by: Kirill Zdornyy <kirill@dineserve.com>
Diagnosed-by: Richard Guo <guofenglinux@gmail.com>
Author: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: David Rowley <dgrowleyml@gmail.com>
Discussion: https://postgr.es/m/atLI5Kce2ie1zcYjU0w_kjtVaxiYbYGTihrkLDmGZQnRDD4pnXukIATaABbnIj9pUnelC4ESvCXMm4HAyHg-v61XABaKpERj0A2IXzJZM7g=@dineserve.com
Backpatch-through: 16

diff --git a/src/backend/parser/parse_agg.c b/src/backend/parser/parse_agg.c
index b15d9b152ef0f60a152466dcf18b51b5de9469e4..be88909da222d95d4177ae24a06cf39122f60e48 100644 (file)
--- a/src/backend/parser/parse_agg.c
+++ b/src/backend/parser/parse_agg.c
@@ -1961,7 +1961,7 @@ resolve_aggregate_transtype(Oid aggfuncid,
 
 /*
  * agg_args_support_sendreceive
- *     Returns true if all non-byval of aggref's arg types have send and
+ *     Returns true if all non-byval types of aggref's args have send and
  *     receive functions.
  */
 bool
@@ -1976,6 +1976,15 @@ agg_args_support_sendreceive(Aggref *aggref)
        TargetEntry *tle = (TargetEntry *) lfirst(lc);
        Oid         type = exprType((Node *) tle->expr);
 
+       /*
+        * RECORD is a special case: it has typsend/typreceive functions, but
+        * record_recv only works if passed the correct typmod to identify the
+        * specific anonymous record type.  array_agg_deserialize cannot do
+        * that, so we have to disclaim support for the case.
+        */
+       if (type == RECORDOID)
+           return false;
+
        typeTuple = SearchSysCache1(TYPEOID, ObjectIdGetDatum(type));
        if (!HeapTupleIsValid(typeTuple))
            elog(ERROR, "cache lookup failed for type %u", type);

diff --git a/src/test/regress/expected/aggregates.out b/src/test/regress/expected/aggregates.out
index 1c1ca7573ad3a4b534263a57fe58d1c01c42bcd0..30af83f23ccdb37fb5638a1bfa360a5716b25fc8 100644 (file)
--- a/src/test/regress/expected/aggregates.out
+++ b/src/test/regress/expected/aggregates.out
@@ -2033,8 +2033,8 @@ explain (costs off) select * from v_pagg_test order by y;
                                        ->  Parallel Seq Scan on pagg_test
 (13 rows)
 
-set max_parallel_workers_per_gather = 0;
 -- Ensure results are the same without parallel aggregation.
+set max_parallel_workers_per_gather = 0;
 select * from v_pagg_test order by y;
  y | tmin | tmax | tndistinct | bmin | bmax | bndistinct | amin | amax | andistinct | aamin | aamax | aandistinct 
 ---+------+------+------------+------+------+------------+------+------+------------+-------+-------+-------------
@@ -2050,6 +2050,24 @@ select * from v_pagg_test order by y;
  9 |   19 | 4999 |        250 | 1019 | 999  |        250 |   19 | 4999 |        250 |    19 |  4999 |         250
 (10 rows)
 
+-- Check that we don't fail on anonymous record types.
+set max_parallel_workers_per_gather = 2;
+explain (costs off)
+select array_dims(array_agg(s)) from (select * from pagg_test) s;
+                 QUERY PLAN                 
+--------------------------------------------
+ Aggregate
+   ->  Gather
+         Workers Planned: 2
+         ->  Parallel Seq Scan on pagg_test
+(4 rows)
+
+select array_dims(array_agg(s)) from (select * from pagg_test) s;
+ array_dims 
+------------
+ [1:5000]
+(1 row)
+
 -- Clean up
 reset max_parallel_workers_per_gather;
 reset bytea_output;

diff --git a/src/test/regress/sql/aggregates.sql b/src/test/regress/sql/aggregates.sql
index 1a18ca3d8fe207ab48faec2840c97be61906edbf..675b23add5962ac700a908e8c87e54e693302b10 100644 (file)
--- a/src/test/regress/sql/aggregates.sql
+++ b/src/test/regress/sql/aggregates.sql
@@ -805,11 +805,16 @@ select * from v_pagg_test order by y;
 -- Ensure parallel aggregation is actually being used.
 explain (costs off) select * from v_pagg_test order by y;
 
-set max_parallel_workers_per_gather = 0;
-
 -- Ensure results are the same without parallel aggregation.
+set max_parallel_workers_per_gather = 0;
 select * from v_pagg_test order by y;
 
+-- Check that we don't fail on anonymous record types.
+set max_parallel_workers_per_gather = 2;
+explain (costs off)
+select array_dims(array_agg(s)) from (select * from pagg_test) s;
+select array_dims(array_agg(s)) from (select * from pagg_test) s;
+
 -- Clean up
 reset max_parallel_workers_per_gather;
 reset bytea_output;