EXPLAIN ANALYZE for parallel query doesn't report the SortMethod information.

Hi,

I found $SUBJECT while trying to test parallel queries. Is this a bug?


In not parallel mode, EXPLAIN ANALYZE reports the information about
Sort Method as follows.

=# EXPLAIN ANALYZE SELECT * FROM pgbench_accounts ORDER BY bid;
 QUERY PLAN
 

-----------------------------------------------------------------------------------------------------------------------------------Sort
(cost=180739.34..183239.34 rows=1000000 width=97) (actual
 
time=1501.342..1836.057 rows=1000000 loops=1)  Sort Key: bid  Sort Method: external sort  Disk: 104600kB  ->  Seq Scan
onpgbench_accounts  (cost=0.00..26394.00 rows=1000000
 
width=97) (actual time=0.013..179.315 rows=1000000 loops=1)


However, in parallel mode, it's not reported, as follows.

=# SET force_parallel_mode TO on;
=# EXPLAIN ANALYZE SELECT * FROM pgbench_accounts ORDER BY bid;
    QUERY
 
PLAN

-----------------------------------------------------------------------------------------------------------------------------------------Gather
(cost=181739.34..284239.34 rows=1000000 width=97) (actual
 
time=1507.138..2394.028 rows=1000000 loops=1)  Workers Planned: 1  Workers Launched: 1  Single Copy: true  ->  Sort
(cost=180739.34..183239.34rows=1000000 width=97) (actual
 
time=1503.112..1901.117 rows=1000000 loops=1)        Sort Key: bid        ->  Seq Scan on pgbench_accounts
(cost=0.00..26394.00
rows=1000000 width=97) (actual time=0.021..181.079 rows=1000000
loops=1)

Regards,

-- 
Fujii Masao