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 on pgbench_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..183239.34 rows=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