On Tue, 28 Mar 2023 at 17:54, Maxim Boguk <maxim.boguk@gmail.com> wrote: > During an attempt to create a minimal test case I discovered an effect for which I have no explanation: > (all tests with jit=on): > > Run EXPLAIN on the single partition, so far expected results... > explain select * from interview_review_info_archive_p028; > QUERY PLAN > ----------------------------------------------------------------------------------------------- > Seq Scan on interview_review_info_archive_p028 (cost=0.00..361819.08 rows=34546848 width=40) > JIT: > Functions: 2 > Options: Inlining true, Optimization true, Expressions true, Deforming true
It could be something like a dropped column forcing projection of the SELECT *. You might want to try without SELECT * using some subset of columns instead.
Check if columns have been dropped with:
select attnum,attname from pg_Attribute where attrelid='interview_review_info_archive_p028'::Regclass;
David
Hi David,
You 100% right
negotiation_chat_archive=# explain select topic_id,review_id,move_to_invitation_state_time,no_interview_reply_time,review_suggestion_chat_message_creation_time from interview_review_info_archive_p028; QUERY PLAN ----------------------------------------------------------------------------------------------- Seq Scan on interview_review_info_archive_p028 (cost=0.00..361921.00 rows=34563080 width=40)
Exceptionally curious case when select * not equivalent select list_all_columns from table...
Thank you.
The small update - previous explain was wrong (I forgot enable jit)
but general explanation correct
dropping column from test table forcing jit during explain:
set JIT to on;
alter table tables_to_drop.test drop column move_to_invitation_state_time;
vacuum ANALYZE tables_to_drop.test;
negotiation_chat_archive=# explain select * from tables_to_drop.test; QUERY PLAN --------------------------------------------------------------------------------- Seq Scan on test (cost=0.00..361966.20 rows=34567620 width=32) JIT: Functions: 2 Options: Inlining false, Optimization false, Expressions true, Deforming true (4 rows)
