On Fri, 28 Jun 2024, 3:20 am aghart...@gmail.com, <aghart...@gmail.com> wrote:
> > Now the query: > explain (verbose, buffers, analyze) > with last_table_ids as materialized( > select xx from ( > select LAST_VALUE(pk_id) over (partition by integer_field_2 order by > datetime_field_1 RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED > FOLLOWING) xx > from test_table > where integer_field_1 = 1 > and datetime_field_1 <= CURRENT_TIMESTAMP > ) ww group by ww.xx > > ), > last_row_per_ids as ( > select tt.* from last_table_ids lt > inner join test_table tt on (tt.pk_id = lt.xx) > > ) > > select * /* or count(*) */ from last_row_per_ids; > > > This query, on my PC, takes 46 seconds!!! > (Away from laptop and using my phone) Something like: select distinct on (integer_field_2) * from test_table where integer_field_1 = 1 and datetime_field_1 <= CURRENT_TIMESTAMP order by integer_field_2,datetime_field_1 desc; Might run a bit faster. However if it's slow due to I/O then maybe not much faster. Your version took about 5 seconds on my phone and my version ran in 1.5 seconds. It's difficult for me to check the results match with each query from my phone. A quick scan of the first 10 or so records looked good. If the updated query is still too slow on cold cache then faster disks might be needed. David >
