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* Re: A way to optimize sql about the last temporary-related row
@ 2024-06-28 17:51 Richard Welty <[email protected]>
0 siblings, 1 reply; 2+ messages in thread
From: Richard Welty @ 2024-06-28 17:51 UTC (permalink / raw)
To: agharta82 <[email protected]>; +Cc: David Rowley <[email protected]>; PostgreSQL General <[email protected]>
not really in direct response to this conversation, but is there any reason
on the face of the planet why read receipts need to be sent to every single
recipient of the mailing list?
just saying,
richard
---- On Fri, 28 Jun 2024 03:20:26 -0400 <[email protected]> wrote ---
HOO-HA! This is HUGE!
Only 2.2 seconds on my data!!!! Amazing!
distinct on (field) followed by "*" is a hidden gem!
Thank you so much and thanks to everyone who helped me! Thank
you very much!!
Cheers,
Agharta
Il 27/06/24 6:16 PM, David Rowley ha
scritto:
On Fri, 28 Jun 2024, 3:20
am mailto:[email protected],
<mailto:[email protected]>
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
^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: A way to optimize sql about the last temporary-related row
@ 2024-06-28 19:07 agharta agharta <[email protected]>
parent: Richard Welty <[email protected]>
0 siblings, 0 replies; 2+ messages in thread
From: agharta agharta @ 2024-06-28 19:07 UTC (permalink / raw)
To: Richard Welty <[email protected]>; +Cc: David Rowley <[email protected]>; PostgreSQL General <[email protected]>
Sorry, my wrong settings on pc mail client.
Sorry again.
Agharta
Il ven 28 giu 2024, 19:51 Richard Welty <[email protected]> ha scritto:
> not really in direct response to this conversation, but is there any reason
> on the face of the planet why read receipts need to be sent to every single
> recipient of the mailing list?
>
> just saying,
> richard
>
>
>
> ---- On Fri, 28 Jun 2024 03:20:26 -0400 * <[email protected]
> <[email protected]>>* wrote ---
>
> HOO-HA! This is HUGE!
>
> Only 2.2 seconds on my data!!!! Amazing!
>
> distinct on (field) *followed by "*" *is a hidden gem!
>
> Thank you so much and thanks to everyone who helped me! Thank you very
> much!!
>
> Cheers,
>
> Agharta
>
>
>
>
> Il 27/06/24 6:16 PM, David Rowley ha scritto:
>
>
>
> On Fri, 28 Jun 2024, 3:20 am [email protected], <[email protected]>
> 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
>
>
>
>
>
^ permalink raw reply [nested|flat] 2+ messages in thread
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2024-06-28 17:51 Re: A way to optimize sql about the last temporary-related row Richard Welty <[email protected]>
2024-06-28 19:07 ` agharta agharta <[email protected]>
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