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* Re: A way to optimize sql about the last temporary-related row
@ 2024-06-27 15:27 Ron Johnson <[email protected]>
2024-06-27 15:33 ` Re: A way to optimize sql about the last temporary-related row [email protected] <[email protected]>
0 siblings, 1 reply; 3+ messages in thread
From: Ron Johnson @ 2024-06-27 15:27 UTC (permalink / raw)
To: pgsql-generallists.postgresql.org <[email protected]>
On Thu, Jun 27, 2024 at 11:20 AM [email protected] <[email protected]>
wrote:
[snip]
> -- insert 4M records
> insert into test_table(pk_id) select generate_series(1,4000000,1);
>
> -- now set some random data, distribuited between specific ranges (as in
> my production table)
> update test_table set
> datetime_field_1 = timestamp '2000-01-01 00:00:00' + random() *
> (timestamp '2024-05-31 23:59:59' - timestamp '2000-01-01 00:00:00'),
> integer_field_1 = floor(random() * (6-1+1) + 1)::int,
> integer_field_2 = floor(random() * (200000-1+1) + 1)::int;
>
>
> -- indexes
> CREATE INDEX idx_test_table_integer_field_1 ON test_table(integer_field_1);
> CREATE INDEX xtest_table_datetime_field_1 ON test_table(datetime_field_1
> desc);
> CREATE INDEX idx_test_table_integer_field_2 ON test_table(integer_field_2);
>
>
Off-topic: save some resources by vacuuming before creating indices.
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: A way to optimize sql about the last temporary-related row
2024-06-27 15:27 Re: A way to optimize sql about the last temporary-related row Ron Johnson <[email protected]>
@ 2024-06-27 15:33 ` [email protected] <[email protected]>
2024-06-27 15:43 ` Re: A way to optimize sql about the last temporary-related row Ron Johnson <[email protected]>
0 siblings, 1 reply; 3+ messages in thread
From: [email protected] @ 2024-06-27 15:33 UTC (permalink / raw)
To: [email protected]
Hi,
You are right. Too quickly copy-paste on my part :-)
I take this opportunity to add a NOT insignificant detail.
Before executing the select query I clear the cache:
systemctl stop postgresql-16 && sync && echo 3 >
/proc/sys/vm/drop_caches && systemctl start postgresql-16
I need to get a performance result even if data is not in cache.
My best regards,
Agharta
Il 27/06/24 5:27 PM, Ron Johnson ha scritto:
> On Thu, Jun 27, 2024 at 11:20 AM [email protected]
> <[email protected]> wrote:
> [snip]
>
> -- insert 4M records
> insert into test_table(pk_id) select generate_series(1,4000000,1);
>
> -- now set some random data, distribuited between specific ranges
> (as in
> my production table)
> update test_table set
> datetime_field_1 = timestamp '2000-01-01 00:00:00' + random() *
> (timestamp '2024-05-31 23:59:59' - timestamp '2000-01-01 00:00:00'),
> integer_field_1 = floor(random() * (6-1+1) + 1)::int,
> integer_field_2 = floor(random() * (200000-1+1) + 1)::int;
>
>
> -- indexes
> CREATE INDEX idx_test_table_integer_field_1 ON
> test_table(integer_field_1);
> CREATE INDEX xtest_table_datetime_field_1 ON
> test_table(datetime_field_1
> desc);
> CREATE INDEX idx_test_table_integer_field_2 ON
> test_table(integer_field_2);
>
>
> Off-topic: save some resources by vacuuming before creating indices.
>
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: A way to optimize sql about the last temporary-related row
2024-06-27 15:27 Re: A way to optimize sql about the last temporary-related row Ron Johnson <[email protected]>
2024-06-27 15:33 ` Re: A way to optimize sql about the last temporary-related row [email protected] <[email protected]>
@ 2024-06-27 15:43 ` Ron Johnson <[email protected]>
0 siblings, 0 replies; 3+ messages in thread
From: Ron Johnson @ 2024-06-27 15:43 UTC (permalink / raw)
To: pgsql-general
On Thu, Jun 27, 2024 at 11:33 AM [email protected] <[email protected]>
wrote:
> Hi,
>
> You are right. Too quickly copy-paste on my part :-)
>
> I take this opportunity to add a NOT insignificant detail.
>
> Before executing the select query I clear the cache:
>
> systemctl stop postgresql-16 && sync && echo 3 > /proc/sys/vm/drop_caches
> && systemctl start postgresql-16
>
> I need to get a performance result even if data is not in cache.
>
In addition to David's suggestion, consider the pg_prewarm extension:
https://www.postgresql.org/docs/current/pgprewarm.html
^ permalink raw reply [nested|flat] 3+ messages in thread
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