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* postgresql13-llvm jit-13.5-1PGDG.rhel8.x86_64
@ 2021-11-15 04:21 Mladen Gogala <gogala.mladen@gmail.com>
0 siblings, 1 reply; 4+ messages in thread
From: Mladen Gogala @ 2021-11-15 04:21 UTC (permalink / raw)
To: pgsql-performance@lists.postgresql.org
I was trying to upgrade my test 13.4 instance on Oracle Linux 8.4
(x86_64) to 13.5. I can't upgrade postgresql13-llvm jit because Oracle's
and Red Hat repositories still don't have the required version of llvm
(12.1.0.2):
root@postgres mgogala]# rpm -qa|grep llvm
llvm-libs-11.0.1-2.0.1.module+el8.4.0+20397+f876858a.x86_64
llvm7.0-libs-7.0.1-7.el8.x86_64
llvm-test-11.0.1-2.0.1.module+el8.4.0+20397+f876858a.x86_64
llvm-11.0.1-2.0.1.module+el8.4.0+20397+f876858a.x86_64
llvm-static-11.0.1-2.0.1.module+el8.4.0+20397+f876858a.x86_64
llvm-devel-11.0.1-2.0.1.module+el8.4.0+20397+f876858a.x86_64
[root@postgres mgogala]#
I am getting the following error:
postgresql13-llvm jit-13.5-1PGDG.rhel8.x86_64 requires
libLLVM-12.so()(64bit), but none of the providers can be installed.
There is a CentOS8-stream version which solves the problem but I cannot
use that in the office. I will probably have to wait for another month
before OL8 has everything that I need in its repositories. Now, the
question is what kind of an impact will running without llvm-jit have?
According to the links below, llvm-jit effects are quite spectacular:
https://llvm.org/devmtg/2016-09/slides/Melnik-PostgreSQLLLVM.pdf
https://www.pgcon.org/2017/schedule/events/1092.en.html
Now, the question is whether anyone on this list can quantify the
difference? What would be a better option? To wait for the repos to
receive the necessary packages or to run without llvm-jit? In the office
I have some rather large databases and CREATE INDEX CONCURRENTLY and
REINDEX CONCURRENTLY fixes in 13.5 are highly desired but not at the
cost of the overall application performance.
Regards
--
Mladen Gogala
Database Consultant
Tel: (347) 321-1217
https://dbwhisperer.wordpress.com
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: postgresql13-llvm jit-13.5-1PGDG.rhel8.x86_64
@ 2021-11-15 05:04 Pavel Stehule <pavel.stehule@gmail.com>
parent: Mladen Gogala <gogala.mladen@gmail.com>
0 siblings, 1 reply; 4+ messages in thread
From: Pavel Stehule @ 2021-11-15 05:04 UTC (permalink / raw)
To: Mladen Gogala <gogala.mladen@gmail.com>; +Cc: Pgsql Performance <pgsql-performance@lists.postgresql.org>
Hi
> There is a CentOS8-stream version which solves the problem but I cannot
> use that in the office. I will probably have to wait for another month
> before OL8 has everything that I need in its repositories. Now, the
> question is what kind of an impact will running without llvm-jit have?
> According to the links below, llvm-jit effects are quite spectacular:
>
> https://llvm.org/devmtg/2016-09/slides/Melnik-PostgreSQLLLVM.pdf
>
> https://www.pgcon.org/2017/schedule/events/1092.en.html
When JIT was used on very large query with a lot of CASE expr, then JIT has
a positive effect about 50%. On usual large queries, the effect of JIT was
about 20%. Unfortunately, JIT is sensitive to estimation, and the JIT
sometimes increases seconds to queries, although without JIT this query is
executed in ms. When you use a query that can be well calculated in
parallel, then positive effect of JIT is less.
Regards
Pavel
>
>
>
> --
> Mladen Gogala
> Database Consultant
> Tel: (347) 321-1217
> https://dbwhisperer.wordpress.com
>
>
>
>
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: postgresql13-llvm jit-13.5-1PGDG.rhel8.x86_64
@ 2021-11-15 13:56 Mladen Gogala <gogala.mladen@gmail.com>
parent: Pavel Stehule <pavel.stehule@gmail.com>
0 siblings, 1 reply; 4+ messages in thread
From: Mladen Gogala @ 2021-11-15 13:56 UTC (permalink / raw)
To: Pavel Stehule <pavel.stehule@gmail.com>; +Cc: Pgsql Performance <pgsql-performance@lists.postgresql.org>
On 11/15/21 00:04, Pavel Stehule wrote:
>
> Hi
>
>
> There is a CentOS8-stream version which solves the problem but I
> cannot
> use that in the office. I will probably have to wait for another
> month
> before OL8 has everything that I need in its repositories. Now, the
> question is what kind of an impact will running without llvm-jit
> have?
> According to the links below, llvm-jit effects are quite spectacular:
>
> https://llvm.org/devmtg/2016-09/slides/Melnik-PostgreSQLLLVM.pdf
>
> https://www.pgcon.org/2017/schedule/events/1092.en.html
>
>
> When JIT was used on very large query with a lot of CASE expr, then
> JIT has a positive effect about 50%. On usual large queries, the
> effect of JIT was about 20%. Unfortunately, JIT is sensitive to
> estimation, and the JIT sometimes increases seconds to queries,
> although without JIT this query is executed in ms. When you use a
> query that can be well calculated in parallel, then positive effect of
> JIT is less.
>
> Regards
>
> Pavel
Thanks Pavel, you answered my question. I'll wait with the upgrade.
Regards
--
Mladen Gogala
Database Consultant
Tel: (347) 321-1217
https://dbwhisperer.wordpress.com
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: postgresql13-llvm jit-13.5-1PGDG.rhel8.x86_64
@ 2021-11-15 14:17 Rick Otten <rottenwindfish@gmail.com>
parent: Mladen Gogala <gogala.mladen@gmail.com>
0 siblings, 0 replies; 4+ messages in thread
From: Rick Otten @ 2021-11-15 14:17 UTC (permalink / raw)
To: Pgsql Performance <pgsql-performance@lists.postgresql.org>; +Cc: Pavel Stehule <pavel.stehule@gmail.com>; Mladen Gogala <gogala.mladen@gmail.com>
On Mon, Nov 15, 2021 at 8:57 AM Mladen Gogala <gogala.mladen@gmail.com>
wrote:
>
> On 11/15/21 00:04, Pavel Stehule wrote:
>
>
> Hi
>
>
>> There is a CentOS8-stream version which solves the problem but I cannot
>> use that in the office. I will probably have to wait for another month
>> before OL8 has everything that I need in its repositories. Now, the
>> question is what kind of an impact will running without llvm-jit have?
>> According to the links below, llvm-jit effects are quite spectacular:
>>
>> https://llvm.org/devmtg/2016-09/slides/Melnik-PostgreSQLLLVM.pdf
>>
>> https://www.pgcon.org/2017/schedule/events/1092.en.html
>
>
> When JIT was used on very large query with a lot of CASE expr, then JIT
> has a positive effect about 50%. On usual large queries, the effect of JIT
> was about 20%. Unfortunately, JIT is sensitive to estimation, and the JIT
> sometimes increases seconds to queries, although without JIT this query is
> executed in ms. When you use a query that can be well calculated in
> parallel, then positive effect of JIT is less.
>
> Regards
>
> Pavel
>
>
> Thanks Pavel, you answered my question. I'll wait with the upgrade.
>
>
>
FWIW, there was a lively discussion on the postgresql subreddit over the
weekend on JIT:
https://www.reddit.com/r/PostgreSQL/comments/qtsif5/cascade_of_doom_jit_and_how_a_postgres_update_le...
(lively for that subreddit anyway)
^ permalink raw reply [nested|flat] 4+ messages in thread
end of thread, other threads:[~2021-11-15 14:17 UTC | newest]
Thread overview: 4+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2021-11-15 04:21 postgresql13-llvm jit-13.5-1PGDG.rhel8.x86_64 Mladen Gogala <gogala.mladen@gmail.com>
2021-11-15 05:04 ` Pavel Stehule <pavel.stehule@gmail.com>
2021-11-15 13:56 ` Mladen Gogala <gogala.mladen@gmail.com>
2021-11-15 14:17 ` Rick Otten <rottenwindfish@gmail.com>
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