From: | Jesper Pedersen <jesper(dot)pedersen(at)redhat(dot)com> |
---|---|
To: | "Imai, Yoshikazu" <imai(dot)yoshikazu(at)jp(dot)fujitsu(dot)com>, 'Amit Langote' <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, 'Amit Langote' <amitlangote09(at)gmail(dot)com> |
Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Justin Pryzby <pryzby(at)telsasoft(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: speeding up planning with partitions |
Date: | 2019-03-20 14:25:05 |
Message-ID: | 53a80692-c68d-5e11-1014-6441b6e8ca5a@redhat.com |
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Lists: | pgsql-hackers |
Hi,
On 3/19/19 11:15 PM, Imai, Yoshikazu wrote:
> Here the details.
>
> [creating partitioned tables (with 1024 partitions)]
> drop table if exists rt;
> create table rt (a int, b int, c int) partition by range (a);
> \o /dev/null
> select 'create table rt' || x::text || ' partition of rt for values from (' ||
> (x)::text || ') to (' || (x+1)::text || ');' from generate_series(1, 1024) x;
> \gexec
> \o
>
> [select1024.sql]
> \set a random (1, 1024)
> select * from rt where a = :a;
>
> [pgbench]
> pgbench -n -f select1024.sql -T 60
>
>
My tests - using hash partitions - shows that the extra time is spent in
make_partition_pruneinfo() for the relid_subplan_map variable.
64 partitions: make_partition_pruneinfo() 2.52%
8192 partitions: make_partition_pruneinfo() 5.43%
TPS goes down ~8% between the two. The test setup is similar to the above.
Given that Tom is planning to change the List implementation [1] in 13 I
think using the palloc0 structure is ok for 12 before trying other
implementation options.
perf sent off-list.
[1] https://www.postgresql.org/message-id/24783.1551568303%40sss.pgh.pa.us
Best regards,
Jesper
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