From: Sergey Burladyan <eshkinkot@gmail.com>
To: pgsql-performance@postgresql.org
Subject: Why creating GIN table index is so slow than inserting data into empty table with the same index?
Date: Tue, 24 Mar 2009 03:59:34 +0300
Message-ID: <874oxjrb0p.fsf@seb.progtech.ru> (raw)
example:
select version();
version
--------------------------------------------------------------------------------------------
PostgreSQL 8.3.6 on i486-pc-linux-gnu, compiled by GCC gcc-4.3.real (Debian 4.3.3-3) 4.3.3
show maintenance_work_mem ;
maintenance_work_mem
----------------------
128MB
create table a (i1 int, i2 int, i3 int, i4 int, i5 int, i6 int);
insert into a select n, n, n, n, n, n from generate_series(1, 100000) as n;
INSERT 0 100000
Время: 570,110 мс
create index arr_gin on a using gin ( (array[i1, i2, i3, i4, i5, i6]) );
CREATE INDEX
Время: 203068,314 мс
truncate a;
drop index arr_gin ;
create index arr_gin on a using gin ( (array[i1, i2, i3, i4, i5, i6]) );
CREATE INDEX
Время: 3,246 мс
insert into a select n, n, n, n, n, n from generate_series(1, 100000) as n;
INSERT 0 100000
Время: 2405,481 мс
select pg_size_pretty(pg_total_relation_size('a')) as total,
pg_size_pretty(pg_relation_size('a')) as table;
total | table
---------+---------
9792 kB | 5096 kB
203068.314 ms VS 2405.481 ms, is this behaviour normal ?
Thanks !
--
Sergey Burladyan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: eshkinkot@gmail.com
Subject: Re: Why creating GIN table index is so slow than inserting data into empty table with the same index?
In-Reply-To: <874oxjrb0p.fsf@seb.progtech.ru>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox