Skip site navigation (1) Skip section navigation (2)

pgsql: Fix a performance problem in databases with large numbers of

From: tgl(at)postgresql(dot)org (Tom Lane)
To: pgsql-committers(at)postgresql(dot)org
Subject: pgsql: Fix a performance problem in databases with large numbers of
Date: 2007-01-11 23:06:16
Message-ID: 20070111230616.EB73B9FB1C2@postgresql.org (view raw or flat)
Thread:
Lists: pgsql-committers
Log Message:
-----------
Fix a performance problem in databases with large numbers of tables
(or other types of pg_class entry): the function pgstat_vacuum_tabstat,
invoked during VACUUM startup, had runtime proportional to the number of
stats table entries times the number of pg_class rows; in other words
O(N^2) if the stats collector's information is reasonably complete.
Replace list searching with a hash table to bring it back to O(N)
behavior.  Per report from kim at myemma.com.

Back-patch as far as 8.1; 8.0 and before use different coding here.

Tags:
----
REL8_1_STABLE

Modified Files:
--------------
    pgsql/src/backend/postmaster:
        pgstat.c (r1.111.2.6 -> r1.111.2.7)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/postmaster/pgstat.c.diff?r1=1.111.2.6&r2=1.111.2.7)

pgsql-committers by date

Next:From: Michael MeskesDate: 2007-01-12 10:00:14
Subject: pgsql: Simplified regression handling Added patch by Joachim to work
Previous:From: Tom LaneDate: 2007-01-11 23:06:09
Subject: pgsql: Fix a performance problem in databases with large numbers of

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group