Re: Problems with Large Databases - Mailing list pgsql-general

From Peter Eisentraut
Subject Re: Problems with Large Databases
Date
Msg-id Pine.LNX.4.21.0006040332020.348-100000@localhost.localdomain
Whole thread Raw
In response to Problems with Large Databases  ("carl garland" <carlhgarland@hotmail.com>)
List pgsql-general
carl garland writes:

> This didnt really answer the initial question of how long does it take
> to locate a table in a large 1000000+ table db and where and when do
> these lookups occur.

In the current system there are several places that do sequential scans on
pg_class (which holds information on tables and indexes). Most if these
look quite unnecessary and are on the hit-list, but using stock sources
you will definitely have performance problems.

Assuming that all of these are converted to index scans eventually, you
can test the performance yourself by creating a 1000000+ row table,
defining an index and querying it a bunch of times. At that point I
believe the file system will be at least as much of a problem.

--
Peter Eisentraut                  Sernanders väg 10:115
peter_e@gmx.net                   75262 Uppsala
http://yi.org/peter-e/            Sweden



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