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Revision as of 00:19, 25 May 2006

General

Setup

Storage

As for every tranactional database, disk I/O is the main limiting factor for PostgresSQL. If you plan to deploy a high-usage database please take some precautions on the used storage. Use either a RAID 1 or 10 and choose a FS that does fast block-IO (ext2).

Accounts and permissions

When starting with a fresh database, you've to create some users first before you can start using it.

Basic steps:

su - postgresql
createuser -P <user>
createdb -O <user> <db>

Also be sure to tune the pg_hba.conf in the data-directory to your needs. To emulate MySQLs default "every user needs to authenticate from everywhere"-semantics use the following config:

local   all         all                               md5
host    all         all         127.0.0.1/32          md5
host    all         all         ::1/128               md5 

Maintenance

Vacuuming

What?

Since PostgresSQL is a transactional database, old rows don't get actually removed/replaced when you update/delete them (since they might be still needed in older/long running transactions). To actually free them you need to issue a vacuum.

A normal vacuum will only mark deprecated rows for reuse, to actually reclaim diskspace (e.g. when having deleted large amounts of data) you need to issue a full vacuum. Please note that it might be faster to backup the data you want to keep and truncate the table if you plan to remove large portions of a table.

autovacuum

Fixing broken databases

set zero_damaged_pages to on; vacuum; pray;