Wiki / Configuration Parameters

The number of dirty buffers written in each round is based on the number of new buffers that have been needed by server processes during recent rounds. The average recent need is multiplied by bgwriter_lru_multiplier to arrive at an estimate of the number of buffers that will be needed during the next round. Dirty buffers are written until there are that many clean, reusable buffers available. (However, no more than bgwriter_lru_maxpages buffers will be written per round.) Thus, a setting of 1.0 represents a “just in time” policy of writing exactly the number of buffers predicted to be needed. Larger values provide some cushion against spikes in demand, while smaller values intentionally leave writes to be done by server processes. The default is 2.0. This parameter can only be set in the postgresql.conf file or on the server command line.

English manual coverage begins with PostgreSQL 7.4. Source history and runtime observations have their own recorded version boundaries.

boot val

2

category

Resource Usage / Background Writer

context

sighup

documented

true

enumvals

Unknown

extra desc

Unknown

lang

en

max val

10

metadata version

18

min val

0

name

bgwriter_lru_multiplier

short desc

Multiple of the average buffer usage to free per round.

source

pg-settings-source-snapshot

unit

Unknown

vartype

real