Re: Theory question

From: Jayadevan <maymala(dot)jayadevan(at)gmail(dot)com>
To: pgsql-general(at)postgresql(dot)org
Subject: Re: Theory question
Date: 2013-11-14 02:28:15
Message-ID: 1384396095509-5778272.post@n5.nabble.com
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Jeff Janes wrote
> No. The checkpointer writes all data that was dirty as of a certain time
> (the start of the checkpoint) regardless of how often it was used since
> dirtied, and the background writer writes data that hasn't been used
> recently, regardless of when it was first dirtied. Neither knows or cares
> whether the data being written was committed, rolled back, or still in
> progress.

Thank you. So checkpointer writes "all dirty data" while backgrounder writes
"all or some dirty data" depending on some (Clocksweep?) algorithm. Correct?
From this discussion
http://postgresql.1045698.n5.nabble.com/Separating-bgwriter-and-checkpointer-td4808791.html
<http://postgresql.1045698.n5.nabble.com/Separating-bgwriter-and-checkpointer-td4808791.html>
the bgwrites has some 'other dutties'. Probably those involve marking the
buffers - when they were last used, how frequently etc?

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