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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Lists: | pgsql-general |
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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