Re: Theory question

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?