Re: Documentation Update: WAL & Checkpoints - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: Documentation Update: WAL & Checkpoints
Date
Msg-id 200904101516.n3AFGIk27679@momjian.us
Whole thread Raw
In response to Re: Documentation Update: WAL & Checkpoints  (Michael Renner <michael.renner@amd.co.at>)
List pgsql-hackers
Michael Renner wrote:
> Bruce Momjian wrote:
> > Michael Renner wrote:
> >> Hi,
> >>
> >> this is a small update to the first paragraph of the WAL configuration 
> >> chapter, going into more detail WRT redo vs. checkpoint records, since 
> >> the underlying behavior is currently only deducible from the source. I'm 
> >> not perfectly sure if I got everything right, so feel free to change as 
> >> necessary.
> 
> [..]
> 
> > I read over you patch and I was afraid it was trying to put too much
> > information into a single paragraph, so I added a second paragraph that
> > just talks about checkpoint smoothing.  I did not address the issue of
> > when the REDO WAL entry is written --- that is probably too much detail
> > for our documentation.
> 
> Too bad, understanding how this works is necessary to properly implement 
> more complex log shipping setups. Maybe /backend/access/transam/README 
> instead? Or specific "under the hood" paragraphs for selected areas of 
> the DBMS?

Let's back up and let me ask why it is important for a user to know when
the REDO record is written vs. when the checkpoint completes, and how
that affects more complex log shipping setups.

This detail is certainly appropriate for /backend/access/transam/README
so if you could send in a patch, that would be great.

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com
 + If your life is a hard drive, Christ can be your backup. +


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