Re: WAL format

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: WAL format
Date: 2009-12-07 20:28:29
Message-ID: 23971.1260217709@sss.pgh.pa.us
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Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> writes:
> In particular I wonder why we bother with the page headers. A much
> simpler format would be:

> - get rid of page headers, except for the header at the beginning of
> each WAL segment
> - get rid of continuation records
> - at the end of WAL segment, when there's not enough space to write the
> next WAL record, always write an XLOG SWITCH record to fill the rest of
> the segment.

What do you do with a WAL record that doesn't fit in a segment? (They
do exist.) I don't think you can eliminate continuation records.
You could maybe use them only at segment boundaries but I doubt that
makes things any simpler than they are now.

regards, tom lane

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  • WAL format at 2009-12-07 19:28:38 from Heikki Linnakangas

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