RE: Another little xlog change idea - Mailing list pgsql-hackers

From Mikheev, Vadim
Subject RE: Another little xlog change idea
Date
Msg-id 8F4C99C66D04D4118F580090272A7A234D331A@sectorbase1.sectorbase.com
Whole thread Raw
In response to Another little xlog change idea  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
> As long as I'm about to change the xlog page headers, I have another
> little idea.  Wouldn't it be a good idea to allow three backup pages
> per xlog record, not only two?  It seems like three pages would be
> a natural requirement for logging operations like index page splits.

On index splits we don't backup left and right whole pages - just part
of pages filled by index tuples. This saves us ~ 8K for indices with
small keys.

> We could support as many as four pages per record, but that would mean
> having no free global bits in the info byte, which might be a 
> bad idea. I think three page bits and one free bit is a good compromise.
> Thoughts?

You almost forget that we are in beta and should fix bugs, not implement
features which useless in current version -:) Add comments and that will
be enough, no?

Vadim


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