Re: Compressing WAL

From: Qingqing Zhou
Subject: Re: Compressing WAL
Date: ,
Msg-id: d355d3$2ht4$1@news.hub.org
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In response to: Compressing WAL  ("Jim C. Nasby")
List: pgsql-performance

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Compressing WAL  ("Jim C. Nasby", )
 Re: Compressing WAL  (Bruce Momjian, )
  Re: Compressing WAL  ("Jim C. Nasby", )
  Re: Compressing WAL  (Simon Riggs, )
   Re: Compressing WAL  (Bruce Momjian, )
 Re: Compressing WAL  ("Qingqing Zhou", )

""Jim C. Nasby"" <> writes
> Has anyone looked at compressing WAL's before writing to disk? On a
> system generating a lot of WAL it seems there might be some gains to be
> had WAL data could be compressed before going to disk, since today's
> machines are generally more I/O bound than CPU bound. And unlike the
> base tables, you generally don't need to read the WAL, so you don't
> really need to worry about not being able to quickly scan through the
> data without decompressing it.
> --

The problem is where you put the compression code? If you put it inside
XLogInsert lock or XLogWrite lock, which will hold the lock too long? Or
anywhere else?

Regards,
Qingqing





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