Re: Configuring synchronous replication

From: Csaba Nagy <ncslists(at)googlemail(dot)com>
To: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
Cc: Csaba Nagy <ncslists(at)googlemail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, jd(at)commandprompt(dot)com, Thom Brown <thom(at)linux(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>, Andrew Dunstan <andrew(at)dunslane(dot)net>, Dave Page <dpage(at)pgadmin(dot)org>, Peter Eisentraut <peter_e(at)gmx(dot)net>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Fujii Masao <masao(dot)fujii(at)gmail(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Configuring synchronous replication
Date: 2010-09-23 13:59:30
Message-ID: 1285250370.2969.66.camel@pcd12478
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On Thu, 2010-09-23 at 16:18 +0300, Heikki Linnakangas wrote:
> There's a program called pg_readahead somewhere on pgfoundry by NTT that
> will help if it's the single-threadedness of I/O. Before handing the WAL
> file to the server, it scans it through and calls posix_fadvise for all
> the blocks that it touches. When the server then replays it, the data
> blocks are already being fetched by the OS, using the whole RAID array.

That sounds useful, thanks for the hint !

But couldn't this also be directly built in to WAL recovery process ? It
would probably help a lot for recovering from a crash too. We did have
recently a crash and it took hours to recover.

I will try it out as soon as I get the time to set it up...

[searching pgfoundry]

Unfortunately I can't find it, and google is also not very helpful. Do
you happen to have some links to it ?

Cheers,
Csaba.

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