Horton

Re: Configuring synchronous replication

Csaba Nagy <ncslists@googlemail.com>

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From: Csaba Nagy <ncslists@googlemail.com>
To: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Cc: Csaba Nagy <ncslists@googlemail.com>, Robert Haas <robertmhaas@gmail.com>, jd@commandprompt.com, Thom Brown <thom@linux.com>, Bruce Momjian <bruce@momjian.us>, Andrew Dunstan <andrew@dunslane.net>, Dave Page <dpage@pgadmin.org>, Peter Eisentraut <peter_e@gmx.net>, Tom Lane <tgl@sss.pgh.pa.us>, Fujii Masao <masao.fujii@gmail.com>, Josh Berkus <josh@agliodbs.com>, pgsql-hackers@postgresql.org
Date: 2010-09-23T13:59:30Z
Lists: pgsql-hackers 
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.