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Re: UPDATEDs slowing SELECTs in a fully cached database

From: lars <lhofhansl(at)yahoo(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, Ivan Voras <ivoras(at)freebsd(dot)org>, pgsql-performance(at)postgresql(dot)org
Subject: Re: UPDATEDs slowing SELECTs in a fully cached database
Date: 2011-07-17 02:12:47
Message-ID: 4E22451F.9070803@yahoo.com (view raw or flat)
Thread:
Lists: pgsql-performance
On 07/14/2011 08:47 AM, Tom Lane wrote:
>
> The implementation I was imagining was to define another bit in the info
> parameter for XLogInsert, say XLOG_NON_TRANSACTIONAL.  This could be a
> high-order bit that would not go to disk.  Anytime it was *not* set,
> XLogInsert would set a global boolean that would remember that the
> current transaction wrote a transactional WAL record.  This is the
> right default since the vast majority of call sites are writing records
> that we would want to have flushed at commit.  There are just a couple
> of places that would need to be changed to add this flag to their calls.
>
> 			regards, tom lane
>

If you have a patch in mind I'm happy to test it on my setup and report 
back.

-- Lars


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