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Re: I/O on select count(*)

From: Greg Smith <gsmith(at)gregsmith(dot)com>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: I/O on select count(*)
Date: 2008-05-18 05:28:26
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
I just collected all the good internals information included in this 
thread and popped it onto where 
I'll continue to hack away at the text until it's readable.  Thanks to 
everyone who answered my questions here, that's good progress toward 
clearing up a very underdocumented area.

I note a couple of potential TODO items not on the official list yet that 
came up during this discussion:

-Smooth latency spikes when switching commit log pages by preallocating 
cleared pages before they are needed

-Improve bulk loading by setting "frozen" hint bits for tuple inserts 
which occur within the same database transaction as the creation of the 
table into which they're being inserted

Did I miss anything?  I think everything brought up falls either into one 
of those two or the existing "Consider having the background writer update 
the transaction status hint bits..." TODO.

* Greg Smith gsmith(at)gregsmith(dot)com Baltimore, MD

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