Re: I/O on select count(*) - Mailing list pgsql-performance

From Greg Smith
Subject Re: I/O on select count(*)
Date
Msg-id Pine.GSO.4.64.0805180113450.8667@westnet.com
Whole thread Raw
In response to Re: I/O on select count(*)  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: I/O on select count(*)  (Decibel! <decibel@decibel.org>)
Re: I/O on select count(*)  (Decibel! <decibel@decibel.org>)
List pgsql-performance
I just collected all the good internals information included in this
thread and popped it onto http://wiki.postgresql.org/wiki/Hint_Bits 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@gregsmith.com http://www.gregsmith.com Baltimore, MD

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