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Re: Much Ado About COUNT(*)

From: Jeff Davis <jdavis-pgsql(at)empires(dot)org>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Much Ado About COUNT(*)
Date: 2005-01-18 23:01:01
Message-ID: 1106089261.2886.575.camel@jeff (view raw or flat)
Thread:
Lists: pgsql-announcepgsql-hackerspgsql-patches
> Certainly not; ACID was a recognized goal long before anyone thought of
> MVCC.  You do need much more locking to make it work without MVCC,
> though --- for instance, a reader that is interested in a just-modified
> row has to block until the writer completes or rolls back.
> 
> People who hang around Postgres too long tend to think that MVCC is the
> obviously correct way to do things, but much of the rest of the world
> thinks differently ;-)

Well, that would explain why everyone is so happy with PostgreSQL's
concurrent access performance.

Thanks for the information, although I'm not sure I wanted to be
reminded about complicated locking issues ( I suppose I must have known
that at one time, but perhaps I surpressed it ;-)

Regards,
	Jeff Davis


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