Re: Much Ado About COUNT(*)
Jeff Davis <jdavis-pgsql@empires.org>
From: Jeff Davis <jdavis-pgsql@empires.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-hackers@postgresql.org
Date: 2005-01-18T23:01:01Z
Lists: pgsql-hackers
> 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