Re: Deadlock bug

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>
To: Nicolas Barbier <nicolas.barbier@gmail.com>
Cc: Simon Riggs <simon@2ndquadrant.com>, Markus Wanner <markus@bluegap.ch>, pgsql-hackers@postgresql.org
Date: 2010-08-25T14:57:28Z
Lists: pgsql-hackers
Nicolas Barbier <nicolas.barbier@gmail.com> writes:
> 2010/8/25 Simon Riggs <simon@2ndquadrant.com>:
>> You're exactly correct and I now understand Markus' comment. Do you
>> think that exact meaning prevents my proposal from being useful?

> Not at all, because I guess that updates to non-UNIQUE columns are way
> more common that updates to UNIQUE columns.

In particular, HOT updates are known useful even though they have
that restriction and more.

It strikes me that a possibly useful simplification of the idea is a
lock type that allows HOT updates and not non-HOT ones; or more
precisely not ones that change any indexed columns --- if the row ends
up having to go off-page for lack of space, that need not concern us.

			regards, tom lane