Re: ALTER TABLE lock strength reduction patch is unsafe

On Fri, Jun 17, 2011 at 3:08 PM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> Not so. The extra locking would only occur on the first lock
> acquisition after DDL operations occur. If that was common then your
> other performance patch would not be an effective optimisation. There
> is no additional locking from what I've proposed in the common code
> path - that's why we have a relcache.

The extra locking would also occur when *initially* building relcache
entries. In other words, this would increase - likely quite
significantly - the overhead of backend startup. It's not going to be
sufficient to do this just for pg_class; I think you'll have to do it
for pg_attribute, pg_attrdef, pg_constraint, pg_index, pg_trigger,
pg_rewrite, and maybe a few others I'm not thinking of right now.

--
Robert Haas
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