Re: including backend ID in relpath of temp rels - updated patch

Excerpts from Robert Haas's message of jue ago 12 13:29:57 -0400 2010:

> We have two existing mechanisms for removing the catalog entries: when
> a backend is first asked to access a temporary file, it does a DROP
> SCHEMA ... CASCADE on any pre-existing temp schema. And a table is in
> wraparound trouble and the owning backend is no longer running,
> autovacuum will drop it. Improving on this seems difficult: if you
> wanted to *guarantee* that the catalog entries were removed before we
> started letting in connections, you'd need to fork a backend per
> database and have each one iterate through all the temp schemas and
> drop them. Considering that the existing code seems to have been
> pretty careful about how this stuff gets handled, I don't think it's
> worth making the whole startup sequence slower for it. What might be
> worth considering is changing the autovacuum policy to eliminate the
> wraparound check, and just have it drop temp table catalog entries for
> any backend not currently running, period.

What about having autovacuum silenty drop the catalog entry if it's a
temp entry for which the underlying file does not exist?

--
Álvaro Herrera <alvherre(at)commandprompt(dot)com>
The PostgreSQL Company - Command Prompt, Inc.
PostgreSQL Replication, Consulting, Custom Development, 24x7 support