Horton

Re: 2PC-induced lockup

Peter Eisentraut <peter_e@gmx.net>

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From: Peter Eisentraut <peter_e@gmx.net>
To: Heikki Linnakangas <heikki@enterprisedb.com>
Cc: pgsql-hackers@postgresql.org, Chris Browne <cbbrowne@acm.org>
Date: 2007-07-11T20:08:12Z
Lists: pgsql-hackers 
Heikki Linnakangas wrote:

> Why does the application LOCK pg_auth?

It does it with NOWAIT to determine if some other connection had already 
locked it (because it was modifying some roles) in order not to lock up 
the program.  This (or something like it, because this doesn't work, 
after all) is unfortunately necessary because schema changes don't obey 
ordinary snapshot rules.

-- 
Peter Eisentraut
http://developer.postgresql.org/~petere/