Re: Let's invent a function to report lock-wait-blocking PIDs

Greg Smith wrote:

> Note that an EXPLAIN based approach doesn't solve all the problems
> in this area, because the trickiest ones I run into are ALTER TABLE
> changes--which you can't EXPLAIN. Some API that dumps the locks an
> arbitrary statement acquired just before it exits would be ideal.
> When a user can ask "what locks did an ALTER TABLE adding a foreign
> key take and what order were they grabbed in?", that would solve the
> hardest of the questions I see in the field.

Hm, this sounds like something we could apply to event triggers -- at
ddl_command_end, you would run a SRF, say
pg_event_trigger_acquired_locks() to get what you want.

--
Álvaro Herrera http://www.2ndQuadrant.com/
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