Re: Slow DROP INDEX

Based on my experience, "drop index" is waiting for a chance to place the
lock. If all those queries are within the same connection, "drop index" has
to wait until that connection disconnected.

John Li

-----Original Message-----
From: pgsql-hackers-owner@postgresql.org
[mailto:pgsql-hackers-owner@postgresql.org]On Behalf Of Rod Taylor
Sent: Monday, February 16, 2004 10:56 AM
To: Tom Lane
Cc: PostgreSQL Development
Subject: Re: [HACKERS] Slow DROP INDEX

On Mon, 2004-02-16 at 13:03, Tom Lane wrote:
> Rod Taylor <pg@rbt.ca> writes:
> > The real question is why does DROP INDEX take more than a couple of
> > seconds to complete? It is not held up by locked.
>
> AFAICS it shouldn't take any time to complete.  I think you're mistaken
> and it is blocking on a lock (it will want exclusive lock on the table).
> Everyone else will then queue up behind it.

I not convinced it is waiting on a lock. The queries on that table are
very short (couple of milliseconds) -- but there are a ton of them. All
backends appear to be idle (pg_stat_activity with command shown) when we
start the drop and shortly after huge backups occur.


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