Re: Performance of the listen command

Flemming Frandsen wrote:
> I cache a lot of data in the application, to invalidate that cache I
> have triggers that use notify to let new transactions eject the objects
> from the cache.
>
> My problem with listen is that when I start a new connection I run a
> listen command for each of my tables, that loop takes around 10 seconds
> to complete and I have around 150 tables.

Do you regularly vacuum the pg_listener table?

> The strange thing is that just about any query runs in 1-4ms, but the
> listen command, which shouldn't even have to touch the disk takes around
> 60ms.

Actually, it does write to disk, because the listen information is kept
on a table.

--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.