Re: Some vacuum & tuning help

On 5 Aug 2003 at 8:09, Jeff wrote:

> I've been trying to search through the archives, but it hasn't been
> successful.
>
> We recently upgraded from pg7.0.2 to 7.3.4 and things were happy. I'm
> trying to fine tune things to get it running a bit better and I'm trying
> to figure out how vacuum output correlates to tuning parameters.
>
> Here's the msot recent vacuum for the "active" table.  It gets a few
> hundred updates/inserts a minute constantly throughout the day.

I would suggest autovacuum daemon which is in CVS contrib  works for 7.3.x as
well.. Or schedule a vacuum analyze every 15 minutes or so..
>
> INFO:  Pages 27781: Changed 0, Empty 0; Tup 2451648: Vac 0, Keep 0, UnUsed
> 1003361.
>         Total CPU 2.18s/0.61u sec elapsed 2.78 sec.
>
> I see unused is quite high. This morning I bumped max_fsm_pages to 500000.
> If I'm thinking right you want unused and max_fsm to be closish, right?
> (Yesterday it was down around.. oh.. 600k?)
>
> I'm thinking vacuum full's may be in order. Which stinks because I was
> hoping to do away with the db essentially down for 10 minutes (includes
> all the db's on that machine) while it vacuum'd.

I think vacuum full is required.

> The upside is: it is performing great.  During the vacuum analyze I do get
> a few multi-second pauses while something occurs. I figured it was a
> checkpoint, so I bumped checkpoint_timeout to 30 seconds and wal_buffers
> to 128. (I'm just guessing on wal_buffers).

If it is couple of tables that are that heavily killed, I would suggest to a
pg_dump, drop table and reload table. That should take less time. Your downtime
might not be 10 minutes but more like 15 say. That's a rough estimate..

>
> Machine is weenucks 2.2.17 on a dual p3 800, 2gb ram, 18gb drive (mirrored).

You mean linux? I guess you need a kernel revision for a long time. How about
2.4.21?

> If you guys need other info (shared_buffers, etc) I'll be happy to funish
> them. but the issue isn't query slowness.. just want to get this thing
> oiled).

See if this helps..

Bye
 Shridhar

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