Re: probs with postgres - Mailing list pgsql-hackers

From Christopher Kings-Lynne
Subject Re: probs with postgres
Date
Msg-id 097701c2ef6d$d7b71990$6500a8c0@fhp.internal
Whole thread Raw
In response to probs with postgres  ("Christopher Kings-Lynne" <chriskl@familyhealth.com.au>)
Responses Re: probs with postgres  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
> "Christopher Kings-Lynne" <chriskl@familyhealth.com.au> writes:
> > I keep getting this:
> > 2003-03-20 08:15:49 WARNING:  Rel users_sessions: Uninitialized page
3195 -
> > fixing
>
> Hmm.  In 7.2.* I'd have said this was a known problem, but in 7.3.* it's
> not.  Want to dig into it?  This is what I know about the 7.2 problem:
>
> http://fts.postgresql.org/db/mw/msg.html?mid=1357214

OK, well I can tell you this at the moment:

1. We're running 7.3.2
2. We do an hourly VACUUM ANALYZE.  I do the odd VACUUM FULL (not on that
table) when I do large changes to tables.
3. users_sessions has heaps and heaps of reads and updates regular scan
deletes.  There are lots of SELECT..FOR UPDATEs done on the table
4. Table def:

usa=# \d users_sessions               Table "public.users_sessions"Column  |           Type           |
Modifiers
---------+--------------------------+------------------------sid     | character varying(32)    | not nullname    |
charactervarying(32)    | not nullval     | text                     |changed | timestamp with time zone | not null
default'now'uid     | integer                  | not null
 
Indexes: users_sessions_pkey primary key btree (sid, name),        users_sessions_cha_name_idx btree (changed, name),
    users_sessions_uid_idx btree (uid)
 

5. We have been having load and stability problems with our Postgres since
we released a massive upgrade to our website.  We did actually have one time
when Postgres crashed and the whole server rebooted when we got a bunch of
these:

Mar 20 09:25:54 serendipity /kernel: pmap_collect: collecting pv entries --
suggest increasing PMAP_SHPGPERPROC
Mar 20 09:27:09 serendipity /kernel: pmap_collect: collecting pv entries --
suggest increasing PMAP_SHPGPERPROC
Mar 20 09:28:29 serendipity last message repeated 2 times
Mar 20 09:29:42 serendipity /kernel: pmap_collect: collecting pv entries --
suggest increasing PMAP_SHPGPERPROC

So I reduced our shared buffers by a few thousand and I'm waiting on our
sysadmin to up the max pages per proc in the kernel.

Any ideas on anything I can look into?

Chris



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