Re: should i expected performance degradation over time

On 09/10/2011 11:55 AM, Anibal David Acosta wrote:
> Sometimes I read that postgres performance is degraded over the time and something people talk about backup and
restoredatabase solve the problem. 
>
> It is really true?
>
> I have postgres 9.0 on a windows machine with The autovacuum is ON
>
> I have some configuration tables
>
> And a couple of transactional table.
>
> Transactional table has about 4 millions of rows inserted per day.
>
> In the midnight all rows are moved to a historical table and in the historical table rows are about 2 months, any
transactionolder than 2 months are deleted daily. 
>
> So, my question is, if Should I expect same performance over time (example: after 1 year) or should I expect a
degradationand must implements come technics like backup restore every certain time? 
>
> Thanks!!
>

Yes.  And no.  Things have changed over that last few versions.  In older version of PG I recall hearing about table
bloatproblems that were really bad, and backup/restore would fix it.  (Vacuum full would probably also have fixed it). 

"Vacuum full", in older versions was a last chance, bring a gun to a knife fight, nothing else has worked, fix table
bloatsolution.  Its not dis-similar from backup/restore. 

In newer versions of PG, autovacuum, vacuum and vacuum full are all much nicer and work better.  I really doubt you'll
needto resort to backup/restore to fix problems. 

Just remember:  the harder you hit a table, the less chance autovacuum will have to clean it up.  So you might need
manualvacuum.  autovacuum will cancel itself if the table is getting hit, where-as manual vacuum wont. 

Keeping on top of vacuum will keep your tables slim and trim.  If things get out of hand, they'll balloon into
problems. Vacuum full at that point should clean it up.  But, if you ignore the problem for two years, and have super
reallybad table bloat, well, maybe backup/restore is best. 


-Andy