Re: Perfomance decreasing - Mailing list pgsql-general

From Allan Engelhardt
Subject Re: Perfomance decreasing
Date
Msg-id 3B798C23.502F4341@cybaea.com
Whole thread Raw
In response to Re: Perfomance decreasing  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-general
Tom Lane wrote:

> >> I'm  doing  vacuum  periodically  (once a hour), but perfomance
> >> still falls down.
>
> It sounds to me like you may be running into index growth problems.
> VACUUM is presently not good about shrinking indexes.

I always enjoy Tom's comments - he is the master of understatement and always helpful.

In this case, however, I think he may be understating too much.  I read the original question as "PostgreSQL is not
usefulfor production systems."  Call me melodramatic if you like: you are probably right. 

The point, I guess, is this: it would be really useful to have a document somewhere that honestly described the
limitationsof (the current version of) PostgreSQL.  Don't use inheritance, don't use on 24x7 systems, whatever.  It
doesn'thave to be fancy formatting, a brain-dump to a text file would be excellent....  (This is a hint, Tom et al!!
:-))

>  If you drop
> and recreate the indexes used by your most important queries, does
> the performance go back to where it was?

For what it's worth: I observed a similar issue and found that a dump and restore of all the databases helped.  I
haven'ttried just recreating the index.  I'll try it out and maybe post a test script to reproduce the issue.....
(where?)


    --- Allan.



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