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Re: Index bloat problem?

From: Bill Chandler <billybobc1210(at)yahoo(dot)com>
To: Josh Berkus <josh(at)agliodbs(dot)com>
Cc: pgsql-perform <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Index bloat problem?
Date: 2005-04-21 17:38:55
Message-ID: 20050421173855.76286.qmail@web51410.mail.yahoo.com (view raw or flat)
Thread:
Lists: pgsql-performance
--- Josh Berkus <josh(at)agliodbs(dot)com> wrote:
> Bill,
> 
> > What about if an out-of-the-ordinary number of
> rows
> > were deleted (say 75% of rows in the table, as
> opposed
> > to normal 5%) followed by a 'VACUUM ANALYZE'?
> Could
> > things get out of whack because of that situation?
> 
> Yes.  You'd want to run REINDEX after and event like
> that.  As you should now.
> 
> -- 
> Josh Berkus
> Aglio Database Solutions
> San Francisco
> 

Thank you.  Though I must say, that is very
discouraging.  REINDEX is a costly operation, timewise
and due to the fact that it locks out other processes
from proceeding.  Updates are constantly coming in and
queries are occurring continuously.  A REINDEX could
potentially bring the whole thing to a halt.

Honestly, this seems like an inordinate amount of
babysitting for a production application.  I'm not
sure if the client will be willing to accept it.  

Admittedly my knowledge of the inner workings of an
RDBMS is limited, but could somebody explain to me why
this would be so?  If you delete a bunch of rows why
doesn't the index get updated at the same time?  Is
this a common issue among all RDBMSs or is it
something that is PostgreSQL specific?  Is there any
way around it?

thanks,

Bill

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Subject: Re: Index bloat problem?
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