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Re: Is Diskeeper Automatic Mode safe?

From: Greg Smith <greg(at)2ndquadrant(dot)com>
To: cb <cb(at)mythtech(dot)net>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Is Diskeeper Automatic Mode safe?
Date: 2009-11-17 10:33:07
Message-ID: 4B027BE3.1020505@2ndquadrant.com (view raw or flat)
Thread:
Lists: pgsql-performance
cb wrote:
> My understanding is, before I joined the company, they did an upgrade 
> from 7 on Linux to 8 on Windows and got bit by some change in PG that 
> broke a bunch of code. After that, they have just refused to budge 
> from the 8.0.4 version we are on and know the code works against.
Yes; that's one of the reasons there was a major version number bump 
there.  That's a completely normal and expected issue to run into.  A 
similar problem would happen if they tried to upgrade to 8.3 or later 
from 8.0--you can expect the app to break due to a large change made in 8.3.

Sounds to me like the app doesn't really work against the version you're 
running against now though, from the issues you described.  Which brings 
us to the PostgreSQL patching philosophy, which they may not be aware 
of.  Upgrades to later 8.0 releases will contain *nothing* but bug and 
security fixes.  The basic guideline for changes made as part of the 
small version number changes (8.0.1 to 8.0.2 for example) are that the 
bug must be more serious than the potential to cause a regression 
introduced by messing with things.  You shouldn't get anything by going 
to 8.0.22 but fixes to real problems.  A behavior change that broke code 
would be quite unexpected--the primary way you might run into one is by 
writing code that expects buggy behavior that then breaks.  That's not a 
very common situation though, whereas the way they got bit before was 
beyond common--as I said, it was expected to happen.

-- 
Greg Smith    2ndQuadrant   Baltimore, MD
PostgreSQL Training, Services and Support
greg(at)2ndQuadrant(dot)com  www.2ndQuadrant.com


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Subject: Performance regression 8.3.8 -> 8.4.1 with NOT EXISTS
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