Re: 8.2.4 serious slowdown

2008/1/10, Sim Zacks <sim@compulab.co.il>:
> I just upgraded my database server from 8.0.1 to 8.2.4
> Most things went very well, but I have a couple of queries that really slowed down with the new server.
> On 8.0.1 the query took less then 3 seconds to complete. On 8.2.4 the same query
> (I vacuumed the database before running the query) takes 60 seconds (10 minutes with Explain Analyze).
>
> The data is exactly the same on the 2 servers.
>
> To test for hardware differences, I loaded 8.0.11 onto a test server restored the database and ran the query.
> It took about 3 seconds. I then uninstalled postgresql and installed version 8.2.4 and restored the database
> and the query took about 60 seconds.
>
> On the 8.2.4 the CPU usage (as seen from top) goes up to about 97% for most of the 60 seconds of query.
> On 8.0.1, it didn't.
>
> I have the explain from both databases, if someone could help me walk through this, I would much appreciate it.

I have seen performance degradation at every new version since 7.3.
But now 8.3 is a complete disaster. It could be that my most expensive
query is just a corner case, but I don't believe it. I posted about it
but the whole thread disappeared from the archives. It can still be
found here:

http://archives.free.net.ph/message/20080105.004509.22be255d.es.html

Could you try 8.3 and see what happens? Keep the emails in case this
thread mysteriously disappears.

Regards, Clodoaldo Pinto Neto