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From: Nico Sabbi <nicola.sabbi@poste.it>
To: pgsql-performance@postgresql.org
Subject: Configuration tips for very large database
Date: Thu, 12 Feb 2015 23:25:54 +0100
Message-ID: <54DD2872.3070603@poste.it> (raw)
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Hello,
I've been away from  postgres for several years, so please forgive me if 
I forgot nearly everything:-)

I've just inherited a database collecting environmental data. There's a 
background process continually inserting records (not so often, to say 
the truth) and a web interface to query data.
At the moment the record count of the db is 250M and growing all the 
time. The 3 main tables have just 3 columns.

Queries get executed very very slowly, say 20 minutes. The most evident 
problem I see is that io wait load is almost always 90+% while querying 
data, 30-40% when "idle" (so to say).
Obviously disk access is to blame, but I'm a bit surprised because the 
cluster where this db is running is not at all old iron: it's a vmware 
VM with 16GB ram, 4cpu 2.2Ghz, 128GB disk (half of which used). The disk 
system underlying vmware is quite powerful, this postgres is the only 
system that runs slowly in this cluster.
I can increase resources if necessary, but..

Even before analyzing queries (that I did) I'd like to know if someone 
has already succeeded in running postgres with 200-300M records with 
queries running much faster than this. I'd like to compare the current 
configuration with a super-optimized one to identify the parameters that 
need to be changed.
Any link to a working configuration would be very appreciated.

Thanks for any help,
   Nico


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