Message-ID: <53039D02.6010107@computer.org>
Date: Tue, 18 Feb 2014 09:48:50 -0800
From: David Wall <d.wall@computer.org>
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To: pgsql-performance@postgresql.org
Subject: Re: DB size and TABLE sizes don't seem to add up
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On 2/18/2014 12:34 AM, Heikki Linnakangas wrote:
> On 02/18/2014 12:14 AM, David Wall wrote:
>> I am running PG 9.2.4 and I am trying to figure out why my database size
>> shows one value, but the sum of my total relation sizes is so much less.
>>
>> Basically, I'm told my database is 188MB, but the sum of my total
>> relation sizes adds up to just 8.7MB, which is 1/20th of the reported
>> total.  Where is the 19/20th of my data then?  We do make significant
>> use of large objects, so I suspect it's in there.  Is there a relation
>> size query that would include the large object data associated with any
>> OIDs in those tables?
>
> You can use "select pg_total_relation_size('pg_largeobject')" to get 
> the total size of the large objects. Attributing large objects to the 
> tables that refer them is more difficult. For a single table, 
> something like this:
>
> select sum(pg_column_size(lo.data))
> from lotest_stash_values t, pg_largeobject lo
> where lo.loid = t.loid;
>
> Replace "lotest_stash_values" with the table's name and lo.loid with 
> the name of the OID column.

Thanks, Heikki.  It's generally even trickier for us because we have a 
blob table that other components use for storing 
large/binary/unstructured objects (the code handles 
compression/decompression and encryption/decryption options for us).  So 
those tables have an UUID that points to a row in that table that 
contains the actual LOID.  I'll use your technique to at least tell me 
the size for specific tables where I can build the query like you've 
described.


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