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To: pgsql-performance@postgresql.org, Landreville
	<landreville@deadtreepages.com>
Subject: Re: Calculating 95th percentiles
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> Any time the volume tables are queried it is to calculate the deltas
> between each in_octets and out_octets from the previous row (ordered
> by timestamp). The delta is used because the external system, where
> the data is retrieved from, will roll over the value sometimes.  I
> have a function to do this calcuation:

Would it be possible to do this when inserting and store the deltas  
directly ?