From: Allen, Brandon <>
Date: Tue, 2 Nov 2010 13:05:34 -0700
Message-ID: <64BAF54438380142A0BF94A23224A31E11AEFCEB9C_at_ONEWS06.oneneck.corp>

Slide 36 seems to say that AWR is the same as statspack in that it is not based on "sampled data" like ASH - it is instead based on the delta between the data captured at the time of two snapshots. I would argue that these snapshots do still meet the definition of "sampled data", however I think what they're trying to say is that it's not limited to the data sampled by ASH.

I think there may be confusion between DBA_HIST_ACTIVE_SESS_HISTORY and AWR Snapshots. I'm not 100% sure my understanding is correct on this, but I think that what Niall is saying is correct for DBA_HIST_ACTIVE_SESS_HISTORY - it is a sampling of the sampling already done in ASH, however I believe the data used for AWR "snapshots" is completely separate and works just like Statspack did, so it can capture all SQL in the shared pool at the time of the snapshot if you tell it to - it is not limited to just the SQL sampled by ASH.

From: [] On Behalf Of Niall Litchfield

Probably my chief resource is Graham Wood's "Sifting through the Ashes" presentation from when 10g arrived. specifically p13

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Received on Tue Nov 02 2010 - 15:05:34 CDT

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