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Message Posted: Thu, 20 Jan 2005 @ 14:46:06 GMT


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Subj:		Re: Insert into empty table with statistics

From:		Dieter Noeth

David Wellman wrote:

If the target table is empty on a particular AMP then that AMP will use fast-path

If the target table is not empty on a particular AMP then that AMP will not use fast-path

Yes this means that some AMPs will use fast-path and some will not. I have never seen this documented in any manual

I thought the same, but once i ran some tests:

- delete all rows from a table

- insert select into that table

- check the size of the transient journal, ampusage.CPUTime per AMP

- insert a row into an empty table

- insert select into that table

- check the size of the transient journal, ampusage.CPUTime per AMP again

If Fast Path was used on a per AMP basis, only a single AMP should have used TJ and had significantly increased CPUTime, but it was for *all* AMPs.

Dieter


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