Archives of the TeradataForum

Message Posted: Thu, 08 Sep 2011 @ 07:43:30 GMT

	<Prev	Next>		<<First	<Prev	Next>	Last>>

Check out KAP1AF15A if you have access to TD@YS. It basically says..

In general statistics is not dependent on system configuration so it's not necessary to refresh statistics after system expansion.

However starting TD12, AVERAGE AMP RPV is collected on NUSI column. Since this is AMP local information, if statistics is collected on NUSI, it is now recommended to refresh after system expansion.

This is also true in case data is archived and restored on systems with different number of amps.

Statistics should be refreshed when a table has been extensively modified (more than 10% of the rows added or deleted) since statistics were last collected.

Overall average of the average rows per value from each AMP.

Note that the system collects Average AMP Rows Per Value statistics only for NUSI columns. The value is used to improve nested join costing.

If this is not a NUSI column, the system reports a null.

- Alpesh

	<Prev	Next>		<<First	<Prev	Next>	Last>>