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Message Posted: Thu, 05 Jan 2006 @ 17:03:26 GMT
Two possible changes to plans.
1) changing demographics of tables. However, this would make it run longer all the time.
2) collected stats being dropped and recreated so long running does not have proper information to run plan properly. Could also be caused by random amp samples expiring and getting collected differently next time around. I would suggest making sure you have proper statistics collected. Normally best choices are on columns used in join and in filters. Don't forget if your join between two tables is between 2 or more columns to collect them together even if they are not an index.
Collect stats on tablename column (col1, col2);
Another thing that might be confusing you is looking at explains in PMON.
If you are using PMON connected to a Teradata Manager Server, you will not always get the whole explain in Teradata manager version 7.0.0. Patch 220.127.116.11 corrects this problem. There is not a problem with PMON explains in any version when connecting directly to the database.
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