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Message Posted: Thu, 09 Jan 2003 @ 10:54:49 GMT

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Subj:   Session Mode (ANSI v Teradata)
From:   Anomy Anom

<-- Anonymously Posted: Wednesday, January 08, 2003 18:15 -->

When we first installed our Teradata system, we was recommended by NCR to use ANSI Mode rather than Teradata Mode.

We decided to leave the system in Teradata Mode, but specifically set ANSI mode when executing BTEQ scripts and accessing the system via Cognos through ODBC.

We have noticed alot of differences in terms of explain plans, execution times, some of which we have reported, and fixes have been written.

We was assured that there are no differences between the two, in terms of performance. SQL in both modes should generate the same execution plan.

We have consistantly found this to be not true. With some SQL executing in seconds in one mode, but taking minutes in the other mode.

We do however get a better consistance of good execution plans from our Cognos generated SQL within ANSI mode rather than Teradata mode, however when ANSI mode is poor performing, it is not just a little bit poor performing, but very poor performing, some times 10-100x difference.

Talking with other Teradata users, they all recommend Teradata mode, and would not touch ANSI mode.

Has anyone else had the same types of problems?

Would you make use of ANSI mode?

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