RE: CQE, SQE and QAQQINI

I know that Infor recommend changing the IBM i 6.1 setting for IGNORE_DERIVED_INDEXES back to *NO for BPCS / ERP LX installations. For these, the majority (75% +) of the indexes are logical files with Select/Omit criteria. Ignoring all the those indexes results in a slower sytem overall, even though the SQE engine is faster.


________________________________

From: midrange-l-bounces@xxxxxxxxxxxx on behalf of Jonathan Mason
Sent: Fri 28/08/2009 13:53
To: midrange-l@xxxxxxxxxxxx
Subject: CQE, SQE and QAQQINI



We have an SQL statement that uses the CQE and runs extremely slowly. In test I have created an Encoded Vector Index and also changed a local version of the QAQQINI file so that the IGNORE_DERIVED_INDEXES is set to *YES.

With these settings the SQL runs extremely fast, however the powers that be are nervous about changing a global setting that would potentially affect all SQL requests.

I've spent the morning talking to my friend, Google, and searching through the Midrange.com archives, and everything I have seen indicates that using the SQE is better than using the CQE.

With this in mind, are there any pitfalls in changing the IGNORE_DERIVED_INDEXES setting to *YES? Should we expect all SQL to run at least as fast as does currently or is there a risk that some SQL processes could run slower?

Thanks in advance

Jonathan



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