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This kind of delete shouldn't take long.

How long does it really take? Is there significant paging taking place?
Have you tried allocating more memory to this process? Perhaps prebring the
objects into main memory using SETOBJACC prior to DELETE?

Elvis

Celebrating 11-Years of SQL Performance Excellence on IBM i, i5/OS and
OS/400
www.centerfieldtechnology.com


-----Original Message-----
Subject: Deleting detail records with SQL

Hi list,

A coworker gave me the following SQL problem:

I need to erase all the detail from certain records from a header based
file. Something like:

Delete from DETAIL
Where exists( Select 1 from HEADER2 where DETAIL.invoice = HEADER2.invoice)

DETAIL has a lot more records than HEADER2. HEADER2 and DETAIL have indexes
by invoice.

So far, so good. Now, it seems that the system does read (explore) the
entire DETAIL file in the process (a quite lengthy process).

If I were to do this with RPG, I would reverse the file order. I would read
HEADER2, position DETAIL by key and, with an inside loop, delete all the
records where the invoice numbers coincide. Is there any way to emulate this
behavior with SQL?

Thanks,

Luis Rodriguez



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