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RE: SQL Cursor Questions(and query 400)


  • Subject: RE: SQL Cursor Questions(and query 400)
  • From: pytel@xxxxxxxxxx
  • Date: Fri, 19 Nov 1999 13:26:38 -0600

fixed

I may be wrong, but I seem to recollect hat Query will never use existing
access path - unless you point it directly to LF.

Best regards
    Alexei Pytel


Joel Fritz <JFritz@sharperimage.com> on 11/19/99 10:45:11 AM

Please respond to MIDRANGE-L@midrange.com

To:   "'MIDRANGE-L@midrange.com'" <MIDRANGE-L@midrange.com>
cc:
Subject:  RE: SQL Cursor Questions(and query 400)




Does this apply to Query400?  I know I've improved the batch performance of
queries dramatically by pointing them at an existing logical file when they
built an access path when pointed at an unkeyed physical.

> -----Original Message-----
> From: pytel@us.ibm.com [mailto:pytel@us.ibm.com]
> Sent: Thursday, November 18, 1999 6:25 PM
> To: MIDRANGE-L@midrange.com
> Subject: Re: SQL Cursor Questions
>
>
>
>
>
/*                SNIP                                             */
>
> SQL does not care, whether you address PF or LF - it will always use
> underlying data in the way it considers is most optimal.
> The difference between SQL in interactive session and SQL
> imbedded in a
> program is that optimization goals are slightly different.
> By defaut, interactive SQL is biased to returning first
> screenful of data
> as fast as possible, and imbedded SQL is geared to reduce
> entire processing
> time. This will explain why access path was used for
> interactive and not
> for batch - arrival access path may be more efficient if
> large subset of
> file records is selected.
>
>
> Best regards
>     Alexei Pytel
>
>
>
>
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