• Subject: Re: Query Optimizer
  • From: "R. Bruce Hoffman, Jr." <rbruceh@xxxxxxxxxxxxx>
  • Date: Wed, 10 Nov 1999 08:29:23 -0500

-----Original Message-----
From: Pete Hall <pbhall@execpc.com>
To: MIDRANGE-L@midrange.com <MIDRANGE-L@midrange.com>
Date: Tuesday, November 09, 1999 11:06 PM
Subject: Re: Query Optimizer


>
>That's what puzzled me. The reason was "4 - The cost to use this access
>path, as determined by the optimizer, was higher than the cost associated
>with the chosen access method." (which of course, was to build an access
>path, with an identical key.) The internal join key hypothesis seems
>reasonable.
>

Yeah, wild guess, but maybe the only way the optimizer saw to use that index
resulted in three physical I/Os instead of two. That would do it.

>>As for the messages about indexes needed, are you using the Database
monitor
>>(STRDBMON) output information? If you have V4R4, have you looked at the
>>database functions in OpsNav?
>
>STRDBMON sounds like something I need to know about. Thanks. We're
>currently at V4R3.

Well, at V4R3 you can order CA Express for V4R4 and the latest PTFs. This
gives you the OpsNav with the database and plug-in functionality. A lot of
work is being done in the database performance area in this area. Also,
checking another source, it appears that some, if not all, of the STRDBMON
SQL performance data is logged there in V4R3 as well.

A work of caution. The output from the database monitor is not for the faint
of heart. It is mostly a bunch of LONG character strings (flat file style)
that are defined by the codes in other fields. (yyyyyyeeeeeeccccchhhhh!)

The performance explorer plug-in for the OpsNav is supposed to have some of
the recommended queries against this data in the next release.

>Pete Hall
>pbhall@execpc.com
>http://www.execpc.com/~pbhall
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