Do I need to unload/reload the file?

[Chris Sharman]

You may find that a key with only a few values, with a lot of records having
each value, may give quite poor performance (on RMS). A single character key
would probably fall into this category, although you don't say how big the
file is - if it's of modest size it probably won't matter.
You may be able to alleviate that using the "null key" feature, to exclude
one value (typically the normal value) from the index altogether (although
then you won't be able to choose that value).

Regardless, if you're doing an RMS rebuild (as you'll need to, if it's RMS),
I'd recommend:

$ anal/rms/fdl <file>						! create <filename>.fdl
$ edit/fdl/granular=double/anal=<filename>/nointer <filename>	! tune
<filename>.fdl
$ edit/fdl/granular=double <filename>
... invoke the add_key script, and answer the questions ...
$ convert/fdl=<filename>/nosort <file> <newfile>
$ rename/inherit <newfile> <file>

This will give you a much better tuned file than the Powerhouse defaults.
I'd recommend doing all but the add_key part on a weekly or monthly basis or
so, depending on the volume of adds/updates, to all important data files,
and on an occasional basis to the PH dictionary files themselves.

Chris

> -----Original Message-----
> From: Hoppe, Eric EP [mailto:eric.hoppe@steelscape-inc.com]
> Sent: 15 March 2002 18:00
> To: mx% powerh-l@lists.swau.edu
> Subject: Do I need to unload/reload the file?
>
>
> Hi all-
>
> I am running PH 7.10G1 on OpenVMS 7.1 and have a simple question we have
> been discussing and thought to see what the pros say...
>
> If an element is changed to be a key, do I need to unload/reload the data?
> I know (of course) what needs to be recompiled.  Historically, when in
> doubt, we have just done the reload.  If we don't need to do the
> reload, we
> can make the change without taking the system down.  By changing the field
> to a key, we are not affecting the offset of the data which leads me to
> believe we do not need to reload the data.
>
> To be a bit more illustrative, I want to change cd-suppl-paint to be an
> alternate, repeating, ascending key.
> -- Record Contents --
>     Item                                 Type            Size  Occ  Offset
>     NO-PAINT-REF                         CHARACTER         10            0
>     .CD-GLOSS                            ZONED UNSIGNED     1            0
>     .CD-TY-PAINT                         CHARACTER          2            1
>     .CD-PAINT                            CHARACTER          1            3
>     .NO-PAINT                            ZONED UNSIGNED     5            4
>     .CD-SUPPL-PAINT                      CHARACTER          1            9
>
> Thanks-
>
> ---ehops
>
> Eric Hoppe
> Steelscape, Inc.
> Senior Systems Analyst
> Kalama, WA  USA
> 360.673.8247
>
>
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> Date: Fri, 15 Mar 2002 09:19:15 -0800
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