Wyell's point is well taken re: performance hits on multiple sorted paths.
Image will have to do yeoman's work to sort each of the paths for each put,
delete or update.  Another caveat: by using CATALOGUE-NUMBER (the first item in
the entry) as a sort item, you implicitly designate the rest of the entry as an
"extended" sort path.  For every duplicate CATALOGUE-NUMBER entered into the
set, Image will use each item after CATALOGUE-NUMBER as part of the sort
sequence to determine the placement of the entry - i.e., the values of the
forward and backward chain pointers - and this can cause additional performance
impact.

Another side effect of implementing multiple sorts is that each sorted path will
likely not have its entries retrievable in contiguous blocks on disk, which will
increase the I/O necessary to do a chained retrieval on that path.  It's likely
that one or more of your search paths are already in this condition, but adding
sorts to each might exacerbate the issue.  For this reason, you might consider
sorting only the search path most frequently used by your application.
----
Lee Gunter                    The Regence Group
Supervisor, TRG HP/MPE Systems     503.375.4498
----
Opinions expressed are solely mine.





From: "Grunwald, Wyell C." <[log in to unmask]> on 03/08/2000 06:35 AM

Please respond to "Grunwald, Wyell C." <[log in to unmask]>


To:   [log in to unmask]
cc:    (bcc: Lee Gunter/BCBSO/TBG)

Subject:  Re: [HP3000-L] sorting image data




Certainly !  Just add the sort with ADAGER.  Since the sorted item
(Catalogue-number) is already a search item, this is not a problem.  If
Catalogue number was not a search item, this would be a problem because any
change programmatically to the catalogue number would require a put / delete
or critical item update.  Since this is already the case, adding a sort will
not cause a problem.  Beware that if you add the sort to all three items
below, that your performance on puts is going to slow way down if you have a
large number of detail dataset entries.

> -----Original Message-----
> From: bill grefe [SMTP:[log in to unmask]]
> Sent: Wednesday, March 08, 2000 9:26 AM
> To:   [log in to unmask]
> Subject:      sorting image data
>
> I have an image data set(see below). I would like to have this data
> returned
> from image sorted by
> Catalogue-number regardless of the search path used to find the data.  The
> programs that use this
> Data set are supplied by a third party and I have no access to them.
> Can I a) add a sort path with adager to catalogue-number (without breaking
> anything) or
>           b) sort the data with adager periodically

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