Re: Date performance

["Brigitte Caura" <Caura@xxxxxxxxxxxxx>]

Hi Andy,

Another drawback of the Date-field story is the disk occupation.

We use packed decimal 4,0 for our date-fields (3,0 for month-fields) with
the "lousy" 0/1 indication for 19##/20## ever since 86 (that is 1986).

Users can put in any dates with year as 2 digits (which they actually
prefer) in a window till the current year plus 10, from the current year
minus 90.

No dossiers are ever created that will be valid in more than 10 years (the
law would have been changed 20 times by then); Dossiers have to be kept
legally for 30 years, so we have a few spare years in the past too.

It works without any problem, so why should we change. (just add 1900 for a
complete ISO date).

If one uses dates in a real life application it might occur (IMHO, the
opposite will never occur) that these dates are part of the file indexes.

So our base 'history' file of paiements (average on our systems of about
1000000 rcds, rcdlng about 100), has 5 date fields:
Date of paiement, month for which the paiement is valid, accountancy month
(different from the first two, law reasons), date of input, date of eventual
modification.
We need 6 indexes over the base file, which use 3 real accesspaths (AP
sharing 2 by 2).
Of cours 4 of the date fields are in them.

If we use Date-fields the physical file would be 10% larger, not that much,
but the logicals would be 60% larger, occupying far more place than the
original physical.

Since this is the base file in a relational data base, these keyfields also
are referenced in its (10) dependent files, with their logicals.

Our suppliers keep telling disks cost nothing, but when they come with their
disk upgrade bills, our boss can't make them remember their first statement
(we still can't put PCdisks in our AS400s).

PS: In test (V3R7) I created a file with the systemvalue date separator (for
date displaying) on the normal  '/'.
Believe it or not but that sign was put in every datefield in the physical
file, converting 4bytes packed dec. to 10 bytes  ??

Regards
Luc
-----Oorspronkelijk bericht-----
Van: Warren Andrew <awarren@ottaway.com>
Aan: 'MIDRANGE-L@midrange.com' <MIDRANGE-L@midrange.com>
Datum: donderdag 22 oktober 1998 22:04
Onderwerp: Date performance


>I'm throwing out a recent experience in hope it may help
>someone else:
>
>We recently Y2K remediated a report to use ISO dates. The
>pre-remediation
>performance was good. The remediated performance was not.
>
>The users melted the support line and threatened to storm
>the data center
>with torches and pitchforks. They needed these reports for
>upcoming meetings.
>


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