CHOOSE and SELECT in QTP

[Chris Sharman]

Is this RMS ? If not (Rdb or whatever) I've no useful knowledge.
Assuming RMS, is product_item the primary key, or alternate ?
If it's an alternative RMS key (not key 0), then reading a large number of
record by it will be very inefficient in terms of disk access, since it will
potentially re-read a whole data bucket for each record, and that could
well account for the poor performance. Sequential access (identical to access
by primary key) would read each data bucket once, then process all the records
in it.
If it's the primary key, I have no explanation and would be interested to hear
one, presumably from Cognos: I don't believe there would be a VMS/RMS related
explanation for this behaviour.
I'm not sure whether the Powerhouse dictionary primary key is necessarily the
same key as the RMS primary key.
"$ analyse/rms/fdl <datafile>" will generate a .fdl file describing (text) the
datafile and its keys - Key 0 is the primary.

Chris

>access product_table
>define product_choice char*1 = parm
>choose product_item (case of product_choice 		&
>			when "A" : "A@"			&
>			when "L" :  "B@@")
>Do processing ...
>
>In case of A was QTP in 5 minutes finished and in case of L in 92 minutes!
>92 minutes processing time seemed a bit strange. So I tried to campare it
>with a SELECT statement construction:
>
>access product_table
>define product_choice char*1 = parm
>select if product_item[1:1] <> "A"
>
>Do processing ...
>
>I was surprised when I saw a SELECT statement construction is almost 5 times
>faster then a CHOOSE statement; Qtp was in 16 minutes finished. I am aware
>of difference between "B@@" and "<> "A"". But I don't believe this is the
>only reason for such a big processing time difference. Or I am doing
>something wrong and saying something stupid?
>
>We are running on PH 7.10.F2 and OpenVMS for ALPHA V7.1-1H1
_______________________________________________________________________
Chris.Sharman@CCAgroup.co.uk		http://www.ccagroup.co.uk/
CCA Stationery Ltd, Eastway, Fulwood, Preston, Lancashire, PR2 9WS.


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