Does anyone know - I mean know - not guess - the performance saving in using Natural syntax STARTING FROM & TO versus STARTING FROM ENDING AT.
I incorrectly assumed that there would be one less L3 command issue by Natural to Adabas because Adabas now had the ending value.
However I see this behaviour:
ENDING AT syntax
L3 ISN123 Response Code 0
L3 ISN246 Response Code 0
L3 ISN789 Response Code 0
with Natural displaying ISN123 & ISN246.
L3 ISN123 response code 0
L3 ISN246 response code 0
L3 ISN246 response code 3
with Natural also displaying ISN123 & ISN246.
I had thought part of the saving was reducing Adabas call count by 1. Would have been useful in situation where:
READ (1 million)
READ(1 record - but with 2 L3s)
saving 1 million L3s on the inner READ. But no.
And what’s that all about with ISN246 returned with the third L3? TEST DBLOG shows the RB populated. Is that left-over from the previous call? I hope so. Otherwise Adabas has decompressed ISN246 for a second time.
My guess is that the saving is (potentially) a DATA block I/O (in the case where the third records is in another block). Also the saving should be in not decompressing into RB when adarsp=3. I had hoped the L3 would be on the 2nd record and had saved the interprocess communication for a redundant Adabas call.