Author: Robert Sample
Subject: Reply to: VSAM Space Allocation
Posted: Wed May 03, 2017 12:21 am (GMT 5.5)
I had a chance to test this. I created a 2-cylinder VSAM data set with 1000-byte records (1440 of them to be precise) and LISTCAT says I have an index with 3 levels. I then wrote a COBOL program to directly read 1000 records (from 441 to 1440) and then did a LISTCAT. The DATA component showed 1000 REC-RETRIEVED, as expected. The INDEX component showed 0 REC-RETRIEVED. I then changed the program to sequentially read 1000 records. Again, LISTCAT showed the expected 2000 REC-RETRIEVED for the DATA component (1000 direct reads and 1000 sequential reads) and the INDEX component showed 0 REC-RETRIEVED. I'll have to think about INDEX component REC-RETRIEVED and what it means some more.
But the answer to your question is now a definitive no, INDEX component REC-RETRIEVED is not related to the DATA component records retrieved.
_________________
TANSTAAFL
The first rule of code reuse is that the code needs to be worth re-using.
"We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil." -- Donald Knuth
Subject: Reply to: VSAM Space Allocation
Posted: Wed May 03, 2017 12:21 am (GMT 5.5)
| Quote: |
| 2. Records Retrieved for Index Component - A file read on DATA internally uses index to retrieve the record. Would this not update the Records Retrieved for Index Component? |
But the answer to your question is now a definitive no, INDEX component REC-RETRIEVED is not related to the DATA component records retrieved.
_________________
TANSTAAFL
The first rule of code reuse is that the code needs to be worth re-using.
"We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil." -- Donald Knuth