Are you a betting man?
-- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 עַם יִשְׂרָאֵל חַי ________________________________________ From: IBM Mainframe Assembler List <[email protected]> on behalf of Paul Gilmartin <[email protected]> Sent: Saturday, November 11, 2023 3:05 PM To: [email protected] Subject: Re: Is True Skip-Sequential Processing Possible with RECFM=FB,DSORG=PS? On Sat, 11 Nov 2023 08:59:07 -0500, David S. wrote: > ... . Sequential processing >*must* begin at specified starting point and there can be *no* reading of >any records prior to that point. > That sounds absurd. So if a block contains 10 records, you want to be able to read the last 5 with "*no* reading of" the first 5!? DASD don't work that way. >My gut feeling is it *cannot* be done - at least not with RECFM=FB. It >*might* be possible with RECFM=F, but efficiency would then be so >compromised it would probably outweigh any advantage from *true* >skip-sequential processing. How about UNIX files with RECFM=FB,FILEDATA=BINARY and using seek()? (But that still reads entire blocks into a buffer.) -- gil
