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The issue with SETLL vs CHAIN is that SETLL doesn't lock the database record when you're just checking to see if the record exists. However, the new N (no lock) operation extender (that's the old "Half Adjust" column to you RPGII coders) essentially provides a way to avoid locking the db record. CHAIN is a direct-to-the-record process, whereas SETLL does (metaphorically speaking) a CHAIN with no lock, followed by a READP. This allows the next READ to access the next record in the file. (It doesn't actually do a READP, folks, so don't write letters <g>). So I suppose there is a little performance difference in that CHAIN with No lock does fewer things. But hey, I don't believe in rules that say "This is always better than that". If SETLL does the job the right way for the task at had, USE IT! If CHAIN with No lock works for you, then use that. In either case, you probably won't shave enough off a job that runs 2 or 3 hours to notice. Bob Cozzi -----Original Message----- From: Wayne Achenbaum [SMTP:wache@vicomnet.com] Sent: Tuesday, May 20, 1997 12:37 PM To: MIDRANGE-L@midrange.com Subject: CHAIN versus SETLL The issue with SETLL vs CHAIN is that SETLL doesn't lock the database record when you're just checking to see if the record exists. However, the new N (no lock) operation extender (that's the old "Half Adjust" column to you RPGII coders) essentially provides a way to avoid locking the db record. CHAIN is a direct-to-the-record process, whereas SETLL does (metaphorically speaking) a CHAIN with no lock, followed by a READP. This allows the next READ to access the next record in the file. (It doesn't actually do a READP, folks, so don't write letters <g>). So I suppose there is a little performance difference in that CHAIN with No lock does fewer things. But hey, I don't believe in rules that say "This is always better than that". If SETLL does the job the right way for the task at had, USE IT! If CHAIN with No lock works for you, then use that. In either case, you probably won't shave enough off a job that runs 2 or 3 hours to notice. Bob Cozzi I recently attended the April Common in Boston. A junior programmer I work with took an intermediate Rpg class. The instructor taught the class that a setll was more expensive than a chain on a no hit condition. Can anyone back this up or refute this? Please state some reasoning behind the answer to this question. I was always taught to use a setll, not a chain when record existence was the only task at hand. -- Wayne Achenbaum Slomin's Inc. 125 Lauman Lane Hicksvlle, NY 11801-1886 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * This is the Midrange System Mailing List! To submit a new message, * * send your mail to "MIDRANGE-L@midrange.com". To unsubscribe from * * this list send email to MAJORDOMO@midrange.com and specify * * 'unsubscribe MIDRANGE-L' in the body of your message. Questions * * should be directed to the list owner / operator: david@midrange.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
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