> -----Original Message----- > From: IBM Mainframe Discussion List > [mailto:[email protected]] On Behalf Of R.S. > Sent: Wednesday, April 14, 2010 12:13 PM > To: [email protected] > Subject: Re: Why a VSAM VRRN vs. KSDS with 4 byte key? > > W dniu 2010-04-14 16:18, McKown, John pisze: > > I'm just curious as to why IBM chose to create the VRRN > type of VSAM file. I understand a normal RRN (NUMBERED). In > both cases, the record is addessed by relative record number. > But I don't really see the need for a VRRN. Why not just have > a KSDS with a 4 byte key at offset 0? Is it to remove the > relative record number from the user record?And, I guess, so > that you can't change the "record number" by updating the > key. Just curious. > > What is VRRN? Do you mean RRDS with variable length records? > AFAIK it is > usually called vRRDS. In fact it *is* KSDS under the cover - it has > index, you specify freespace, etc. > Why vRRDS? Convenience? It's easier for existing apps. > > BTW: In the old days there were (were = support dropped) option in > COBOL allowing "emulation" of vRRDS on KSDS. I guess it was created > before vRRDS was created. In this case you had to define KSDS you all > the utilities except the application did treat the dataset as > regular KSDS. > > > -- > Radoslaw Skorupka > Lodz, Poland
Sorry. Yes - I meant vRRDS. And it is only convience, no other "special functionality" which I would not get with a 4 byte key? -- John McKown Systems Engineer IV IT Administrative Services Group HealthMarkets(r) 9151 Boulevard 26 * N. Richland Hills * TX 76010 (817) 255-3225 phone * (817)-961-6183 cell [email protected] * www.HealthMarkets.com Confidentiality Notice: This e-mail message may contain confidential or proprietary information. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. HealthMarkets(r) is the brand name for products underwritten and issued by the insurance subsidiaries of HealthMarkets, Inc. -The Chesapeake Life Insurance Company(r), Mid-West National Life Insurance Company of TennesseeSM and The MEGA Life and Health Insurance Company.SM ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
