I remember when DB2 V4 and datasharing came out, they replaced the log RBA with a log record sequence number (LRSN) since the RBA could be duplicated if there are multiple systems each with its own log. The LRSN was a truncated (to 6 bytes) STCK value. Because a) the STCK isn't unique across a PLEX and b) the truncation, in a PLEX, DB2 had code to loop in the case of a duplicate LRSN. In addition, there is a macro STCKSYNC which does ensure uniqueness in a PLEX.
Wayne Driscoll Product Developer JME Software LLC NOTE: All opinions are strictly my own. -----Original Message----- From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf Of Edward Jaffe Sent: Friday, August 10, 2007 5:31 PM To: [email protected] Subject: Re: Another "why did they do it this way?" question - SMF time stamps McKown, John wrote: > Does anybody know why the people who designed SMF decided to encode the > date and time as FL4'hundredths of seconds after midnight' plus > PL4'0cyyddd'? Why not just put in the STCK value? STCK is guaranteed to > be unique on a system (and on a sysplex). Correction: STCK is *not* guaranteed unique across a sysplex. (You're probably thinking of STCKE.) Nevertheless, STCK would certainly provide more granularity than the existing 1/100 seconds. Of course, STCK values will wrap in September 2042. Nothing's perfect. -- Edward E Jaffe Phoenix Software International, Inc 5200 W Century Blvd, Suite 800 Los Angeles, CA 90045 310-338-0400 x318 [EMAIL PROTECTED] http://www.phoenixsoftware.com/ ---------------------------------------------------------------------- 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 ---------------------------------------------------------------------- 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
