Re: TRUTH about ROWID

At 02:00 PM 5/11/95 GMT, Bob Payne wrote: }[Charles Francis (ancrcs4!cfrancis@ancrcs4.attmail.com) wrote] } }> According to the Informix-On-line Dynamic Server Administrators Guide }> Version 7.1 Volume 2 page 43-35 rowid is still supported. As with earlier }> On-line releases rowid is a combination of a page identification number and }> the slot table entry number on the page for nonfragmented tables. Fragmented }> table may have rowid, but; it is implemented differently. } }> The Informix-On-line Dynamic Server Administrators Guide Version 7.1 }> Volume 1 page 16-20 explains the creation of rowid for fragmented tables. }> Rowid is may be created by use of any of the follow clauses: }> WITH ROWID in CREATE TABLE }> ADD ROWID in ALTER TABLE }> INIT in ALTER FRAGMENT }> Any of these implementations of ROWID on fragmented tables adds a 4 byte }> unique value the a table. } }> For more information I suggest finding access to the 7.1 manuals. } }I have not tested it, but I understand that when you do this, you are }actually creating a new column in the table. The rowid is *already* }there! The problem is that it is not unique within the fragmented }table. It *is* unique within the fragment, though. When you add the }rowid as mentioned above you are asking the engine to add a column }which is stored as a serial value. And, as we all know, you can }have only one serial column per table. Yes, this *does* count as the }serial column. } }Long story short: If you add the unique rowid, you cannot have an }additional serial column. This is the best and most accurate explanation I've heard yet. I guess it does pay the RTFM :-) Jon }Can anyone verify this? }+------------------------------------------------------------------------+ }| Bob Payne Internet: bobp@dev.dsc.dalsys.com | }| Systems Engineer : bpayne@netcom.com | }| Dallas Systems Corporation Voice: (214) 383-2238 | }+------------------------------------------------------------------------+ } } ================================================================== Jon Vemo Internet: jvemo@cyberspace.com Bothell, WA USA ------------------------------------------------------------------ Watch out for road-kill on the information superhighway....SPLAT!! ==================================================================