I'm pretty sure the optimizer can pick up 1=1 anyway and ignore it as an always-true condition - so you get no benefit.
The most common cause I've seen for 1=1 is so when developers are building dynamic where-clause, they don't need to worry about adding 'where' versus 'and' to the sql string being constructed. hth connor --- "Hately, Mike (LogicaCMG)" <[EMAIL PROTECTED]> wrote: > Morning folks, > > the developers here are looking at a view with a > where clause which > specifies : > > WHERE 1=1 AND > ............... AND > ............... etc. > > I'd seen this used before as a way of tweaking the > RBO into certain > behaviours but it was years ago and my recollection > is very hazy. > The only explanation I've found so far is : > > "the 1=1 is in there to avoid doing repetitive index > scans for single > rowids, when the app "knows" the result set is going > to be manipulated > rowid's for a large subset of the table. I would > guess your DUAL/CBO example > had some similar effect." > > Is anyone familiar enough with this tweak to explain > it ? > > Cheers, > Mike > > PS Maybe it'll head off some replies if I make it > clear that this view > hasn't been generated by code so the "1=1" isn't an > accidental artifact It > was custom written and is definitely supposed to > have exactly this > structure. > > > > > > > > ******************************************************************************************** > E mail Disclaimer > > You agree that you have read and understood this > disclaimer and you agree to be bound by its terms. > > The information contained in this e-mail and any > files transmitted with it (if any) are confidential > and intended for the addressee only. If you have > received this e-mail in error please notify the > originator. > > This e-mail and any attachments have been scanned > for certain viruses prior to sending but CE Electric > UK Funding Company nor any of its associated > companies from whom this e-mail originates shall be > liable for any losses as a result of any viruses > being passed on. > > No warranty of any kind is given in respect of any > information contained in this e-mail and you > should be aware that that it might be incomplete, > out of date or incorrect. It is therefore essential > that you verify all such information with us before > placing any reliance upon it. > > CE Electric UK Funding Company > Lloyds Court > 78 Grey Street > Newcastle upon Tyne > NE1 6AF > Registered in England and Wales: Number 3476201 > > ******************************************************************************************** > > -- > Please see the official ORACLE-L FAQ: > http://www.orafaq.net > -- > Author: Hately, Mike (LogicaCMG) > INET: [EMAIL PROTECTED] > > Fat City Network Services -- 858-538-5051 > http://www.fatcity.com > San Diego, California -- Mailing list and web > hosting services > --------------------------------------------------------------------- > To REMOVE yourself from this mailing list, send an > E-Mail message > to: [EMAIL PROTECTED] (note EXACT spelling of > 'ListGuru') and in > the message BODY, include a line containing: UNSUB > ORACLE-L > (or the name of mailing list you want to be removed > from). You may > also send the HELP command for other information > (like subscribing). ===== Connor McDonald web: http://www.oracledba.co.uk web: http://www.oaktable.net email: [EMAIL PROTECTED] "GIVE a man a fish and he will eat for a day. But TEACH him how to fish, and...he will sit in a boat and drink beer all day" ________________________________________________________________________ Want to chat instantly with your online friends? Get the FREE Yahoo! Messenger http://mail.messenger.yahoo.co.uk -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: =?iso-8859-1?q?Connor=20McDonald?= INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
