I'll admit I'm gullible, and I do look to you as more knowledgeable than me about internals.
On the other hand, I'm a born and bred New York City girl.... and I've never "bought a bridge" yet. guess I'll have to live with "because" as the answer Get on with you.... :) Rachel --- Connor McDonald <[EMAIL PROTECTED]> wrote: > Its three because the mapping of the memory structures > to the pga is most efficient when the hashing function > involved uses the lowest prime that is not a power of > two. > > (long pause) > > ...and if you believe that, you'll believe anything > :-) > > hee hee hee > > Connor > > --- Rachel Carmichael <[EMAIL PROTECTED]> wrote: > > Connor, > > > > Well, technically that answers the "why"... with > > Oracle's "because I > > said so" :) > > > > the REAL question is why 3 and not 2 or 4 or 10 > > or..... ? > > > > Rachel > > > > > > --- Connor McDonald <[EMAIL PROTECTED]> wrote: > > > "RTM" :-) > > > > > > Performance Guide 9.2 > > > > > > "Caching Session Cursors > > > > > > (blah blah blah) > > > > > > Oracle checks the library cache to determine > > whether > > > more than three parse requests have been issued on > > a > > > given statement. > > > > > > (more blah blah blah)" > > > > > > hth > > > connor > > > > > > > > > --- [EMAIL PROTECTED] wrote: > I wasn't > > aware > > > of it requiring three calls before > > > > being useful. > > > > > > > > Why is that? > > > > > > > > Jared > > > > > > > > > > > > > > > > > > > > > > > > "Cary Millsap" <[EMAIL PROTECTED]> > > > > Sent by: [EMAIL PROTECTED] > > > > 07/25/2002 07:58 AM > > > > Please respond to ORACLE-L > > > > > > > > > > > > To: Multiple recipients of list > > ORACLE-L > > > > <[EMAIL PROTECTED]> > > > > cc: > > > > Subject: RE: Cursor Sharing| Soft > > > > Parsing > > > > > > > > > > > > Well, three times, right? I think it takes three > > > > parse calls before > > > > session_cached_cursors begins to help. But 3 is > > > > still O(1). Once per > > > > call is O(#executions). > > > > > > > > > > > > Cary Millsap > > > > Hotsos Enterprises, Ltd. > > > > http://www.hotsos.com > > > > > > > > Upcoming events: > > > > - Hotsos Clinic, Jul 23-25 Chicago > > > > - Miracle Database Forum, Sep 20-22 Middlefart > > > > Denmark > > > > - 2003 Hotsos Symposium on OracleR System > > > > Performance, Feb 9-12 Dallas > > > > > > > > > > > > > > > > -----Original Message----- > > > > Still > > > > Sent: Thursday, July 25, 2002 2:38 AM > > > > To: Multiple recipients of list ORACLE-L > > > > > > > > On Wednesday 24 July 2002 22:08, MacGregor, Ian > > A. > > > > wrote: > > > > > Please define soft parsing. Oracle needs to > > check > > > > that the user > > > > > submitting a SQL statement has permissions to > > run > > > > it. It has to do > > > > this > > > > > every time a statement is run, bind variables > > or > > > > not. > > > > > > > > No, code that uses bind variables need only > > parse > > > > SQL statements > > > > once if session_cached_cursors is set. Further > > > > executions of the same > > > > SQL don't require a hard or soft parse. > > > > > > > > Jared > > > > > > > > > When "cursor-sharing" converts a statement to > > use > > > > bind variables it > > > > would > > > > > save on hard parsing, if a match were found > > the > > > > pool; also, it could > > > > lessen > > > > > the number of statements present in the pool. > > > > > > > > > > Ian MacGregor > > > > > Stanford Linear Accelerator Center > > > > > [EMAIL PROTECTED] > > > > > > > > > > -----Original Message----- > > > > > Sent: Wednesday, July 24, 2002 9:23 PM > > > > > To: Multiple recipients of list ORACLE-L > > > > > > > > > > > > > > > Mike, Kirti, > > > > > > > > > > Try page 441 > > > > > > > > > > CURSOR_SHARING=FORCE does improve badly > > written > > > > applications that use > > > > lots > > > > > of literals. > > > > > However coding should be done using bind > > variables > > > > in almost all > > > > occasions. > > > > > > > > > > CURSOR_SHARING=FORCE reduces the hard parsing. > > > > > > > > > > What CURSOR_SHARING=FORCE does is rewrites all > > > > queries to use bind > > > > > variables before parsing. > > > > > > > > > > eg. select ename from emp where empno = 10; > > > > > rewritten as > > > > > select ename from emp where empno =:SYS_B_0 > > > > > or in 8.1.6 , 8.1.7 > > > > > select name from emp where empno =:"SYS_B_0" > > > > > > > > > > So it substitutes the literal with bind > > variables > > > > but incurs the cost > > > > of > > > > > soft parsing the statement. > > > > > Soft Parsing too frequently limits the > > scalability > > > > of applications and > > > > > sacrifices optimal performance which could > > have > > > > been achieved in the > > > > first > > > > > place if written using bind variables. > > > > > > > > > > Parse once and execute as many times as we > > like. > > > > > > > > > > Also check out Bjorn's paper on bind variables > > and > > > > cursor sharing at > > > > > > > > > > > > > > > http://technet.oracle.com/deploy/performance/pdf/cursor.pdf > > > > > > > > > > So CURSOR sharing is not the "silver bullet" > > as > > > > one may expect. > > > > > > > > > > Regards > > > > > Suhen > > > > > > === message truncated === __________________________________________________ Do You Yahoo!? Yahoo! Health - Feel better, live better http://health.yahoo.com -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Rachel Carmichael INET: [EMAIL PROTECTED] Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- 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).
