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Re: Cursor Sharing| Soft Parsing

From: Suhen Pather <>
Date: Wed, 24 Jul 2002 22:43:21 -0800
Message-ID: <>


When coding you should parse once and execute the query many times rather than


It can be seen that a parse operation is done on each iteration through the loop. You may have avoided hard parsing but the program is still soft parsing. It has to check the shared pool for the query executed each time.

When coding u should rather  



So you would be parsing once and executing the query several times. Therefore reduction on latch contention which makes your application more scalable and hence better performance.

Check out,F4950_P8_CRITERIA:2588723819082,%7Bsoft%7D%20and%20%7Bparsing%7D

Also see Bjorn's paper on bind variables


> 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. I thought the
> processing of the statement to check permissions to be soft parsing. But,
> perhaps I'm misinformed.
> 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
> -----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
> So CURSOR sharing is not the "silver bullet" as one may expect.
> Regards
> Suhen
> On Thu, 25 Jul 2002 10:23, you wrote:
> > Mike,
> > What is the version of the database? Some versions of 8.1.7 had a few
> > bugs when this parameter was set to FORCE. I suggest searching Metalink.
> > But it does work as advertised in later releases. I would also recommend
> > reviewing Tom Kytes' book to read about his views in using this parameter
> > at the instance level (my boss is reading my copy, so I can't give you
> > page #s).
> >
> > - Kirti
> >
> > -----Original Message-----
> > Sent: Wednesday, July 24, 2002 6:08 PM
> > To: Multiple recipients of list ORACLE-L
> >
> >
> > Has anyone set Cursor Sharing to Force ?
> > I have a new system that we have to support
> > and there is alot literals filling up the
> > pool. I have never changed this parameter
> > from the default as many seemed to think the
> > jury was still out on it. However, due to
> > my situation, I figured I would try it out.
> > If anyone has any experience with this one
> > I would be curious to know what happened.
> >
> > Mike

Please see the official ORACLE-L FAQ:
Author: Suhen Pather

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Received on Thu Jul 25 2002 - 01:43:21 CDT

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