Re: CURSOR_SHARING=SIMILAR + ODBC May Cause Problems
- From: rjamya <rjamya@xxxxxxxxx>
- To: Ethan.Post@xxxxxx
- Date: Tue, 2 Aug 2005 14:36:38 -0400
what happens if you changed cs=force?
Raj
On 8/2/05, Post, Ethan <Ethan.Post@xxxxxx> wrote:
>
> Just wanted to share a situation I encountered last week at a site. User
> were complaining about performance in some conversion/testing environments.
> I noted that the conversion scripts were hard parsing 4000/minute on a 2 cpu
> box. I changed QUERY_REWRITE and CURSOR_SHARING to SIMILAR. Parsing dropped
> to low number but script writer called to complain about slowdown.
> Investigation showed that the hard parsing SQL looked like...
> select foo from table where ID=123456789;
> After parameter changes SQL looked like....
> select foo from table where substr(ID,:bind,:bind)=:bind;
> so basically after the change the index in ID was not used because of
> function but hard parse made SQL look great except and it used index.
> This was an ODBC application using pass-through to submit SQL to Oracle.
> Not sure of others have seen this sort of thing but would be happy to
> learn more.
>
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