Re: PGA_AGGREGATE_TARGET is another way to instability.
- From: J.Velikanovs@xxxxxxxx
- To: bdbafh@xxxxxxxxx
- Date: Thu, 7 Oct 2004 12:26:21 +0300
>I think that if your miss of sql in the shared pool is 10% that most
>statements that are not frequently executed will quickly be aged out
>and re-parsed during subsequent execution.
How about great guideline - parse ones execute many times.
In this context, the systems with good design which use bind variables are
more instable then others ;)
>How is this any different, if the bind variables used at parse (with
>cursor_sharing=SIMILAR) differ greatly from one execution to another,
>in terms of distribution?
And this is just begining of the list:
- PGA_AGGREGATE_TARGET
- bind variables peeking
- regular statistic gathering
...
...
...
More features we have (use), more instable our systems ;)
But there are some methods to get rid of it, or at least minimize impact I
suppose.
Jurijs
On 07.10.2004 03:05:28 oracle-l-bounce wrote:
>Jurijs,
>
>I think that if your miss of sql in the shared pool is 10% that most
>statements that are not frequently executed will quickly be aged out
>and re-parsed during subsequent execution.
>
>If then follows that this is only a concern if your application SQL
>code is nearly perfectly written and statements are not
>invalidated/aged out.
>
>Right.
>
>
>How is this any different, if the bind variables used at parse (with
>cursor_sharing=SIMILAR) differ greatly from one execution to another,
>in terms of distribution?
>
>Paul
>
>
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