Re: Same statement in SQL plan cache multiple times??

The statements in question are being issues as only as part of an
interactive RPG program.

They are being prepared dynamically (yes I know this is open to
SQL injection), with literal comparison values. However, in the
SQL plan cache, the literals were replaced by parameter makers.
But given that many of the statement have a Total Times Run of
greater than 0, and there's not enough duplicates for every
dynamic run to result in a new entry in the plan cache, I'm
hoping somebody might know the circumstances in which a duplicate
entry is added to the plan cache.


On Wed, Apr 28, 2010 at 11:08 AM, CRPence wrote:

Charles Wilt wrote:

Trying to do some performance tuning, noticed that the SQL
plan cache often has the same statement shown multiple
times...which of course throws off the "Total Times Run".

I guess that would be the total times the [same] statement has been run _with the associated plan_ then.? :-)

Anybody know why this happens? or some way to work around
it? (he says as he looks at Elvis ;-)

Get all invocations of that statement to implement with the
same plan.? ;-)

Seriously though... I seem to recall seeing that, for example, the /same/ statement run interactive [*firstio implicit optimization] versus batch [with *allio implicit optimization]
would appear separately; the statements /explained/ with that
difference. For that scenario, adding the OPTIMIZE FOR ALL ROWS
clause on the SELECT request would make the one statement
appear only once, after having cleared the cache.