Ian D. Bjorhovde wrote:
> ----- Original Message -----
> From: "Juan Lanus" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Wednesday, March 21, 2001 9:02 AM
> Subject: Re: DB2EUG: Overhead for Dynamic SQL in UDB/AIX?
>
>
>
>> Hi, Bill
>>
>> Please let me throw two ideas I'm sure you are already aware of:
>>
>> 1- DB2 caches dymanic SQL statements. The great advantage of those
>> parameter markers is that they help the optimizer to recognize repeating
>> statements even with different data.
>
>
> Juan,
>
> For the following two statements:
>
> update mytable set (a,b,c,d,e) = (1,2,3,4,5) where f = 1;
> update mytable set (a,b,c,d,e) = (6,7,8,9,0) where f = 2;
>
> Are you saying that, (without using parameter markers), DB2 should
> get a hit in the package cache for the second statement?
No, I think you have to use parameters. That each new statement has to
be textually identical to the cached one.
Also, I think that SQLs like "SELECT * FROM t WHERE k BETWEEN ? AND ?"
will be optimized each time, fortunately.
What I'm trying to communicate is that with a few changes, your app
might behave closer to a binded app.
By selecting the few most used sentences and "parameterizing" them.
Regards--
Juan Lanus
TECNOSOL
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