JPA Query does not contain any open resources so does not require a close.
Prepared statement caching in JEE is handled by the JEE DataSource. You can
configure this in your JEE server DataSource config. TopLink, and
EclipseLink (GFv3) also support prepared statement caching in JSE, see,
http://forums.oracle.com/forums/thread.jspa?threadID=670453&tstart=0
I'm not sure if this option was available in TopLink Essentials (GFv2). But
TopLink Essentials does use prepared statements, so when used with a
DataSource's statement caching the same benefit will be obtained.
In TopLink the JPA Query generated SQL is also cached. So if you re-execute
the same query it will not need to reparse the JPQL and generate the SQL.
The best solution is to use named queries, so the SQL will always be cached.
TopLink and EclipseLink also have a dynamic JPQL parse cache, that can avoid
the JPQL parse cost even with dynamic JPA queries, but this was not
available in TopLink Essentials.
Markus KARG-3 wrote:
>
> I am using JDBC for a long time, and I have been using other DBMS APIs for
> far longer time. In almost any of those APIs I had the possibility to open
> a "Prepared Statement", that will get reused internally by the driver (no
> more need to parse the SQL again in a loop -- just the parameter values
> will get send to the DBMS). This is a good performance tuning thing when
> doing things in a loop, but one must take good care to close the statement
> when done -- otherwise one might run out of statement handles soon (e. g.
> in SQLAnywhere the admin can set a maximum limit of e. g. 10 open
> statements per connection to find defective applications not closing
> correctly the handles).
>
> Now since a few months I am using JPA, and I am wondering why there is
> nothing like a Query.close() method. I am pretty sure that Oracle did it's
> best to improve performance, so I expect that a query actually internally
> is using a PreparedStatement instead of sending the same SQL string all
> the time. But how to handle the out-of-handles problem?
>
> How does TopLink know that my admin is not allowing more than 10 open
> handles?
>
> Or IS there some hidden Query.close() method that I just do not know?
>
> Thanks!
> Markus
>
-----
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http://wiki.eclipse.org/User:James.sutherland.oracle.com James Sutherland
http://www.eclipse.org/eclipselink/
EclipseLink , http://www.oracle.com/technology/products/ias/toplink/
TopLink
Wiki: http://wiki.eclipse.org/EclipseLink EclipseLink ,
http://wiki.oracle.com/page/TopLink TopLink
Forums: http://forums.oracle.com/forums/forum.jspa?forumID=48 TopLink ,
http://www.nabble.com/EclipseLink-f26430.html EclipseLink
Book: http://en.wikibooks.org/wiki/Java_Persistence Java Persistence
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