Re: openJPA generates select per row - impossible to use for simple select statements

[Craig L Russell]

Hi,






Thanks,

Craig

On Jul 15, 2009, at 12:19 AM, om wrote:

Could I ask again what the code is doing, following the query.getResultList() ? Where is the list of results being used? Are the results being serialized or detached?

Hi All!


help!


start generating query per object by primary key.

Code :

WHERE a.date = :date ");
     PersistenceProviderImpl impl = new PersistenceProviderImpl();
     OpenJPAEntityManagerFactory fac =

     OpenJPAEntityManager man = fac.createEntityManager();

     Query query = man.createQuery(queryBuf.toString());
     query.setParameter("date", reportDate);          
     List res = query.getResultList();


LOG TRACE


query "null"  

parameters: {date=java.util.GregorianCalendar[]}

t0.id, t0.version, t0.cur_code, t0.acc_date, t0.mask, t0.acc_name,
t0.acc_seq, t0.value FROM ACCOUNT t0 WHERE (t0.acc_date = ?)
[params=(Timestamp) 2009-07-03 00:00:00.0]

<t 1495423266, conn 1329090360> [78 ms] spent


<t 1495423266, conn 1329090360> executing prepstmnt 139855958 SELECT

[params=(long) 328]

openjpa.jdbc.SQL - <t 1495423266, conn 1329090360> [78 ms] spent

openjpa.jdbc.SQL - <t 1495423266, conn 1329090360> executing prepstmnt

WHERE t0.id = ? [params=(long) 329]

openjpa.jdbc.SQL - <t 1495423266, conn 1329090360> [78 ms] spent

openjpa.jdbc.SQL - <t 1495423266, conn 1329090360> executing prepstmnt

WHERE t0.id = ? [params=(long) 330]

openjpa.jdbc.SQL - <t 1495423266, conn 1329090360> [78 ms] spent
………………………………..



fields.

wrap works 1.5 sec. I’ve tried different query hints and a few openjpa
versions, but with no result.


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I’m new in openJPA, and didn’t manage to get over the problem with simple select statement for one object after a few days of investigation. Please For simple select from one object, OpenJPA ( same strategy for 1.0, 1.2.1, 2.0 ) fist generates right query to retrieve all rows and fields, and then StringBuffer queryBuf = new StringBuffer("SELECT a FROM Account AS a impl.createEntityManagerFactory("MainPersistence", System.getProperties()); [7/14/09 16:57:50:475 MSD] R 266 MainPersistence TRACE openjpa.Runtime - Query "SELECT a FROM Account AS a WHERE a.date = :date " is cached as target [7/14/09 16:57:50:475 MSD] R 266 MainPersistence TRACE openjpa.Query - Executing query: [SELECT a FROM Account AS a WHERE a.date = :date] with [7/14/09 16:57:50:475 MSD] R 266 MainPersistence TRACE openjpa.jdbc.SQL - <t 1495423266, conn 1329090360> executing prepstmnt 1388597956 SELECT [7/14/09 16:57:50:553 MSD] R 344 MainPersistence TRACE openjpa.jdbc.SQL - [7/14/09 16:57:50:553 MSD] R 344 MainPersistence TRACE openjpa.jdbc.SQL - t0.mask, t0.acc_name, t0.acc_seq, t0.value FROM ACCOUNT t0 WHERE t0.id = ? [7/14/09 16:57:50:631 MSD] R 422 MainPersistence TRACE [WebContainer : 2] [7/14/09 16:57:50:631 MSD] R 422 MainPersistence TRACE [WebContainer : 2] 646850190 SELECT t0.mask, t0.acc_name, t0.acc_seq, t0.value FROM ACCOUNT t0 [7/14/09 16:57:50:709 MSD] R 500 MainPersistence TRACE [WebContainer : 2] [7/14/09 16:57:50:709 MSD] R 500 MainPersistence TRACE [WebContainer : 2] 2146074602 SELECT t0.mask, t0.acc_name, t0.acc_seq, t0.value FROM ACCOUNT t0 [7/14/09 16:57:50:787 MSD] R 578 MainPersistence TRACE [WebContainer : 2] I need just list of detached objects to show it in grid. As it’s seen from log trace above, first query is enough to return all necessary objects and Why OpenJPA makes select per object after that? In this case simple code above works 37 seconds for retrieving 440 rows, since same jdbc select and

Craig L Russell
Architect, Sun Java Enterprise System http://db.apache.org/jdo
408 276-5638 mailto:craig.russ...@sun.com
P.S. A good JDO? O, Gasp!

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