Unfortuantely, this is also what I observed. If you use P6Spy, you will see that instead of generating JOIN in SQL statement, it creates seperate SQL statements which cause 1+n SQL statement execution (in 1:1 mapping). This works, but quite inefficient. I followed turtorial about JOIN, but no luck. Really hope some experts in the group can help.
----- Original Message ----- From: "Jason Woodard" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Friday, January 30, 2004 10:36 AM Subject: getCollectionByQuery() hung up in prefetchRelationship() > Hi, > > I am trying to use OJB to manage experiment data, and have started > with a naive approach where each experiment is a nested collection > eventually ending with variable/value pairs. Storing data works well, > and retrieving it using getCollectionByQuery() works eventually, but > is taking much longer than it should. > > When retrieving an experiment object, OJB invokes BasePrefetcher's > prefetchRelationship(), which makes a bunch of JDBC calls via > getCollectionByQuery(), which seems to return all the data OJB needs > to reconstruct the object. This takes about 10 seconds for my test > experiment (1000 runs, 25 observations each). prefetchRelationship() > then invokes associateBatched(), and stays there for another 20 > minutes with no further debug output, mainly creating Identity > objects. > > I'm wondering whether I've set up my schema in a way that's grossly > inefficient for OJB. (I've appended part of the repository.xml file > below.) I've thought about adding a reference from Value back to > Level, or using explicit PKs instead of anonymous ones, but haven't > tried either yet. > > FWIW, I'm using OJB 1.0.rc5 with the PB interface against a MySQL > database (3.0.9-stable driver). > > many thanks for any ideas, > > -j > > Jason Woodard > [EMAIL PROTECTED] > > > > <!-- Definitions for sim.harness.store.Level --> > <class-descriptor > class="sim.harness.store.Level" > table="LEVEL" > > > <field-descriptor > name="id" > column="ID" > jdbc-type="INTEGER" > primarykey="true" > autoincrement="true" > access="anonymous" > /> > <!-- foreign key for parent collection --> > <field-descriptor > name="seriesId" > column="SERIES" > jdbc-type="INTEGER" > access="anonymous" > /> > <field-descriptor > name="variableId" > column="VARIABLE" > jdbc-type="INTEGER" > access="anonymous" > /> > <reference-descriptor > name="variable" > class-ref="sim.harness.store.Variable" > auto-update="true" > auto-delete="true" > > > <foreignkey field-ref="variableId"/> > </reference-descriptor> > <field-descriptor > name="valueId" > column="VALUE" > jdbc-type="INTEGER" > access="anonymous" > /> > <reference-descriptor > name="value" > class-ref="sim.harness.store.Value" > auto-update="true" > auto-delete="true" > > > <foreignkey field-ref="valueId"/> > </reference-descriptor> > </class-descriptor> > > <!-- Definitions for sim.harness.store.Variable --> > <class-descriptor > class="sim.harness.store.Variable" > table="VARIABLE" > > > <field-descriptor > name="id" > column="ID" > jdbc-type="INTEGER" > primarykey="true" > autoincrement="true" > access="anonymous" > /> > <field-descriptor > name="name" > column="NAME" > jdbc-type="VARCHAR" > /> > </class-descriptor> > > <!-- Definitions for sim.harness.store.Value --> > <class-descriptor > class="sim.harness.store.Value" > > > <extent-class class-ref="sim.harness.store.AbstractValue"/> > </class-descriptor> > > <!-- Definitions for sim.harness.store.AbstractValue --> > <class-descriptor > class="sim.harness.store.AbstractValue" > > > <extent-class class-ref="sim.harness.store.IntValue"/> > <extent-class class-ref="sim.harness.store.DoubleValue"/> > <extent-class class-ref="sim.harness.store.BooleanValue"/> > <extent-class class-ref="sim.harness.store.StringValue"/> > </class-descriptor> > > <!-- Definitions for sim.harness.store.DoubleValue --> > <class-descriptor > class="sim.harness.store.DoubleValue" > table="DBL_VALUE" > > > <field-descriptor > name="id" > column="ID" > jdbc-type="INTEGER" > primarykey="true" > autoincrement="true" > access="anonymous" > /> > <field-descriptor > name="value" > column="VALUE" > jdbc-type="DOUBLE" > /> > </class-descriptor> > > <!-- etc. for other Value types --> > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
