Norbert --
As far as excluding certain columns from an insert/update statement, setting
the 'access' property on an field-descriptor to 'readonly' will cause that
field/column to be excluded from any insert/update statement that is
generated by ojb.
As far as getting OJB to issue an insert statement in lieu of an update
statement, the PersistenceBroker interface defines two methods for storing
objects:
public void store(Object obj);
public void store(Object obj, ObjectModification modification);
If you call the second version of this method and pass
org.apache.ojb.broker.util.ObjectModificationDefaultImpl#INSERT for the
'modification' argument, then ojb will issue an insert statement.
Ron Gallagher
Atlanta, GA
[EMAIL PROTECTED]
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]
Sent: Wednesday, October 08, 2003 10:13 AM
To: [EMAIL PROTECTED]
Subject: Choose columns to update
Hi all,
we use OJB1.0 RC4 against a DB2.
We want to tell OJB which columns should be included in the update statement
instead of updating all of them. The columns to update have the same name
and definition in all the tables.
Detailled information:
We have tables with many columns. Some columns hold only 'technical'
information like lastupdate timestamp and occur in each table. Whenever a
record is modified, we *insert* a new one and update these technical
attributes of the previously valid record (i.e. we are historizing the
changes). The tables also have many indexes. Therefore, updates on all
fields are costy (beside the bigger effort to build the query, higher
network traffic to the database and the obvious bigger overhead for the
database, it seems that these non-affected fields also cause costy index
calculations ond the database if incuded in the update).
What we actually need would be another descriptor for each table which
describes only this subset of columns to update. But this would cause many
more descriptors and classes. Because all information is already in the
objects and in the descriptors, we do not consider this as a solution.
The only thing we need is to tell OJB not to include every column in the
update statement (respectively which columns to include, similar to a
ReportQuery). How to do this?
Thanks in advance,
Norbert.
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