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radhakrishna commented on HHH-3031:
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When will this be incorporated, you donot allow interceptors for stateless session, and
then this is missing, come on guys :-?
Include "FOR READ ONLY" hint in non-locking DB2 statements
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Key: HHH-3031
URL:
http://opensource.atlassian.com/projects/hibernate/browse/HHH-3031
Project: Hibernate Core
Issue Type: Improvement
Components: core
Affects Versions: 3.2.5
Environment: 3.2.5, DB2/UDB 8.1+
Reporter: Steve Finch
Attachments: HHH-3031.patch
Original Estimate: 16h
Remaining Estimate: 16h
As per the DB2 documentation:
http://publib.boulder.ibm.com/infocenter/db2luw/v8/index.jsp?topic=/com.i...
The FOR READ ONLY clause indicates that the result table is read-only and therefore the
cursor cannot be referred to in Positioned UPDATE and DELETE statements. FOR FETCH ONLY
has the same meaning.
For result tables in which updates and deletes are allowed, specifying FOR READ ONLY (or
FOR FETCH ONLY) can possibly improve the performance of FETCH operations by allowing the
database manager to do blocking. For example, in programs that contain dynamic SQL
statements without the FOR READ ONLY or ORDER BY clause, the database manager might open
cursors as if the FOR UPDATE clause were specified. It is recommended, therefore, that the
FOR READ ONLY clause be used to improve performance, except in cases where queries will be
used in positioned UPDATE or DELETE statements.
A read-only result table must not be referred to in a Positioned UPDATE or DELETE
statement, whether it is read-only by nature or specified as FOR READ ONLY (FOR FETCH
ONLY).
The aforementioned improvement can be achieved by applying "FOR READ ONLY" when
other locking hints are not specified.
Patch to be uploaded soon.
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