Bernt M. Johnsen wrote:
Daniel John Debrunner (JIRA) wrote (2006-11-28 11:25:22):
[ http://issues.apache.org/jira/browse/DERBY-2060?page=comments#action_12454083 ]
Daniel John Debrunner commented on DERBY-2060:
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Connection.setTransactionIsolation() does commit the transaction
with the embedded driver unless the isolation is being changed to
the current isolation, ie. no change.
Yes, you're right (but the netowrk driver will *always* commit). The
problem is that a user may accidentally change the behaviour of his
program just by altering a setTransactionIsolation call, even if the
change in isolation level per se should not cause a change.
I think that we should not allow setTransactionIsolation on an active
transaction, and make Derby conformant with SQL 2003, where you're not
allowed to do SET TRANSACTION if there is an active transaction or if
there are any open holdable cursor from the last transaction (See
section 16.2)
Do you mean SET ISOLATION rather than SET TRANSACTION? (I don't have
access to the SQL 2003 standard.)
It seems that we have two issues here.
1) The desired change in SET ISOLATION behavior should be in a separate
bug -- maybe DERBY-2064, which is not a documentation bug and where it
is not clear right now what the needed change is, or maybe a new bug
with the broader change.
2) Should we document the current behavior in the meantime, while
waiting for the fixes? If so, what exactly is the current behavior? This
is my understanding -- please correct as necessary:
If there is an active transaction, the network client driver always
commits the active transaction if either SET ISOLATION or
Connection.setTransactionIsolation is called. It does this even if the
statement or method call does not actually change the isolation level
(that is, if it sets the isolation level to its current value). The
embedded driver also always commits the active transaction if SET
ISOLATION is called. However, if Connection.setTransactionIsolation is
called, the embedded driver commits the active transaction only if the
call to Connection.setTransactionIsolation actually changes the
isolation level.
Thanks,
Kim
(The JDBC spec and Javadoc (both 1.4 and 1.6) says it's implementation
defined, while the tutorial, 3rd ed., says that the call *will*
commit. [sigh!])
SET CURRENT ISOLATION in ref.man refers java.sql.Connection.setTransactionLevel
instead of java.sql.Connection.setTransactionIsolation
--------------------------------------------------------------------------------------------------------------------------------------
Key: DERBY-2060
URL: http://issues.apache.org/jira/browse/DERBY-2060
Project: Derby
Issue Type: Bug
Components: Documentation
Reporter: Bernt M. Johnsen
Assigned To: Kim Haase
Attachments: DERBY-2060.diff, DERBY-2060.zip
On SET CURRENT ISOLATION statement in the Derby refernce manual:
"Issuing this command commits the current transaction, which is consistent with the
java.sql.Connection.setTransactionLevel method."
The correct method name is java.sql.Connection.setTransactionIsolation
(java.sql.Connection.setTransactionLevel does not exist)
BTW: setTransactionIsolation will commit the current transaction if called in
the client driver but not in the embedded driver. See DERBY-638
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