Re: [hibernate-dev] lock timeout support
On Fri 01 Jun 2012 05:27:12 AM CDT, Strong Liu wrote:
Hi there,
I'm working on this
org.hibernate.ejb.test.lock.LockTest#testFindWithPessimisticWriteLockTimeoutException
test, it failed on lots of DBs
for now, I found:
sql server : supports nowait, but not other lock timeout value
DB2 : doesn't support either
sybase: doesn't support either
by "doesn't support" I mean, can't set this timeout from sql statement
level, but they do support set it as a DB global config.
Sybase at least supports it as a connection-level setting as well. Do
the rest? The idea being that we could set and reset that connection
setting as the means to specify lock timeout. Practically though that
means they would also have to expose a way to read the current setting
value so that we knew what to reset to.
so, I'm wondering if we could choose this way:
1. if DB supports both, then good
2. if DB supports nowait only, and lock timeout is set to nowait, then good
2.1 if lock timeout is set to 5 milliseconds, for example, then we setQueryTimeout(1) //
(locktimeout +500)/1000+1
I think with your 2.1 we just need to be careful when the user has
specified a query timeout already.
3. if DB doesn't supports either, then same as 2.1, use
java.sql.Statement#setQueryTimeout
Set to what? Just some really low number?
does this acceptable? or we just ignore lock timeout if the
underlying Db doesn't support it?
The only possible outcomes if we cannot apply the requested lock
timeout in any manner is to (a) error or (b) ignore. Ignoring makes
lock timeout more of a hint than a requirement. Thats the fundamental
question we need to answer here. Don't know the answer, just
re-stating the question.
--
steve(a)hibernate.org
http://hibernate.org