We have an UPDATE statement running in a large J2EE application that is getting blocked by some other statement. The update is using the primary key, so it should affect only one row. The isolation level being used in the application should be READ UNCOMMITTED, so it should only be another modification that is causing the block, but we can't see where.
We have obtained a report of All Blocking Transactions and this indeed shows a session blocking an update. Using the
DBCC INPUTBUFFER command shows the last statement executed by the blocking session, but this is an SELECT on another table than the UPDATE, so I think it can't be the cause. I presume it must be a statement earlier in the transaction.
At this point, my SQL Server knowledge runs dry, and I also have problems reproducing the issue; it occurs intermittently.
What steps should I know take to find the blocking statement?