On 2019-10-23 14:49, jonatan.laurit...@yahoo.dk [firebird-support] wrote: > Sometimes I receive error message (during development and tests, of > course): > > deadlock > update conflict with concurret update > concurrent transaction number is 2926 > > Then I can find the other attachment with the long-running transaction > using: > > select a.mon$user, a.mon$attachment_name, a.mon$remote_address, a.* > from mon$transactions t > left join mon$attachments a on > (t.mon$attachment_id=a.mon$attachment_id) > where t.mon$transaction_id=2926 > > I would like to see the long-running statement as well, but > MON$STATEMENTS.MON$TRANSACTION_ID is mostly empty (null) for almost > all the records. > > Why is that? And is it possible to relate statements to the > transactions? > > Firebird 3.0.4.
As far as I know, a statement is only associated with a transaction if it is being executed or - for result set producing statements - has a cursor open. As soon as the execution is complete (or the cursor is closed), the statement is no longer associated with the transaction. The monitoring tables are a snapshot of activity (at the time the first query was run on a monitoring table in the current transaction), so if a statement is not executing (nor has an open cursor) at that time, it will not have a transaction id associated. Also be aware that long running transactions don't necessarily have long running statements, an update conflict means that a record being updated has uncommitted changes by another transaction. That modification could have completed some time ago, but the transaction itself is still open. Mark
