> Tatsuo Ishii <[EMAIL PROTECTED]> writes: > > With a help from Bruce, I wrote a small function which returns row > > locking information(see attached file if you are interested). > > Scanning the whole table seems a bit slow :-(
Yes, but I couldn't find any other way. > There is another possibility: in CVS tip, anyone who is actually blocked > on a row lock will be holding a tuple lock that shows exactly what they > are waiting for. For example: > > Session 1: > > regression=# begin; > BEGIN > regression=# select * from int4_tbl where f1 = 123456 for update; > f1 > -------- > 123456 > (1 row) > > Session 2: > > << same as above, leaving session 2 blocked > > > Session 1: > > regression=# select * from pg_locks; > locktype | database | relation | page | tuple | transactionid | classid > | objid | objsubid | transaction | pid | mode | granted > ---------------+----------+----------+------+-------+---------------+---------+-------+----------+-------------+------+-----------------+--------- > transactionid | | | | | 14575 | > | | | 14576 | 2501 | ShareLock | f > tuple | 48344 | 48369 | 0 | 2 | | > | | | 14576 | 2501 | ExclusiveLock | t > relation | 48344 | 48369 | | | | > | | | 14576 | 2501 | AccessShareLock | t > relation | 48344 | 48369 | | | | > | | | 14576 | 2501 | RowShareLock | t > transactionid | | | | | 14576 | > | | | 14576 | 2501 | ExclusiveLock | t > relation | 48344 | 10339 | | | | > | | | 14575 | 2503 | AccessShareLock | t > relation | 48344 | 48369 | | | | > | | | 14575 | 2503 | AccessShareLock | t > relation | 48344 | 48369 | | | | > | | | 14575 | 2503 | RowShareLock | t > transactionid | | | | | 14575 | > | | | 14575 | 2503 | ExclusiveLock | t > (9 rows) > > Session 2 (XID 14576) is blocked on session 1 (XID 14575) according to > the first row of this output. The second row shows the exact tuple > that it is after. > > This isn't an amazingly user-friendly way of displaying things, of > course, but maybe somebody could make a function that would show it > better using pg_locks as input. If I understand correctly, it seems the above method does show a locked row's TID which does not block someone else. That is a little bit different from what I expcted. > > I think it will be more usefull if actual xids are shown in the case > > "locker" is a multixid. It seems GetMultiXactIdMembers() does the > > job. Unfortunately that is a static funtcion, however. Is there any > > chance GetMultiXactIdMembers() becomes public funtion? > > No particular objection here. -- Tatsuo Ishii ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
