Re: Need help understanding pg_locks

Bruce Momjian <bruce(at)momjian(dot)us> wrote:

> OK, so as I understand it, in pg_locks:
>
> Column | Type | Modifiers
> --------------------+----------+-----------
> locktype | text |
> database | oid |
> relation | oid |
> page | integer |
> tuple | smallint |
> virtualxid | text |
> transactionid | xid |
> classid | oid |
> objid | oid |
> objsubid | smallint |
>
> virtualtransaction | text |
> pid | integer |
> mode | text |
> granted | boolean |
>
> It is the last four that are related to the "locking entity".

> vaguely represented the locked object.

I think more accurately:

Information about the lock requester:

virtualtransaction, pid

Information about what is being locked:

database, relation, page, tuple, virtualxid, transactionid, classid,
objid, objsubid (where NULL means "not applicable to this lock)

Information about the lock itself:

locktype, mode, granted

-Kevin