Tom Lane wrote:
> Florian Pflug <f...@phlo.org> writes:
> > On Jul11, 2011, at 05:47 , Bruce Momjian wrote:
> >> Thank you.  I think my confusion is that virtualtransaction is the lock
> >> holder/waiter, and the other two are actual locks.  The attached doc
> >> patch clarifies that.  I had actually realized this a few weeks ago and
> >> forgot, meaning this is pretty confusing.
> 
> > For consistency, I guess it should say "lock object" instead of simply
> > "object" the description of all the columns up to (and including)
> > "objsubid", not only those of "virtualxid" and "transactionid".
> 
> Yeah, I think this patch is going in the wrong direction altogether.
> It would be better to modify the description of virtualtransaction
> and pid to say that those are the "locking" entity.

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".  I don't
see a way of improving the description of the last four columns:

        http://developer.postgresql.org/pgdocs/postgres/view-pg-locks.html

What was unclear to me was that the earlier columns (illogically)
vaguely represented the locked object.

-- 
  Bruce Momjian  <br...@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + It's impossible for everything to be true. +

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