Re: Lazy xid assignment V4 - Mailing list pgsql-patches

From Florian G. Pflug
Subject Re: Lazy xid assignment V4
Date
Msg-id 46DF28B9.9000406@phlo.org
Whole thread Raw
In response to Re: Lazy xid assignment V4  (Andrew Dunstan <andrew@dunslane.net>)
List pgsql-patches
Andrew Dunstan wrote:
> Florian G. Pflug wrote:
>>
>> So, in essence, you get the old pg_locks format back by doing
>> select l1.*, l2.transactionid as "transaction" from pg_locks l1,
>> pg_locks l2
>>   where l1.vxid = l2.vxid and l2.locktype = 'transaction'
>>   and l2.mode='exclusive' and l2.granted=true.
>>
>> Hm.. Maybe we should put that into the docs or into the release notes?
>>
> or make it a system view?
In that case we can just add "transaction" back to pg_locks, and save
the overhead of snapshotting the locking datastructures twice...

The reason against it was that we changed the semantics of the column -
if we just keep it there, people who use it might silently get wrong
results.

I think what we have now is fine for 8.3. Should we remove the
lock on the xid completely in 8.4, we'll have to revisit pg_locks
anway, since than the current views won't show a transactions xid at all.
But let's do that when 8.4 opens, and not now.

greetings, Florian Pflug


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