Re: tracking commit timestamps

On Tue, Nov 25, 2014 at 11:19 PM, Alvaro Herrera
<alvherre(at)2ndquadrant(dot)com> wrote:
> Fujii Masao wrote:
>> On Tue, Nov 25, 2014 at 7:58 AM, Alvaro Herrera
>> <alvherre(at)2ndquadrant(dot)com> wrote:
>> >> And here is v10 which fixes conflicts with Heikki's WAL API changes (no
>> >> changes otherwise).
>> >
>> > After some slight additional changes, here's v11, which I intend to
>> > commit early tomorrow. The main change is moving the test module from
>> > contrib to src/test/modules.
>>
>> When I specify the XID of the aborted transaction in pg_xact_commit_timestamp(),
>> it always returns 2000-01-01 09:00:00+09. Is this intentional?
>
> Well, when a transaction has not committed, nothing is written so on
> reading we get all zeroes which corresponds to the timestamp you give.
> So yeah, it is intentional. We could alternatively check pg_clog and
> raise an error if the transaction is not marked either COMMITTED or
> SUBCOMMITTED, but I'm not real sure there's much point.
>
> The other option is to record a "commit" time for aborted transactions
> too, but that doesn't seem very good either: first, this doesn't do
> anything for crashed or for in-progress transactions; and second, how
> does it make sense to have a "commit" time for a transaction that
> doesn't actually commit?

What about the PREPARE and COMMIT PREPARED transactions?
ISTM that this feature tracks neither of them.

Regards,

--
Fujii Masao