On Thu, Jun 6, 2013 at 6:28 PM, Greg Stark <stark@mit.edu> wrote:
> On Thu, Jun 6, 2013 at 1:39 PM, Heikki Linnakangas
> <hlinnakangas@vmware.com> wrote:
>> That will keep OldestXmin from advancing. Which will keep vacuum from
>> advancing relfrozenxid/datfrozenxid. Which will first trigger the warnings
>> about wrap-around, then stops new XIDs from being generated, and finally a
>> forced shutdown.
>>
>> The forced shutdown will actually happen some time before going beyond 2
>> billion XIDs. So it is not possible to have a long-lived transaction, older
>> than 2 B XIDs, still live in the system. But let's imagine that you somehow
>> bypass the safety mechanism:
>
> Ah, so if you do the epoch in the page header thing or Robert's LSN
> trick that I didn't follow then you'll need a new safety check against
> this. Since relfrozenxid/datfrozenxid will no longer be necessary.
Nothing proposed here gets rid of either of those, that I can see.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
