Re: Store FullTransactionId in TwoPhaseFileHeader/GlobalTransactionData

On Fri, Aug 2, 2019 at 1:38 AM vignesh C <vignesh21(at)gmail(dot)com> wrote:
> On Thu, Aug 1, 2019 at 5:36 PM Thomas Munro <thomas(dot)munro(at)gmail(dot)com> wrote:
> > On Thu, Aug 1, 2019 at 9:32 PM vignesh C <vignesh21(at)gmail(dot)com> wrote:
> > > There is also one more comment which is yet to be concluded. The
> > > comment discusses about changing subxids which are of TransactionId
> > > type to FullTransactionId type being written in two phase transaction
> > > file. We could not conclude this as the data is similarly stored in
> > > TransactionStateData.
> >
> > No comment on that question or the patch yet but could you please add
> > this to the next Commitfest so that cfbot starts testing it?
> >
> I have added it to the commitfest.

Thanks. This looks pretty reasonable to me, and I don't think we need
to worry about the subxid list for now. Here's a version I ran though
pgindent to fix some whitespace problems.

The pg_prepared_xacts view seems like as good a place as any to start
showing FullTransactionId values to users. Here's an experimental
patch on top to do that, introducing a new "xid8" type. After
pg_resetwal -e 1000000000 -D pgdata you can make transactions that
look like this:

postgres=# select transaction, gid from pg_prepared_xacts ;
transaction | gid
---------------------+-----
4294967296000000496 | tx1
(1 row)

--
Thomas Munro
https://enterprisedb.com