Re: 2-phase commit

Bruce Momjian wrote:
> I haven't seen any comment on this email.
>
> From our previous discussion of 2-phase commit, there was concern that
> the failure modes of 2-phase commit were not solvable. However, I think
> multi-master replication is going to have similar non-solvable failure
> modes, yet people still want multi-master replication.
>
> We have had several requests for 2-phase commit in the past month. I
> think we should encourage the Japanese group to continue on their
> 2-phase commit patch to be included in 7.5. Yes, it will have
> non-solvable failure modes, but let's discuss them and find an
> appropriate way to deal with the failures.

FWIW, Oracle 8's manual for the recovery of a distributed tx where the
coordinator never comes back on line is:

https://www.ifi.uni-klu.ac.at/Public/Documentation/oracle/product/8.0.3/doc/server803/A54643_01/ch_intro.htm#7783

"If a database must be recovered to a point in the past, Oracle's
recovery facilities allow database administrators at other sites to
return their databases to the earlier point in time also. This ensures
that the global database remains consistent."

So it seems, for Oracle 8 at least, PITR is the method of recovery for
cohorts after unrecoverable coordinator failure.

Ugly and yet probably a prerequisite.

Mike Mascari
mascarm(at)mascari(dot)com