Re: Transactions involving multiple postgres foreign servers, take 2

> I've attached the new version patch set. 0006 is a separate patch
> which introduces 'prefer' mode to foreign_twophase_commit.

I hope we can use this feature. Thank you for making patches and 
discussions.
I'm currently understanding the logic and found some minor points to be 
fixed.

I'm sorry if my understanding is wrong.

* The v22 patches need rebase as they can't apply to the current master.

* FdwXactAtomicCommitParticipants said in 
src/backend/access/fdwxact/README
   is not implemented. Is FdwXactParticipants right?

* A following comment says that this code is for "One-phase",
   but second argument of FdwXactParticipantEndTransaction() describes
   this code is not "onephase".

AtEOXact_FdwXact() in fdwxact.c
    /* One-phase rollback foreign transaction */
    FdwXactParticipantEndTransaction(fdw_part, false, false);

static void
FdwXactParticipantEndTransaction(FdwXactParticipant *fdw_part, bool 
onephase,
    bool for_commit)

* "two_phase_commit" option is mentioned in postgres-fdw.sgml,
    but I can't find related code.

* resolver.c comments have the sentence
   containing two blanks.(Emergency  Termination)

* There are some inconsistency with PostgreSQL wiki.
https://wiki.postgresql.org/wiki/Atomic_Commit_of_Distributed_Transactions

   I understand it's difficult to keep consistency, I think it's ok to 
fix later
   when these patches almost be able to be committed.

   - I can't find "two_phase_commit" option in the source code.
     But 2PC is work if the remote server's "max_prepared_transactions" 
is set
     to non zero value. It is correct work, isn't it?

   - some parameters are renamed or added in latest patches.
     max_prepared_foreign_transaction, max_prepared_transactions and so 
on.

   - typo: froeign_transaction_resolver_timeout

Regards,

-- 
Masahiro Ikeda
NTT DATA CORPORATION