Re: Transactions involving multiple postgres foreign servers, take 2

> I've attached the latest version patches. I've incorporated the review
> comments I got so far and improved locking strategy.

Thanks for updating the patch!
I have three questions about the v23 patches.

1. messages related to user canceling

In my understanding, there are two messages
which can be output when a user cancels the COMMIT command.

A. When prepare is failed, the output shows that
committed locally but some error is occurred.

```
postgres=*# COMMIT;
^CCancel request sent
WARNING: canceling wait for resolving foreign transaction due to user
request
DETAIL: The transaction has already committed locally, but might not
have been committed on the foreign server.
ERROR: server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.
CONTEXT: remote SQL command: PREPARE TRANSACTION
'fx_1020791818_519_16399_10'
```

B. When prepare is succeeded,
the output show that committed locally.

```
postgres=*# COMMIT;
^CCancel request sent
WARNING: canceling wait for resolving foreign transaction due to user
request
DETAIL: The transaction has already committed locally, but might not
have been committed on the foreign server.
COMMIT
```

In case of A, I think that "committed locally" message can confuse user.
Because although messages show committed but the transaction is
"ABORTED".

I think "committed" message means that "ABORT" is committed locally.
But is there a possibility of misunderstanding?

In case of A, it's better to change message for user friendly, isn't it?

2. typo

Is trasnactions in fdwxact.c typo?

3. FdwXactGetWaiter in fdwxact.c return unused value

FdwXactGetWaiter is called in FXRslvLoop function.
It returns *waitXid_p, but FXRslvloop doesn't seem to
use *waitXid_p. Do we need to return it?

Regards,
--
Masahiro Ikeda
NTT DATA CORPORATION