Re: Logical Replication WIP

On Sat, Aug 6, 2016 at 2:04 AM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> On 5 August 2016 at 16:22, Andres Freund <andres(at)anarazel(dot)de> wrote:
>> On 2016-08-05 17:00:13 +0200, Petr Jelinek wrote:
>>> as promised here is WIP version of logical replication patch.
>>
>> Yay!
>
> Yay2
>

Thank you for working on this!

I've applied these patches to current HEAD, but got the following error.

libpqwalreceiver.c:48: error: redefinition of typedef ‘WalReceiverConnHandle’
../../../../src/include/replication/walreceiver.h:137: note: previous
declaration of ‘WalReceiverConnHandle’ was here
make[2]: *** [libpqwalreceiver.o] Error 1
make[1]: *** [install-backend/replication/libpqwalreceiver-recurse] Error 2
make: *** [install-src-recurse] Error 2

After fixed this issue with attached patch, I used logical replication a little.
Some random comments and questions.

The logical replication launcher process and the apply process are
implemented as a bgworker. Isn't better to have them as an auxiliary
process like checkpointer, wal writer?
IMO the number of logical replication connections should not be
limited by max_worker_processes.

--
We need to set the publication up by at least CREATE PUBLICATION and
ALTER PUBLICATION command.
Can we make CREATE PUBLICATION possible to define tables as well?
For example,
CREATE PUBLICATION mypub [ TABLE table_name, ...] [WITH options]

--
This patch can not drop the subscription.

=# drop subscription sub;
ERROR: unrecognized object class: 6102

--
+/*-------------------------------------------------------------------------
+ *
+ * proto.c
+ * logical replication protocol functions
+ *
+ * Copyright (c) 2015, PostgreSQL Global Development Group
+ *

The copyright of added files are old.

And this patch has some whitespace problems.
Please run "git show --check" or "git diff origin/master --check"

Regards,

--
Masahiko Sawada