[Postgres-xc-general] About the commit d73ae5182149b08e0728edb96eee339e0c0498b7

[Michael P. <mic...@gm...>]

Hi all,

I have a couple of comments about the commit
d73ae5182149b08e0728edb96eee339e0c0498b7 (Mirroring and XCM support).
There are a couple of information that is not written in the commit message
so as not to make it too long.
Mirroring supports:
- SELECT queries
- DML queries
- DDL
- Multi INSERT
- EXECUTE DIRECT has been modified to be able to target directly mirrors.
- Cursor fetch

For instance,
EXECUTE DIRECT on node 1/2 'select * from foo';
will send the query directly to datanode 1, mirror 2.
The only addition consists of the format datanode_id/mirror_id when parsing
the query string.

There are still a couple of issues with this feature:
- Row count for DML is not correct (bug 3185566)
- CURRENT OF is not supported yet.
Those issues would need a better way to index datanode numbers than the one
used now,
more or less the same way that is used for EXECUTE DIRECT based on
PGXCMirror nodes.

Regards,
-- 
Michael Paquier
http://michaelpq.users.sourceforge.net