Re: "Multiple statements are an issue with pgPool-II in its replication mode" again

Hi,

> Can you give us a complete example of this issue? if this is something
> you get when modifying an object using pgAdmin's UI, it'll be hard to
> do. pgAdmin relies a lot on multi-statements. But probably we can figure
> a way to do this. I kind of did this for this patch :
>
> http://git.postgresql.org/gitweb?p=pgadmin3.git;a=commit;h=8dc53145d50ed2f65a112700c1390db79120f6d7

The example to show below is not *complete*, but will be useful.

the feature (summary):

* Pgpool-II replication does not keep OID same between backend nodes.
(pgpool-II master-slave mode + slony-I also does not keep OID)

* Pgpool-II run multi-statements query at all nodes.
(Pgpool-II run simple SELECT at one of nodes)

* Pgpool-II cause an error (or failover judgement) by difference in:
- number of return rows
- number of update, delete rows
- Error or not

example (SQL at pgpool-II replication mode):

"Set some_guc TO 'xx'; SELECT * FROM pg_enum ORDER BY oid"
--> OK (run at all nodes, but it is unnecessarily; no harm)

"SELECT * FROM pg_enum ORDER BY oid"
--> OK

"Set some_guc TO 'xx'; SELECT * FROM pg_enum WHERE oid = 12345"
--> NG (oid differ cause mismatch on number of return rows anytime)

"SELECT * FROM pg_enum WHERE oid = 12345"
--> OK (but in case pgpool-II "load balance mode",
cause inconsistent output sometime)

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harukat(at)sraoss(dot)co(dot)jp SRA OSS, Inc http://www.sraoss.co.jp