dinesh salve <cooltodinesh@gmail.com> writes:
Hi,
>
> I am working on a feature in postgres_fdw extension to show plans used
> by remote postgresql servers in the output of the EXPLAIN command.
>
> I think this will help end users understand query execution plans used
> by remote servers. Sample output for table people where people_1 is
> local partition and people_2 is remote partition would look like
This looks nice! Especially for the people who want a FDW based sharding
cluster.
> I would like community inputs on below high level thoughts:
>
> 1. To enable this feature, either we can introduce a new option in
> EXPLAIN command e.g. (fetch_remote_plans true) or control this
> behaviour using a guc defined in postgres_fdw extension. I am more
> inclined towards guc as this feature is for extension
> postgres_fdw. Adding the EXPLAIN command option might force other FDW
> extensions to handle this.
+1.
> 2. For ANALYZE = false, the idea is that postgres_fdw would create a
> connection to a remote server, prepare SQL to send over connection and
> store received plans in ExplainState.
> 3. For ANALYZE = true, idea is that postgres_fdw would set a new guc
> over connection to remote server, remote server postgres_fdw would
> read this guc and send back used query plan as a NOTICE (similar to
> auto_explain extension does) with custom header which postgres_fdw
> extension understands. We also have an opportunity to introduce a new
> message type in the protocol to send back explain plans but it might
> look like too much work for this feature. Open to ideas here.
This generally looks good to me. Looking forward a patch for the
details.
--
Best Regards
Andy Fan
