Re: [PATCH] Automatic HASH and LIST partition creation

https://commitfest.postgresql.org/32/2694/

I don't know what committers will say, but I think that "ALTER TABLE" might be
the essential thing for this patch to support, not "CREATE". (This is similar
to ALTER..SET STATISTICS, which is not allowed in CREATE.)

The reason is that ALTER is what's important for RANGE partitions, which need
to be created dynamically (for example, to support time-series data
continuously inserting data around 'now'). I assume it's sometimes also
important for LIST. I think this patch should handle those cases better before
being commited, or else we risk implementing grammar and other user-facing interface
that fails to handle what's needed into the future (or that's non-essential).
Even if dynamic creation isn't implemented yet, it seems important to at least
implement the foundation for setting the configuration to *allow* that in the
future, in a manner that's consistent with the initial implementation for
"static" partitions.

ALTER also supports other ideas I mentioned here:
https://www.postgresql.org/message-id/20200706145947.GX4107%40telsasoft.com

- ALTER .. SET interval (for dynamic/deferred RANGE partitioning)
- ALTER .. SET modulus, for HASH partitioning, in the initial implementation,
this would allow CREATING paritions, but wouldn't attempt to handle moving
data if overlapping table already exists:
- Could also set the table-name, maybe by format string;
- Could set "retention interval" for range partitioning;
- Could set if the partitions are themselves partitioned(??)

I think once you allow setting configuration parameters like this, then you
might have an ALTER command to "effect" them, which would create any static
tables required by the configuration. maybe that'd be automatic, but if
there's an "ALTER .. APPLY PARTITIONS" command (or whatever), maybe in the
future, the command could also be used to "repartition" existing table data
into partitions with more fine/course granularity (modulus, or daily vs monthly
range, etc).

--
Justin