Re: Partitioned tables and relfilenode

On Fri, Feb 10, 2017 at 03:19:47PM +0900, Amit Langote wrote:
> The new partitioned tables do not contain any data by themselves. Any
> data inserted into a partitioned table is routed to and stored in one of
> its partitions. In fact, it is impossible to insert *any* data before a
> partition (to be precise, a leaf partition) is created. It seems wasteful
> then to allocate physical storage (files) for partitioned tables. If we
> do not allocate the storage, then we must make sure that the right thing
> happens when a command that is intended to manipulate a table's storage
> encounters a partitioned table, the "right thing" here being that the
> command's code either throws an error or warning (in some cases) if the
> specified table is a partitioned table or ignores any partitioned tables
> when it reads the list of relations to process from pg_class. Commands
> that need to be taught about this are vacuum, analyze, truncate, and alter
> table. Specifically:
>
> - In case of vacuum, specifying a partitioned table causes a warning
>
> - In case of analyze, we do not throw an error or warning but simply
> avoid calling do_analyze_rel() *non-recursively*. Further in
> acquire_inherited_sample_rows(), any partitioned tables in the list
> returned by find_all_inheritors() are skipped.
>
> - In case of truncate, only the part which manipulates table's physical
> storage is skipped for partitioned tables.
>
> - ATRewriteTables() skips on the AlteredTableInfo entries for partitioned
> tables, because there is nothing to be done.
>
> - Since we cannot create indexes on partitioned tables anyway, there is
> no need to handle cluster and reindex (they throw a meaningful error
> already due to the lack of indexes.)

I don't think we are doing this, but if the parent table doesn't have a
physical file pg_upgrade will need to be taught that. We have that case
now for unlogged tables on standby servers that we need to address.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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