Horton

Re: Declarative partitioning - another take

Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>

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From: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2016-08-17T05:33:36Z
Lists: pgsql-hackers 
> +relid_is_partition(Oid relid)
> +{
> +       return SearchSysCacheExists1(PARTRELID, ObjectIdGetDatum(relid));
> +}
>
> This is used in a lot of places, and the overhead of checking it in
> all of those places is not necessarily nil.  Syscache lookups aren't
> free.  What if we didn't create a new catalog for this and instead
> just added a relpartitionbound attribute to pg_class?  It seems a bit
> silly to have a whole extra catalog to store one extra column...
>
>
>

It looks like in most of the places where this function is called it's
using relid_is_partition(RelationGetRelid(rel)). Instead probably we should
check existence of rd_partdesc or rd_partkey within Relation() and make
sure that those members are always set for a partitioned table. That will
avoid cache lookup and may give better performance.

That brings up another question. Can we have rd_partdesc non null and
rd_partkey null or vice-versa. If not, should we club those into a single
structure like Partition (similar to Relation)?



-- 
Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company

Commits

  1. Fix typo.

  2. Document trigger-firing behavior for inheritance/partitioning.

  3. Fire per-statement triggers on partitioned tables.

  4. Set ecxt_scantuple correctly for tuple routing.

  5. Fix interaction of partitioned tables with BulkInsertState.

  6. Avoid core dump for empty prepared statement in an aborted transaction.

  7. Fix some problems in check_new_partition_bound().

  8. Remove unnecessary arguments from partitioning functions.

  9. Fix reporting of constraint violations for table partitioning.

  10. Fix tuple routing in cases where tuple descriptors don't match.

  11. Invalid parent's relcache after CREATE TABLE .. PARTITION OF.

  12. Doc: improve documentation about inheritance.