On Fri, Aug 18, 2017 at 10:12 AM, Amit Langote
<langote_amit...@lab.ntt.co.jp> wrote
>>> 0002: Teach expand_inherited_rtentry to use partition bound order
>> 0004 in [1] expands a multi-level partition hierarchy into similar
>> inheritance hierarchy. That patch doesn't need all OIDs in one go. It
>> will have to handle the partition hierarchy level by level, so most of
>> the code added by this patch will need to be changed by that patch. Is
>> there a way we can somehow change this patch so that the delta in 0004
>> is reduced? That may need rethinking about using
>> RelationGetPartitionDispatchInfo().
> Regarding that, I have a question:
> Does the multi-level partition-wise join planning logic depend on the
> inheritance itself to be expanded in a multi-level aware manner.  That is,
> expanding the partitioned table inheritance in multi-level aware manner in
> expan_inherited_rtentry()?

Yes, it needs AppendRelInfos to retain the parent-child relationship.
Please refer [1], [2], [3] for details.

> Wouldn't it suffice to just have the resulting Append paths be nested per
> multi-level partitioning hierarchy?

We are joining RelOptInfos, so those need to be nested. For those to
be nested, we need AppendRelInfos to preserve parent-child
relationship. Nesting paths doesn't help. Append paths actually should
be flattened out to avoid any extra time consumed in nested Append


Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company

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