Horton

Re: [HACKERS] Runtime Partition Pruning

Dilip Kumar <dilipbalaut@gmail.com>

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From: Dilip Kumar <dilipbalaut@gmail.com>
To: David Rowley <david.rowley@2ndquadrant.com>
Cc: Beena Emerson <memissemerson@gmail.com>, amul sul <sulamul@gmail.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2017-11-16T09:08:16Z
Lists: pgsql-hackers 
On Wed, Nov 15, 2017 at 4:43 AM, David Rowley
<david.rowley@2ndquadrant.com> wrote:
> On 15 November 2017 at 01:57, David Rowley <david.rowley@2ndquadrant.com> wrote:
>> I think to do this you're going to have to store some sort of array
>> that maps the partition index to the subpath in the Append node so you
>> can correctly identify the subpath based on what you're getting back
>> from get_partitions_for_keys(). Perhaps what you had worked previously
>> when we were not returning a Bitmapset with that function.
>>
>> Once you've got that design worked out I can take another look at this.
>

> So some sort of hierarchical structure of the partition hierarchy
> would need to be stored in the Append node and then you'd need to
> search at each level, and then somehow match the results up to the
> subpaths that you have in the Append. Although, I'm still not sure
> this is the best way to go about this.
>

Instead of hierarchical structure can’t we maintain an array (one
entry per partition), and whenever any leaf partition’s subpath
is added to the append rel (in function set_append_rel_pathlist) we
can set that subpath number in corresponding array index.

And, later we can add some wrapper over get_partitions_for_key such
that it can recursively traverse the non-leaf partitions (something
like get_partition_for_tuple does as Amit mentioned.). And, ultimately
gives the output as a list of leaf partition's indexes. Then we can
find the sub-plan number by looking into the array.

-- 
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com

Commits

  1. Initialize ExprStates once in run-time partition pruning

  2. Add bms_prev_member function

  3. Support partition pruning at execution time

  4. Document partprune.c a little better

  5. Fix crash in pg_replication_slot_advance

  6. Add parallel-aware hash joins.

  7. Fix typo.

  8. Allow --with-bonjour to work with non-macOS implementations of Bonjour.

  9. Mention need for --no-inc-recursive in rsync command