Re: [HACKERS] Partition-wise join for join between (declaratively)partitioned tables

On 2017/07/20 15:05, Ashutosh Bapat wrote:
> On Wed, Jul 19, 2017 at 9:54 AM, Rafia Sabih
> <rafia.sabih@enterprisedb.com> wrote:
>>
>> Partition information:
>> Type of partitioning - single column range partition
>> Tables partitioned - Lineitem and orders
>>
>> Lineitem -
>> Partition key = l_orderkey
>> No of partitions = 18
>>
>> Orders -
>> Partition key = o_orderkey
>> No of partitions = 11
>>
> 
> The patch set upto 0015 would refuse to join two partitioned relations
> using a partition-wise join if they have different number of
> partitions. Next patches implement a more advanced partition matching
> algorithm only for list partitions. Those next patches would refuse to
> apply partition-wise join for range partitioned tables. So, I am
> confused as to how come partition-wise join is being chosen even when
> the number of partitions differ.

In 21_part_patched.out, I see that lineitem is partitionwise-joined with
itself.
>  Append
  ->  Hash Semi Join      Hash Cond: (l1.l_orderkey = l2.l_orderkey)      Join Filter: (l2.l_suppkey <> l1.l_suppkey)
  Rows Removed by Join Filter: 395116
 
      ->  Parallel Seq Scan on lineitem_001 l1          Filter: (l_receiptdate > l_commitdate)          Rows Removed by
Filter:919654
 
      ->  Hash          Buckets: 8388608  Batches: 1  Memory Usage: 358464kB          ->  Seq Scan on lineitem_001 l2


Thanks,
Amit