Hi Amit-san From: Amit Langote <amitlangot...@gmail.com> Sent: Tuesday, May 25, 2021 10:06 PM > Hou-san, > > Thanks for the patch and It looks more compact than mine. > > > > After taking a quick look at the patch, I found a possible issue. > > Currently, the patch does not search the parent's partition key expression > recursively. > > For example, If we have multi-level partition: > > Table A is partition of Table B, Table B is partition of Table C. > > It looks like if insert into Table A , then we did not replace the key > > expression > which come from Table C. > > Good catch! Although, I was relieved to realize that it's not *wrong* per > se, as > in it does not produce an incorrect result, but only > *slower* than if the patch was careful enough to replace all the parents' key > expressions. > > > If we want to get the Table C, we might need to use pg_inherit, but it costs > too much to me. > > Instead, maybe we can use the existing logic which already scanned the > > pg_inherit in function generate_partition_qual(). Although this change > > is out of ExecPartitionCheck(). I think we'd better replace all the > > parents and grandparent...'s key expression. Attaching a demo patch based > on the patch you posted earlier. I hope it will help. > > Thanks. > > Though again, I think we can do this without changing the relcache interface, > such as RelationGetPartitionQual(). > > PartitionTupleRouting has all the information that's needed here. > Each partitioned table involved in routing a tuple to the leaf partition has a > PartitionDispatch struct assigned to it. That struct contains the > PartitionKey > and we can access partexprs from there. We can arrange to assemble them > into a single list that is saved to a given partition's ResultRelInfo, that > is, after > converting the expressions to have partition attribute numbers. I tried that > in > the attached updated patch; see the 0002-* patch.
Thanks for the explanation ! Yeah, we can get all the parent table info from PartitionTupleRouting when INSERT into a partitioned table. But I have two issues about using the information from PartitionTupleRouting to get the parent table's key expression: 1) It seems we do not initialize the PartitionTupleRouting when directly INSERT into a partition(not a partitioned table). I think it will be better we let the pre-compute-key_expression feature to be used in all the possible cases, because it could bring nice performance improvement. 2) When INSERT into a partitioned table which is also a partition, the PartitionTupleRouting is initialized after the ExecPartitionCheck. For example: create unlogged table parttable1 (a int, b int, c int, d int) partition by range (partition_func(a)); create unlogged table parttable1_a partition of parttable1 for values from (0) to (5000); create unlogged table parttable1_b partition of parttable1 for values from (5000) to (10000); create unlogged table parttable2 (a int, b int, c int, d int) partition by range (partition_func1(b)); create unlogged table parttable2_a partition of parttable2 for values from (0) to (5000); create unlogged table parttable2_b partition of parttable2 for values from (5000) to (10000); ---When INSERT into parttable2, the code do partitioncheck before initialize the PartitionTupleRouting. insert into parttable2 select 10001,100,10001,100; Best regards, houzj
