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

On Mon, Mar 13, 2017 at 3:24 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> Haven't looked at 0007 yet.

+ if (rel->part_scheme)
+ {
+ int cnt_parts;
+
+ for (cnt_parts = 0; cnt_parts < nparts; cnt_parts++)
+ {
+ if (rel->part_oids[cnt_parts] ==
childRTE->relid)
+ {
+ Assert(!rel->part_rels[cnt_parts]);
+ rel->part_rels[cnt_parts] = childrel;
+ }
+ }
+ }

It's not very appealing to use an O(n^2) algorithm here. I wonder if
we could arrange things so that inheritance expansion expands
partitions in the right order, and then we could just match them up
one-to-one. This would probably require an alternate version of
find_all_inheritors() that expand_inherited_rtentry() would call only
for partitioned tables. Failing that, another idea would be to use
qsort() or qsort_arg() to put the partitions in the right order.

+ if (relation->rd_rel->relkind != RELKIND_PARTITIONED_TABLE ||
+ !inhparent ||
+ !(rel->part_scheme = find_partition_scheme(root, relation)))

Maybe just don't call this function in the first place in the
!inhparent case, instead of passing down an argument that must always
be true.

+ /* Match the partition key types. */
+ for (cnt_pks = 0; cnt_pks < partnatts; cnt_pks++)
+ {
+ /*
+ * For types, it suffices to match the type
id, mod and collation;
+ * len, byval and align are depedent on the first two.
+ */
+ if (part_key->partopfamily[cnt_pks] !=
part_scheme->partopfamily[cnt_pks] ||
+ part_key->partopcintype[cnt_pks] !=
part_scheme->partopcintype[cnt_pks] ||
+ part_key->parttypid[cnt_pks] !=
part_scheme->key_types[cnt_pks] ||
+ part_key->parttypmod[cnt_pks] !=
part_scheme->key_typmods[cnt_pks] ||
+ part_key->parttypcoll[cnt_pks] !=
part_scheme->key_collations[cnt_pks])
+ break;
+ }

I think memcmp() might be better than a for-loop.

Overall this one looks pretty good and straightforward. Of course, I
haven't looked at the main act (0009) yet.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
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