Hi,
On Fri, Nov 1, 2024 at 2:39 PM jian he <jian.universal...@gmail.com> wrote:
> On Thu, Oct 31, 2024 at 9:09 PM Amit Langote <amitlangot...@gmail.com> wrote:
> >
> >
> > I think we should insist that the join key collation and the partition
> > collation are exactly the same and refuse to match them if they are
> > not.
> >
> > + {
> > + Oid colloid = exprCollation((Node *) expr);
> > +
> > + if ((partcoll != colloid) &&
> > + OidIsValid(colloid) &&
> > + !get_collation_isdeterministic(colloid))
> > + *coll_incompatiable = true;
> >
> > I am not quite sure what is the point of checking whether or not the
> > expression collation is deterministic after confirming that it's not
> > the same as partcoll.
> >
> > Attached 0002 is what I came up with. One thing that's different from
> > what Jian proposed is that match_expr_to_partition_keys() returns -1
> > (expr not matched to any key) when the collation is also not matched
> > instead of using a separate output parameter for that.
> >
> i was thinking that
> CREATE TABLE part_tab (c text collate "POSIX") PARTITION BY LIST(c collate
> "C");
> maybe can do partitionwise join.
> join key collation and the partition key collation same sure would
> make things easy.I think that's maybe ok to do as a new feature (use partitionwise join even if collations differ but are both deterministic?), but we should take a more restrictive approach in a bug fix that is to be back-patched. > about 0002. > Similar to PartCollMatchesExprColl in match_clause_to_partition_key > I think we can simply do the following: > no need to hack match_expr_to_partition_keys. > > @@ -2181,6 +2181,9 @@ have_partkey_equi_join(PlannerInfo *root, > RelOptInfo *joinrel, > if (ipk1 != ipk2) > continue; > > + if (rel1->part_scheme->partcollation[ipk1] != > opexpr->inputcollid) > + return false; Yes, looks like that should be enough, thanks. I've updated the patch. I've added another test case to test the new collation matching code in the code block of have_partkey_equi_join() that pairs partition keys via equivalence class. Adding Ashutosh to cc, as the original author of this code, to get his thoughts on these fixes. -- Thanks, Amit Langote
v4-0002-Disallow-partitionwise-join-when-collation-doesn-.patch
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v4-0001-Disallow-partitionwise-grouping-when-collation-do.patch
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