Re: BUG #18344: Pruning tables partitioned by bool range fails with invalid strategy

On Sat, 17 Feb 2024 at 01:32, David Rowley <dgrowleyml(at)gmail(dot)com> wrote:
> I see three options:
>
> 1) Make get_matching_list_bounds() work for bool IS NOT clauses by
> properly including the NULL partition when handling a bool IS NOT
> clause.
> 2) Just don't generate a pruning step for bool IS NOT clauses.
> 3) Just always include the NULL partition in
> get_matching_list_bounds's "if (opstrategy == InvalidStrategy)" block.

It turns out there's a 4th, and much better option that allows this
just to work without any weirdness.

The method used in partprune.c to handle "partkey IN ('const1',
'const2')" is to transform that into "partkey = 'const1' OR partkey =
'const2'". Whenever we see a ScalarArrayOpExpr with consts, we just
form such an OR clause and recursively generate pruning steps for the
OR clause. That'll end up creating two pruning steps and combining
them with a PARTPRUNE_COMBINE_UNION.

We can do the same for BooleanTests. Given a clause such as: "partkey
IS NOT false", we can just generate the clause "partkey IS true OR
partkey IS NULL" and recursively generate steps for that.

I've attached a draft patch. I'll work on this more after I sleep.

I'm tempted to go a bit further in master only and add support for
bool IS NOT UNKNOWN and bool IS UNKNOWN using the same method.

David