Custom aggregation functions

[imatveev]

Currently, there is a way to create custom functions through registerFunction. Together with that - when I try to create a custom function in aggregated queries it throws 🔨 Not supported 🔨 : aggregation function.
Is there a way to define new aggregation functions by yourself?

[oguimbal]

Not yet, no.

I have started a refactoring that might lead to making this possible, though.

[oguimbal]

Of course not :)

Here is some inspiration

That said, you will understand pretty soon that the current pg-mem implementation does not support controling the order of aggregation via array_agg(xxx order by yyy). That was not an issue for the aggregations I implemented so far, but it will for arrag_agg ☹
... that is the point of the incoming refactoring, though

[imatveev]

@oguimbal During my tests I noticed that ordering is not supported not only inside aggregated functions but in aggregated queries at all. Something like this:

    it('supports ordering with aggregated queries', () => {
        expect(many(`create table example(a int, b int);
                    insert into example values (1, 1), (1, 1), (3, 3), (3, 3), (2, 2), (2, 2);
                    select a, max(b) as b from example group by a order by a ASC`))
            .to.deep.equal([{ a: 1, b: 1 }, { a: 2, b: 2 }, { a: 3, b: 3 }]);
    });
 // Throws an error, the returned order is [{ a: 1, b: 1 }, { a: 3, b: 3 }, { a: 2, b: 2 }]

Is it what you meant also, or this is a separate issue?

[oguimbal]

Yes, the current execution engine is a bit broken when it comes to aggregations & nested queries.

Working on it :) Thanks for your unit test, I'm adding it to the suite !

[BasitAli]

It's been a long time since this was last discussed, but do we have a way now to add custom aggregation functions?

[Thiamath]

Hey! Just sneaky nudging this topic!
I found a small problem when using array_agg in a view in my schema. It was supposed to aggregate uuid types and so return uuid[] but it seems to be returning integer[].
Any ideas?