Re: Partial index on JSON column

Thanks for the quick reply Tom,

I will try your advice.

The reason why I used ::integer for the INDEX is because I assumed it would
be more efficient both in space and performance.

In the JSONB field, it is actually an integer, i.e. {"location_age": 1,
"suggestion_id": 26}

So, now that I think about it, maybe the way I'm using ::text is wrong.

Any further advice is most appreciated.

Kind regards,
Samuel

On Wed, 20 Feb 2019 at 10:14, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Samuel Williams <space(dot)ship(dot)traveller(at)gmail(dot)com> writes:
> > When I do this query:
>
> > EXPLAIN SELECT COUNT(*) FROM "user_event" WHERE ((parameters ->>
> > 'suggestion_id'::text)::integer = 26) AND what =
> 'suggestion_notification';
>
> > It's slow. I need to explicitly add the NULL constraint:
>
> Try it like
>
> EXPLAIN SELECT COUNT(*) FROM "user_event" WHERE ((parameters ->>
> 'suggestion_id'::text) = '26') AND what = 'suggestion_notification';
>
> I don't think we assume that CoerceViaIO is strict, and without that
> the deduction that the value couldn't be null doesn't hold. In any
> case you're better off without the runtime type conversion: that
> isn't doing much for you except raising the odds of getting an error.
>
> regards, tom lane
>