Re: Partial index on JSON column

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