Re: Trying to understand why a query is filtering when there is a composite index

Performance is pretty good anyway, and I'm only running 5 r7.large readers
on this service, I was just looking at the query planner and it surprised
me.

On Sun, 18 Aug 2024 at 21:08, Peter Geoghegan <pg(at)bowt(dot)ie> wrote:

> On Sun, Aug 18, 2024 at 10:01 PM Stephen Samuel (Sam) <sam(at)sksamuel(dot)com>
> wrote:
> > Oh as simple as upgrading!
> > Ok great, appreciate the quick reply. Will have to wait for AWS to
> support 17 :)
>
> It is possible to use index quals for both a and b on earlier
> versions, with certain restrictions. You might try setting
> random_page_cost to a much lower value, to see if that allows the
> planner to use such a plan with your real query.
>
> In my experience it's very unlikely that the planner will do that,
> though, even when coaxed. At least when there are this many IN()
> constants. So you probably really will need to upgrade to 17.
>
> --
> Peter Geoghegan
>