Re: Index Searches higher than expected for skip scan

[Peter Geoghegan]

On Fri, Nov 7, 2025 at 6:16 AM Michael Christofides
<mich...@pgmustard.com> wrote:
> Thank you for the incredibly helpful (and fast) replies Peter.

You're welcome.

> Nice idea. Once it sunk in, I realised I could try the explicit "AND 
> boolean_field IN (true, false)" and got it down to 2 index searches:
>
> EXPLAIN (ANALYZE, BUFFERS, VERBOSE, SETTINGS)
> SELECT boolean_field FROM example WHERE integer_field = 5432 AND 
> boolean_field IN (true, false);

That's using the Postgres 17 work. You could also write the query as
"SELECT boolean_field FROM example WHERE integer_field = 5432 AND
boolean_field BETWEEN false AND true" and get 2 index searches. That
variant uses what I've called "range skip scan", which is new in
Postgres 18.

-- 
Peter Geoghegan