Re: queryId constant squashing does not support prepared statements

> On Fri, May 09, 2025 at 08:47:58AM GMT, Michael Paquier wrote:
> SELECT query, calls FROM pg_stat_statements ORDER BY query COLLATE "C";
> - query | calls
> -----------------------------------------------------+-------
> - SELECT ARRAY[$1 /*, ... */] | 1
> - SELECT pg_stat_statements_reset() IS NOT NULL AS t | 1
> + query | calls
> +-------------------------------------------------------+-------
> + SELECT ARRAY[$1, $2, $3, $4, $5, $6, $7, $8, $9, $10] | 1
> + SELECT pg_stat_statements_reset() IS NOT NULL AS t | 1
> (2 rows)
>
> Yes, we are going to need more than that for such cases if we want to
> cover all the ground we're aiming for.
>
> Putting that aside, the test coverage for ARRAY[] elements is also
> very limited on HEAD with one single test only with a set of
> constants. We really should improve that, tracking more patterns and
> more mixed combinations to see what gets squashed and what is not. So
> this should be extended with more cases, including expressions,
> parameters and sublinks, with checks on pg_stat_statements.calls to
> see how the counters are aggregated. That's going to be important
> when people play with this code to track how things change when
> manipulating the element jumbling. I'd suggest to do that separately
> of the rest.

Agree, I'll try to extend number of test cases here as a separate patch.