Re: PG 12 draft release notes

Bruce Momjian <bruce(at)momjian(dot)us> writes:
> On Mon, May 20, 2019 at 08:48:15PM -0400, Tom Lane wrote:
>> Yes, this should be in "source code". I think it should be merged
>> with a391ff3c and 74dfe58a into something like
>>
>> Allow extensions to create planner support functions that
>> can provide function-specific selectivity, cost, and
>> row-count estimates that can depend on the function arguments.
>> Support functions can also transform WHERE clauses involving
>> an extension's functions and operators into indexable clauses
>> in ways that the core code cannot for lack of detailed semantic
>> knowledge of those functions/operators.

> The new text is:

> Add support function capability to improve optimizer estimates
> for functions (Tom Lane)

> This allows extensions to create planner support functions that
> can provide function-specific selectivity, cost, and row-count
> estimates that can depend on the function arguments. Also, improve
> in-core estimates for <function>generate_series()</function>,
> <function>unnest()</function>, and functions that return boolean
> values.

Uh ... you completely lost the business about custom indexable clauses.
I agree with Andres that that's the most important aspect of this.

> Notice that there are some improvments in in-core functions. Should this
> still be moved to the source code section?

I doubt that that's worth mentioning at all. It certainly isn't a
reason not to move this to the source-code section, because that's
where we generally put things that are of interest for improving
extensions, which is what this mainly is.

regards, tom lane