On Wed, 9 Oct 2024 at 20:07, Shayon Mukherjee <shayonj@gmail.com> wrote:
[thinking…] Unless - we try to do support both a GUC and the ALTER INDEX ENABLE/DISABLE grammar + isdisabled attribute on pg_index?
I just wanted to explain my point of view on this. This is my opinion and is by no means authoritative.
I was interested in this patch when you proposed it as an ALTER INDEX option. I know other committers seem interested, but I personally don't have any interest in the GUC option. I think the reason I dislike it is that it's yet another not even half-baked take on planner hints (the other one being enable* GUCs). I often thought that if we ever did planner hints that it would be great to have multiple ways to specify the hints. Ordinarily, I'd expect some special comment type as the primary method to specify hints, but equally, it would be nice to be able to specify them in other ways. e.g. a GUC to have them apply to more than just 1 query. Useful for things such as "don't use index X".
+1. A GUC can be done as a contrib module using existing hooks, and I think that's already been done outside of core, perhaps multiple times. That certainly doesn't mean we CAN'T add it as an in-core feature, but I do think "yet another not even half-baked take on planner hints" is a fair description. What I would personally like to see is for us to ship one or possibly more than one contrib module that let people do hint-like things in useful ways, and this could be a part of that. But I think we need better infrastructure for controlling the planner behavior first, hence the "allowing extensions to control planner behavior" thread.
Thank you for sharing this Robert. I like the idea behind "allowing extensions to control planner behavior” overall and I think it does help towards a powerful extension ecosystem too. I wonder if there is a reality where we can achieve both the outcomes here
- Support disabling of indexes [1] through ALTER command
- While also building on "allowing extensions to control planner behavior” for the reasons above?
