st 9. 12. 2020 v 22:59 odesílatel Tom Lane <tgl@sss.pgh.pa.us> napsal:
Here's a couple of little finger exercises to move this along a bit.
0001 adds the ability to attach a subscript handler to an existing data type with ALTER TYPE. This is clearly going to be necessary if we want extension types to be able to use this facility. The only thing that I think might be controversial here is that I did not add the ability to set pg_type.typelem. While that'd be easy enough so far as ALTER TYPE is concerned, I'm not sure that we want to encourage people to change it. The dependency rules mean that the semantics of typelem aren't something you really want to change after-the-fact on an existing type. Also, if we did allow it, any existing SubscriptingRef.refelemtype values in stored views would fail to be updated.
0002 makes use of that to support subscripting of hstore. I'm not sure how much we care about that from a functionality standpoint, but it seems like it might be good to have a contrib module testing that extensions can use this. Also, I thought possibly an example showing what's basically the minimum possible amount of complexity would be good to have. If people like this, I'll finish it up (it lacks docs) and add it.