Support PostgreSQL-specific aggregate functions (7.0)

[schmitch]

Hello, I'm not sure if it is possible, but it would be great if Npgsql would support more Aggregate Functions, especially when using Group By queries.

Currently only a few of the list at: https://www.postgresql.org/docs/current/functions-aggregate.html are support.
However it would be good if others like bool_and or bool_or will be supported.

I'm not sure if it is even possible since I didn't see custom pgsql only aggregate functions (yet), also it might be troublesome to work with IGrouping<anon type, anon type>.

Work:

• Sync EF Core and implement custom aggregate infrastructure #2393
• Basic PostgreSQL custom aggregate translations #2395
• Support for statistical aggregate functions #532
• Translate basic aggregate spatial functions #2384
• Implement sum and avg PG interval #2339
• Support range aggregate functions over NodaTime Interval and DateInterval #2481

[roji]

We haven't yet looked into supporting PostgreSQL-specific aggregate functions - hopefully the EF Core infrastructure makes that possible. Let's examine this for 3.0.

[austindrenski]

Definitely interested in these along with #532. I believe it's currently feasible, but was nontrivial when I scoped it a few months ago.

[roji]

ST_AsMVT is a PostGIS aggregate function requested here: #457 (comment)

[roji]

Issue tracking the necessary EF Core infrastructure changes: dotnet/efcore#22957

[roji]

Infrastructure for custom aggregates implemented in #2393; this is the counterpart to dotnet/efcore#28092 on the EF Core side.