Implement ExecuteDelete

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Synced against dotnet/efcore#28492.

Nothing much to see here yet, the tests are implemented and all pass (see last commit only). The PostgreSQL-specific USING syntax for joining needs to be implemented, will do that following upstream implementation for SQL Server.

Closes #2450

/cc @smitpatel

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@smitpatel note this filter to only accept inner joins over tables (since that's what PG USING does/supports).

[smitpatel]

Little sad that only inner join is supported. I will add test which uses multiple inner joins. What do you think about cross apply?

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Yeah, I agree it's sad... Good to add some more tests (multiple inner joins, left/cross...).

I'll take a look at whether USING allows cross apply (lateral join as PG calls it). My gut says no.

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@smitpatel unfortunately cross apply (lateral join) doesn't work with DELETE's USING:

DELETE FROM "Order Details" AS o
USING (
    SELECT o0."OrderID", o0."CustomerID", o0."EmployeeID", o0."OrderDate"
    FROM "Orders" AS o0
    WHERE o0."OrderID" < o."OrderID"
    ORDER BY o0."OrderID" NULLS FIRST
    LIMIT 100 OFFSET 0
) AS t
WHERE o."OrderID" < 10276

This errors with:

42P01: invalid reference to FROM-clause entry for table "o"

Note that it is apparently possible to do it with UPDATE's FROM, as here:

UPDATE x
SET foo=bar
FROM a, LATERAL (...)

I tried putting LATERAL betwen the subquery and USING in the DELETE above and that didn't work either 😢

[smitpatel]

Does it work in id in subquery form?

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You mean the default behavior with the PK comparison? Sure, here's your test which passes. It's just that DELETE"s USING clause is apparently only for inner joins...

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@smitpatel here's the conversion to the PG-specific delete expression, as discussed in #2449 (comment). I think it does make it nicer, and query SQL generation is now trivial as it should be. Any thoughts?