Document SQLite client evaluation of decimals as a specific breaking change

[ajcvickers]

See dotnet/efcore#15324

[bricelam]

Might also be worth mentioning DateTimeOffset, TimeSpan, and ulong too.

[bricelam]

The operations we should block server-eval for:

Expression	DateTime	DateTimeOffset	decimal	TimeSpan*	ulong
-x			❌	❌	✔
x + y	❌*	❌	❌	❌	✔
x / y			❌	❌	❌
x > y	✔	❌	❌	❌	❌
x >= y	✔	❌	❌	❌	❌
x < y	✔	❌	❌	❌	❌
x <= y	✔	❌	❌	❌	❌
x % y			❌		❌
x * y			❌	❌	❌
x - y	❌*	❌	❌	❌	✔
xs.Average()			❌
xs.Max()		❌	❌	❌	❌
xs.Min()		❌	❌	❌	❌
xs.OrderBy()	✔	❌	❌	❌	❌
xs.Sum()			❌		✔

* We can make TimeSpan work by registering two UDFs. See bricelam/EFCore.SqliteEx#1

[ajcvickers]

@bricelam What does a tick represent as opposed to an x?

Also, would it, theoretically, be possible to make all of these work (or at least all that are non-lossy) by registering functions that understood the mapping and did conversion back to the appropriate .NET type? If so, should we consider doing this automatically at least when using EF Core?

[bricelam]

✔ - Works in SQL
❌ - Doesn't work
(blank) - No such operation

Yes, in theory, we could register UDFs for every operation and translate to them. But this is different from TimeSpan where we only need two UDFs to enable every operation.

Should we consider doing this automatically at least when using EF Core?

I don't like the idea of doing it automatically since our UDF names may collide with the application's. The TimeSpan issue mentions making it an opt-in part of the provider via optionsBuilder.UseSqlite(connection, x => x.UseTimeSpan())

[ajcvickers]

Opt-in seems a good approach.

[bricelam]

Added to docs here: https://docs.microsoft.com/en-us/ef/core/providers/sqlite/limitations#query-limitations
All invalid operations on these types are blocked in v3.
TimeSpan work tracked here: bricelam/EFCore.SqliteEx#1