Query: in case of joins, we shouldn't be materializing Inner if the qsre itself is not present in final projection

[maumar]

Query:

from g in ctx.Gears
join inner in (
     from g2 in ctx.Gears
     select new { g2.Nickname }
     ) on g.Nickname equals inner.Nickname
select g;

produces the following query plan:

(QueryContext queryContext) => IEnumerable<Gear> _InterceptExceptions(
    source: IEnumerable<Gear> _ShapedQuery(
        queryContext: queryContext, 
        shaperCommandContext: SelectExpression: 
            SELECT [g].[Nickname], [g].[SquadId], [g].[AssignedCityName], [g].[CityOrBirthName], [g].[Discriminator], [g].[FullName], [g].[HasSoulPatch], [g].[LeaderNickname], [g].[LeaderSquadId], [g].[Rank], [t].[Nickname]
            FROM [Gears] AS [g]
            INNER JOIN (
                SELECT [g2].[Nickname]
                FROM [Gears] AS [g2]
                WHERE [g2].[Discriminator] IN (N'Officer', N'Gear')
            ) AS [t] ON [g].[Nickname] = [t].[Nickname]
            WHERE [g].[Discriminator] IN (N'Officer', N'Gear'), 
        shaper: (BufferedOffsetEntityShaper<Gear>
        materializer: (TransparentIdentifier<Gear, <>f__AnonymousType227<string>> t0) => t0.Outer)), 
    contextType: TestModels.GearsOfWarModel.GearsOfWarContext, 
    logger: DiagnosticsLogger<Query>, 
    queryContext: queryContext)

We actually don't need to materialize inner, so the materializer could be simplified by stripping the transparent identifier.

Another case that could also be improved, is when element of the inner is present in the final projection, but the inner qsre is not. In that case, we also don't need to materialize the inner and we can directly bind to the value buffer instead:

from g in ctx.Gears
join inner in (
     from g2 in ctx.Gears
     select new { g2.Nickname }
     ) on g.Nickname equals inner.Nickname
select new { g, inner.Nickname };

[smitpatel]

Also related #9892

[smitpatel]

        [ConditionalFact]
        public virtual void Anonymous_projection_AsNoTracking_Min()
        {
            AssertQueryScalar<Order>(
                os => os.Select(o => new { A = o.CustomerID, B = o.OrderDate })
                    .AsNoTracking() // Just to cause a subquery
                    .Select(e => e.B));
        }

This causes the selector to be evaluated on client. With aggregate operator like Min/Max causes really bad query. Eliminating anonymous types would be helpful in such cases.

[maumar]

verified this issue has been fixed in 3.0