CSHARP-5529: Optimize grouping.First().X to not retrieve the entire $$ROOT #1653
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I was wondering if that would be the case. Updating now. |
| @@ -19,6 +19,9 @@ namespace MongoDB.Driver.Linq.Linq3Implementation.Ast.Expressions | |||
| { | |||
| internal static class AstExpressionExtensions | |||
| { | |||
| public static bool IsConstant(this AstExpression expression, BsonValue value) | |||
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Should we rename it to IsConstantEqualsTo or make it return the constant's value instead:
public static bool IsConstant(this AstExpression expression, out BsonValue value)
| @@ -484,9 +484,9 @@ public void GroupBy_where_select_anonymous_type_with_duplicate_accumulators_meth | |||
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| Assert(query, | |||
| 1, | |||
| "{ $group: { _id: '$A', __agg0: { $first: '$$ROOT'} } }", | |||
| "{ $group: { _id: '$A', __agg0: { $first: '$$ROOT'}, __agg1 : { $first : '$B' } } }", | |||
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You could argue that __agg1 is redundant because we've already fetched the entire first $$ROOT so we could compute { $first : "$B" } by calling __agg0.B client-side.
Not sure how easy this would be. Do you think it is worth working on?
| @@ -511,9 +511,9 @@ where g.First().B == "Balloon" | |||
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| Assert(query, | |||
| 1, | |||
| "{ $group: { _id: '$A', __agg0: { $first: '$$ROOT'} } }", | |||
| "{ $group: { _id: '$A', __agg0: { $first: '$$ROOT' }, __agg1 : { $first : '$B' } } }", | |||
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Same comment as above about __agg1.
| "{ $match: { '__agg0.B' : 'Balloon' } }", | ||
| "{ $project: { Key: '$_id', FirstB: '$__agg0.B', _id: 0 } }"); | ||
| "{ $project: { Key: '$_id', FirstB: '$__agg1', _id: 0 } }"); |
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Same comment as above about __agg1.
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I've rebased on See the comments for a question about whether some further work is called for. |
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