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Optimize multiple consecutive LIMITs (#35384)
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Fixes #35383
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@ranma42
ranma42 authored Dec 24, 2024
1 parent f163289 commit 02d37a2
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Showing 21 changed files with 221 additions and 162 deletions.
48 changes: 43 additions & 5 deletions src/EFCore.Relational/Query/RelationalQueryableMethodTranslatingExpressionVisitor.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -654,7 +654,7 @@ protected override ShapedQueryExpression TranslateDistinct(ShapedQueryExpression
}

selectExpression.ApplyOffset(translation);
selectExpression.ApplyLimit(TranslateExpression(Expression.Constant(1))!);
ApplyLimit(selectExpression, TranslateExpression(Expression.Constant(1))!);

return source;
}
Expand Down Expand Up @@ -693,7 +693,7 @@ protected override ShapedQueryExpression TranslateExcept(ShapedQueryExpression s
_queryCompilationContext.Logger.FirstWithoutOrderByAndFilterWarning();
}

selectExpression.ApplyLimit(TranslateExpression(Expression.Constant(1))!);
ApplyLimit(selectExpression, TranslateExpression(Expression.Constant(1))!);

return source.ShaperExpression.Type != returnType
? source.UpdateShaperExpression(Expression.Convert(source.ShaperExpression, returnType))
Expand Down Expand Up @@ -940,7 +940,7 @@ private SqlExpression CreateJoinPredicate(Expression outerKey, Expression innerK
}

selectExpression.ReverseOrderings();
selectExpression.ApplyLimit(TranslateExpression(Expression.Constant(1))!);
ApplyLimit(selectExpression, TranslateExpression(Expression.Constant(1))!);

return source.ShaperExpression.Type != returnType
? source.UpdateShaperExpression(Expression.Convert(source.ShaperExpression, returnType))
Expand Down Expand Up @@ -1208,7 +1208,7 @@ protected override Expression VisitMethodCall(MethodCallExpression methodCallExp
}

var selectExpression = (SelectExpression)source.QueryExpression;
selectExpression.ApplyLimit(TranslateExpression(Expression.Constant(_subquery ? 1 : 2))!);
ApplyLimit(selectExpression, TranslateExpression(Expression.Constant(_subquery ? 1 : 2))!);

return source.ShaperExpression.Type != returnType
? source.UpdateShaperExpression(Expression.Convert(source.ShaperExpression, returnType))
Expand Down Expand Up @@ -1258,11 +1258,49 @@ protected override Expression VisitMethodCall(MethodCallExpression methodCallExp
_queryCompilationContext.Logger.RowLimitingOperationWithoutOrderByWarning();
}

selectExpression.ApplyLimit(translation);
ApplyLimit(selectExpression, translation);

return source;
}

private void ApplyLimit(SelectExpression selectExpression, SqlExpression limit)
{
var oldLimit = selectExpression.Limit;

if (oldLimit is null)
{
selectExpression.SetLimit(limit);
return;
}

if (oldLimit is SqlConstantExpression { Value: int oldConst } && limit is SqlConstantExpression { Value: int newConst })
{
// if both the old and new limit are constants, use the smaller one
// (aka constant-fold LEAST(constA, constB))
if (oldConst > newConst)
{
selectExpression.SetLimit(limit);
}

return;
}

if (oldLimit.Equals(limit))
{
return;
}

// if possible, use LEAST(oldLimit, limit); otherwise, use nested queries
if (_sqlTranslator.GenerateLeast([oldLimit, limit], limit.Type) is { } newLimit)
{
selectExpression.SetLimit(newLimit);
}
else
{
selectExpression.ApplyLimit(limit);
}
}

/// <inheritdoc />
protected override ShapedQueryExpression? TranslateTakeWhile(ShapedQueryExpression source, LambdaExpression predicate)
=> null;
Expand Down
10 changes: 10 additions & 0 deletions src/EFCore.Relational/Query/SqlExpressions/SelectExpression.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -1924,6 +1924,16 @@ public void ApplyLimit(SqlExpression sqlExpression)
PushdownIntoSubquery();
}

SetLimit(sqlExpression);
}

/// <summary>
/// Sets a new limit of the <see cref="SelectExpression" /> to limit the number of rows returned in the result set.
/// </summary>
/// <param name="sqlExpression">An expression representing limit row count.</param>
[EntityFrameworkInternal]
public void SetLimit(SqlExpression sqlExpression)
{
Limit = sqlExpression;

if (Offset is null && Limit is SqlConstantExpression { Value: 1 })
Expand Down
16 changes: 16 additions & 0 deletions test/EFCore.Cosmos.FunctionalTests/Query/NorthwindSelectQueryCosmosTest.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -1096,6 +1096,22 @@ public override async Task SelectMany_correlated_with_outer_7(bool async)
AssertSql();
}

public override async Task SelectMany_with_multiple_Take(bool async)
{
// Cosmos client evaluation. Issue #17246.
await AssertTranslationFailed(() => base.SelectMany_with_multiple_Take(async));

AssertSql();
}

public override async Task Select_with_multiple_Take(bool async)
{
// Cosmos client evaluation. Issue #17246.
await AssertTranslationFailed(() => base.Select_with_multiple_Take(async));

AssertSql();
}

public override async Task FirstOrDefault_over_empty_collection_of_value_type_returns_correct_results(bool async)
{
// Cosmos client evaluation. Issue #17246.
Expand Down
14 changes: 14 additions & 0 deletions test/EFCore.Specification.Tests/Query/NorthwindSelectQueryTestBase.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -1441,6 +1441,20 @@ from o in ss.Set<Order>().Where(o => c.CustomerID.Length >= o.CustomerID.Length)
AssertEqual(e.o, a.o);
});

[ConditionalTheory]
[MemberData(nameof(IsAsyncData))]
public virtual Task SelectMany_with_multiple_Take(bool async)
=> AssertQuery(
async,
ss => ss.Set<Customer>().SelectMany(c => c.Orders.OrderBy(o => o.OrderID).Take(5).Take(3)));

[ConditionalTheory]
[MemberData(nameof(IsAsyncData))]
public virtual Task Select_with_multiple_Take(bool async)
=> AssertQuery(
async,
ss => ss.Set<Customer>().OrderBy(o => o.CustomerID).Take(5).Take(3));

[ConditionalTheory]
[MemberData(nameof(IsAsyncData))]
public virtual Task FirstOrDefault_over_empty_collection_of_value_type_returns_correct_results(bool async)
Expand Down
12 changes: 5 additions & 7 deletions test/EFCore.SqlServer.FunctionalTests/Query/ManyToManyNoTrackingQuerySqlServerTest.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -300,17 +300,15 @@ public override async Task Skip_navigation_order_by_single_or_default(bool async
"""
SELECT [s0].[Id], [s0].[Name]
FROM [EntityOnes] AS [e]
OUTER APPLY (
SELECT TOP(1) [s].[Id], [s].[Name]
LEFT JOIN (
SELECT [s].[Id], [s].[Name], [s].[LeftId]
FROM (
SELECT TOP(1) [e0].[Id], [e0].[Name]
SELECT [e0].[Id], [e0].[Name], [j].[LeftId], ROW_NUMBER() OVER(PARTITION BY [j].[LeftId] ORDER BY [e0].[Id]) AS [row]
FROM [JoinOneSelfPayload] AS [j]
INNER JOIN [EntityOnes] AS [e0] ON [j].[RightId] = [e0].[Id]
WHERE [e].[Id] = [j].[LeftId]
ORDER BY [e0].[Id]
) AS [s]
ORDER BY [s].[Id]
) AS [s0]
WHERE [s].[row] <= 1
) AS [s0] ON [e].[Id] = [s0].[LeftId]
""");
}

Expand Down
12 changes: 5 additions & 7 deletions test/EFCore.SqlServer.FunctionalTests/Query/ManyToManyQuerySqlServerTest.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -299,17 +299,15 @@ public override async Task Skip_navigation_order_by_single_or_default(bool async
"""
SELECT [s0].[Id], [s0].[Name]
FROM [EntityOnes] AS [e]
OUTER APPLY (
SELECT TOP(1) [s].[Id], [s].[Name]
LEFT JOIN (
SELECT [s].[Id], [s].[Name], [s].[LeftId]
FROM (
SELECT TOP(1) [e0].[Id], [e0].[Name]
SELECT [e0].[Id], [e0].[Name], [j].[LeftId], ROW_NUMBER() OVER(PARTITION BY [j].[LeftId] ORDER BY [e0].[Id]) AS [row]
FROM [JoinOneSelfPayload] AS [j]
INNER JOIN [EntityOnes] AS [e0] ON [j].[RightId] = [e0].[Id]
WHERE [e].[Id] = [j].[LeftId]
ORDER BY [e0].[Id]
) AS [s]
ORDER BY [s].[Id]
) AS [s0]
WHERE [s].[row] <= 1
) AS [s0] ON [e].[Id] = [s0].[LeftId]
""");
}

Expand Down
124 changes: 68 additions & 56 deletions test/EFCore.SqlServer.FunctionalTests/Query/NorthwindSelectQuerySqlServerTest.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -760,14 +760,10 @@ public override async Task Project_single_element_from_collection_with_OrderBy_T
AssertSql(
"""
SELECT (
SELECT TOP(1) [o0].[CustomerID]
FROM (
SELECT TOP(1) [o].[CustomerID], [o].[OrderID]
FROM [Orders] AS [o]
WHERE [c].[CustomerID] = [o].[CustomerID]
ORDER BY [o].[OrderID]
) AS [o0]
ORDER BY [o0].[OrderID])
SELECT TOP(1) [o].[CustomerID]
FROM [Orders] AS [o]
WHERE [c].[CustomerID] = [o].[CustomerID]
ORDER BY [o].[OrderID])
FROM [Customers] AS [c]
""");
}
Expand Down Expand Up @@ -828,14 +824,10 @@ public override async Task Project_single_element_from_collection_with_OrderBy_T
AssertSql(
"""
SELECT (
SELECT TOP(1) [o0].[CustomerID]
FROM (
SELECT TOP(1) [o].[CustomerID], [o].[OrderID]
FROM [Orders] AS [o]
WHERE [c].[CustomerID] = [o].[CustomerID]
ORDER BY [o].[OrderID]
) AS [o0]
ORDER BY [o0].[OrderID])
SELECT TOP(1) [o].[CustomerID]
FROM [Orders] AS [o]
WHERE [c].[CustomerID] = [o].[CustomerID]
ORDER BY [o].[OrderID])
FROM [Customers] AS [c]
WHERE [c].[CustomerID] = N'ALFKI'
""");
Expand Down Expand Up @@ -869,14 +861,10 @@ public override async Task Project_single_element_from_collection_with_multiple_
AssertSql(
"""
SELECT (
SELECT TOP(1) [o0].[CustomerID]
FROM (
SELECT TOP(2) [o].[CustomerID], [o].[OrderID], [o].[OrderDate]
FROM [Orders] AS [o]
WHERE [c].[CustomerID] = [o].[CustomerID]
ORDER BY [o].[OrderID], [o].[OrderDate] DESC
) AS [o0]
ORDER BY [o0].[OrderID], [o0].[OrderDate] DESC)
SELECT TOP(1) [o].[CustomerID]
FROM [Orders] AS [o]
WHERE [c].[CustomerID] = [o].[CustomerID]
ORDER BY [o].[OrderID], [o].[OrderDate] DESC)
FROM [Customers] AS [c]
""");
}
Expand All @@ -892,14 +880,10 @@ await base
AssertSql(
"""
SELECT (
SELECT TOP(1) [o0].[c]
FROM (
SELECT TOP(2) CAST(LEN([o].[CustomerID]) AS int) AS [c], [o].[OrderID], [o].[OrderDate]
FROM [Orders] AS [o]
WHERE [c].[CustomerID] = [o].[CustomerID]
ORDER BY [o].[OrderID], [o].[OrderDate] DESC
) AS [o0]
ORDER BY [o0].[OrderID], [o0].[OrderDate] DESC)
SELECT TOP(1) CAST(LEN([o].[CustomerID]) AS int)
FROM [Orders] AS [o]
WHERE [c].[CustomerID] = [o].[CustomerID]
ORDER BY [o].[OrderID], [o].[OrderDate] DESC)
FROM [Customers] AS [c]
""");
}
Expand All @@ -911,14 +895,10 @@ public override async Task Project_single_element_from_collection_with_multiple_
AssertSql(
"""
SELECT (
SELECT TOP(1) [o0].[CustomerID]
FROM (
SELECT TOP(2) [o].[CustomerID], [o].[OrderDate]
FROM [Orders] AS [o]
WHERE [c].[CustomerID] = [o].[CustomerID]
ORDER BY [o].[CustomerID], [o].[OrderDate] DESC
) AS [o0]
ORDER BY [o0].[CustomerID], [o0].[OrderDate] DESC)
SELECT TOP(1) [o].[CustomerID]
FROM [Orders] AS [o]
WHERE [c].[CustomerID] = [o].[CustomerID]
ORDER BY [o].[CustomerID], [o].[OrderDate] DESC)
FROM [Customers] AS [c]
""");
}
Expand All @@ -930,15 +910,11 @@ public override async Task Project_single_element_from_collection_with_OrderBy_o
AssertSql(
"""
SELECT COALESCE((
SELECT TOP(1) [s].[OrderID]
FROM (
SELECT TOP(1) [o0].[OrderID], [p].[ProductName]
FROM [Order Details] AS [o0]
INNER JOIN [Products] AS [p] ON [o0].[ProductID] = [p].[ProductID]
WHERE [o].[OrderID] = [o0].[OrderID]
ORDER BY [p].[ProductName]
) AS [s]
ORDER BY [s].[ProductName]), 0)
SELECT TOP(1) [o0].[OrderID]
FROM [Order Details] AS [o0]
INNER JOIN [Products] AS [p] ON [o0].[ProductID] = [p].[ProductID]
WHERE [o].[OrderID] = [o0].[OrderID]
ORDER BY [p].[ProductName]), 0)
FROM [Orders] AS [o]
WHERE [o].[OrderID] < 10300
""");
Expand All @@ -953,17 +929,15 @@ public override async Task Project_single_element_from_collection_with_OrderBy_o
"""
SELECT [s0].[OrderID], [s0].[ProductID], [s0].[Discount], [s0].[Quantity], [s0].[UnitPrice]
FROM [Orders] AS [o]
OUTER APPLY (
SELECT TOP(1) [s].[OrderID], [s].[ProductID], [s].[Discount], [s].[Quantity], [s].[UnitPrice]
LEFT JOIN (
SELECT [s].[OrderID], [s].[ProductID], [s].[Discount], [s].[Quantity], [s].[UnitPrice]
FROM (
SELECT TOP(1) [o0].[OrderID], [o0].[ProductID], [o0].[Discount], [o0].[Quantity], [o0].[UnitPrice], [p].[ProductName]
SELECT [o0].[OrderID], [o0].[ProductID], [o0].[Discount], [o0].[Quantity], [o0].[UnitPrice], ROW_NUMBER() OVER(PARTITION BY [o0].[OrderID] ORDER BY [p].[ProductName]) AS [row]
FROM [Order Details] AS [o0]
INNER JOIN [Products] AS [p] ON [o0].[ProductID] = [p].[ProductID]
WHERE [o].[OrderID] = [o0].[OrderID]
ORDER BY [p].[ProductName]
) AS [s]
ORDER BY [s].[ProductName]
) AS [s0]
WHERE [s].[row] <= 1
) AS [s0] ON [o].[OrderID] = [s0].[OrderID]
WHERE [o].[OrderID] < 10250
""");
}
Expand Down Expand Up @@ -1336,6 +1310,44 @@ WHERE CAST(LEN([c].[CustomerID]) AS int) >= CAST(LEN([o].[CustomerID]) AS int)
""");
}

public override async Task SelectMany_with_multiple_Take(bool async)
{
await base.SelectMany_with_multiple_Take(async);

AssertSql(
"""
SELECT [o1].[OrderID], [o1].[CustomerID], [o1].[EmployeeID], [o1].[OrderDate]
FROM [Customers] AS [c]
INNER JOIN (
SELECT [o0].[OrderID], [o0].[CustomerID], [o0].[EmployeeID], [o0].[OrderDate]
FROM (
SELECT [o].[OrderID], [o].[CustomerID], [o].[EmployeeID], [o].[OrderDate], ROW_NUMBER() OVER(PARTITION BY [o].[CustomerID] ORDER BY [o].[OrderID]) AS [row]
FROM [Orders] AS [o]
) AS [o0]
WHERE [o0].[row] <= 3
) AS [o1] ON [c].[CustomerID] = [o1].[CustomerID]
""");
}

public override async Task Select_with_multiple_Take(bool async)
{
await base.Select_with_multiple_Take(async);

AssertSql(
"""
@p0='3'
@p='5'
SELECT TOP(@p0) [c0].[CustomerID], [c0].[Address], [c0].[City], [c0].[CompanyName], [c0].[ContactName], [c0].[ContactTitle], [c0].[Country], [c0].[Fax], [c0].[Phone], [c0].[PostalCode], [c0].[Region]
FROM (
SELECT TOP(@p) [c].[CustomerID], [c].[Address], [c].[City], [c].[CompanyName], [c].[ContactName], [c].[ContactTitle], [c].[Country], [c].[Fax], [c].[Phone], [c].[PostalCode], [c].[Region]
FROM [Customers] AS [c]
ORDER BY [c].[CustomerID]
) AS [c0]
ORDER BY [c0].[CustomerID]
""");
}

public override async Task FirstOrDefault_over_empty_collection_of_value_type_returns_correct_results(bool async)
{
await base.FirstOrDefault_over_empty_collection_of_value_type_returns_correct_results(async);
Expand Down
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