Work on LEAST/GREATEST, Math.Min/Max

Closes dotnet#27794
Closes dotnet#31681
Closes dotnet#32332

Author: roji

src/EFCore.Relational/Extensions/RelationalDbFunctionsExtensions.cs

@@ -36,4 +36,24 @@ public static TProperty Collate<TProperty>(
         TProperty operand,
         [NotParameterized] string collation)
         => throw new InvalidOperationException(CoreStrings.FunctionOnClient(nameof(Collate)));
+
+    /// <summary>
+    ///     Returns the smallest value from the given list of values. Usually corresponds to the <c>LEAST</c> SQL function.
+    /// </summary>
+    /// <param name="_">The <see cref="DbFunctions" /> instance.</param>
+    /// <param name="values">The list of values from which return the smallest value.</param>
+    public static T Least<T>(
+        this DbFunctions _,
+        [NotParameterized] params T[] values)
+        => throw new InvalidOperationException(CoreStrings.FunctionOnClient(nameof(Least)));
+
+    /// <summary>
+    ///     Returns the greatest value from the given list of values. Usually corresponds to the <c>GREATEST</c> SQL function.
+    /// </summary>
+    /// <param name="_">The <see cref="DbFunctions" /> instance.</param>
+    /// <param name="values">The list of values from which return the greatest value.</param>
+    public static T Greatest<T>(
+        this DbFunctions _,
+        [NotParameterized] params T[] values)
+        => throw new InvalidOperationException(CoreStrings.FunctionOnClient(nameof(Greatest)));
 }

src/EFCore.Relational/Query/ExpressionExtensions.cs

@@ -34,4 +34,23 @@ public static class ExpressionExtensions
 
         return null;
     }
+
+    /// <summary>
+    ///     Infers type mapping from given <see cref="SqlExpression" />s.
+    /// </summary>
+    /// <param name="expressions">Expressions to search for to find the type mapping.</param>
+    /// <returns>A relational type mapping inferred from the expressions.</returns>
+    public static RelationalTypeMapping? InferTypeMapping(IReadOnlyList<SqlExpression> expressions)
+    {
+        for (var i = 0; i < expressions.Count; i++)
+        {
+            var sql = expressions[i];
+            if (sql.TypeMapping != null)
+            {
+                return sql.TypeMapping;
+            }
+        }
+
+        return null;
+    }
 }

src/EFCore.Relational/Query/ISqlExpressionFactory.cs

@@ -483,4 +483,30 @@ SqlFunctionExpression NiladicFunction(
     /// <param name="tableExpressionBase">A table source to project from.</param>
     /// <returns>An expression representing a SELECT in a SQL tree.</returns>
     SelectExpression Select(IEntityType entityType, TableExpressionBase tableExpressionBase);
+
+    /// <summary>
+    ///     Attempts to creates a new expression that returns the smallest value from a list of expressions, e.g. an invocation of the
+    ///     <c>LEAST</c> SQL function.
+    /// </summary>
+    /// <param name="expressions">An entity type to project.</param>
+    /// <param name="resultType">The result CLR type for the returned expression.</param>
+    /// <param name="leastExpression">The expression which computes the smallest value.</param>
+    /// <returns><see langword="true" /> if the expression could be created, <see langword="false" /> otherwise.</returns>
+    bool TryCreateLeast(
+        IReadOnlyList<SqlExpression> expressions,
+        Type resultType,
+        [NotNullWhen(true)] out SqlExpression? leastExpression);
+
+    /// <summary>
+    ///     Attempts to creates a new expression that returns the greatest value from a list of expressions, e.g. an invocation of the
+    ///     <c>GREATEST</c> SQL function.
+    /// </summary>
+    /// <param name="expressions">An entity type to project.</param>
+    /// <param name="resultType">The result CLR type for the returned expression.</param>
+    /// <param name="greatestExpression">The expression which computes the greatest value.</param>
+    /// <returns><see langword="true" /> if the expression could be created, <see langword="false" /> otherwise.</returns>
+    bool TryCreateGreatest(
+        IReadOnlyList<SqlExpression> expressions,
+        Type resultType,
+        [NotNullWhen(true)] out SqlExpression? greatestExpression);
 }

src/EFCore.Relational/Query/RelationalQueryableMethodTranslatingExpressionVisitor.cs

@@ -265,7 +265,6 @@ protected override Expression VisitMethodCall(MethodCallExpression methodCallExp
         if (translated == QueryCompilationContext.NotTranslatedExpression)
         {
             // Attempt to translate access into a primitive collection property (i.e. array column)
-
             if (_sqlTranslator.TryTranslatePropertyAccess(methodCallExpression, out var translatedExpression, out var property)
                 && property is IProperty { IsPrimitiveCollection: true } regularProperty
                 && translatedExpression is SqlExpression sqlExpression)
@@ -570,35 +569,8 @@ protected override ShapedQueryExpression TranslateConcat(ShapedQueryExpression s
         }
 
         // Pattern-match Contains over ValuesExpression, translating to simplified 'item IN (1, 2, 3)' with constant elements
-        if (source.QueryExpression is SelectExpression
-            {
-                Tables:
-                [
-                    ValuesExpression
-                    {
-                        RowValues: [{ Values.Count: 2 }, ..],
-                        ColumnNames: [ValuesOrderingColumnName, ValuesValueColumnName]
-                    } valuesExpression
-                ],
-                Predicate: null,
-                GroupBy: [],
-                Having: null,
-                IsDistinct: false,
-                Limit: null,
-                Offset: null,
-                // Note that in the context of Contains we don't care about orderings
-            }
-            // Make sure that the source projects the column from the ValuesExpression directly, i.e. no projection out with some expression
-            && projection is ColumnExpression projectedColumn
-            && projectedColumn.Table == valuesExpression)
+        if (TryExtractBareInlineCollectionValues(source, out var values))
         {
-            var values = new SqlExpression[valuesExpression.RowValues.Count];
-            for (var i = 0; i < values.Length; i++)
-            {
-                // Skip the first value (_ord), which is irrelevant for Contains
-                values[i] = valuesExpression.RowValues[i].Values[1];
-            }
-
             var inExpression = _sqlExpressionFactory.In(translatedItem, values);
             return source.Update(_sqlExpressionFactory.Select(inExpression), source.ShaperExpression);
         }
@@ -970,13 +942,19 @@ private SqlExpression CreateJoinPredicate(Expression outerKey, Expression innerK
 
     /// <inheritdoc />
     protected override ShapedQueryExpression? TranslateMax(ShapedQueryExpression source, LambdaExpression? selector, Type resultType)
-        => TranslateAggregateWithSelector(
-            source, selector, t => QueryableMethods.MaxWithoutSelector.MakeGenericMethod(t), throwWhenEmpty: true, resultType);
+        => TryExtractBareInlineCollectionValues(source, out var values)
+            && _sqlExpressionFactory.TryCreateGreatest(values, resultType, out var greatestExpression)
+                ? source.Update(_sqlExpressionFactory.Select(greatestExpression), source.ShaperExpression)
+                : TranslateAggregateWithSelector(
+                    source, selector, t => QueryableMethods.MaxWithoutSelector.MakeGenericMethod(t), throwWhenEmpty: true, resultType);
 
     /// <inheritdoc />
     protected override ShapedQueryExpression? TranslateMin(ShapedQueryExpression source, LambdaExpression? selector, Type resultType)
-        => TranslateAggregateWithSelector(
-            source, selector, t => QueryableMethods.MinWithoutSelector.MakeGenericMethod(t), throwWhenEmpty: true, resultType);
+        => TryExtractBareInlineCollectionValues(source, out var values)
+            && _sqlExpressionFactory.TryCreateLeast(values, resultType, out var leastExpression)
+                ? source.Update(_sqlExpressionFactory.Select(leastExpression), source.ShaperExpression)
+                : TranslateAggregateWithSelector(
+                    source, selector, t => QueryableMethods.MinWithoutSelector.MakeGenericMethod(t), throwWhenEmpty: true, resultType);
 
     /// <inheritdoc />
     protected override ShapedQueryExpression? TranslateOfType(ShapedQueryExpression source, Type resultType)
@@ -2612,6 +2590,46 @@ private bool TryGetProjection(ShapedQueryExpression shapedQueryExpression, [NotN
         return false;
     }
 
+    private bool TryExtractBareInlineCollectionValues(ShapedQueryExpression shapedQuery, [NotNullWhen(true)] out SqlExpression[]? values)
+    {
+        if (TryGetProjection(shapedQuery, out var projection)
+            && shapedQuery.QueryExpression is SelectExpression
+            {
+                Tables:
+                [
+                    ValuesExpression
+                    {
+                        RowValues: [{ Values.Count: 2 }, ..],
+                        ColumnNames: [ValuesOrderingColumnName, ValuesValueColumnName]
+                    } valuesExpression
+                ],
+                Predicate: null,
+                GroupBy: [],
+                Having: null,
+                IsDistinct: false,
+                Limit: null,
+                Offset: null,
+                // Note that we assume ordering doesn't matter (Contains/Min/Max)
+            }
+            // Make sure that the source projects the column from the ValuesExpression directly, i.e. no projection out with some expression
+            && projection is ColumnExpression projectedColumn
+            && projectedColumn.Table == valuesExpression)
+        {
+            values = new SqlExpression[valuesExpression.RowValues.Count];
+
+            for (var i = 0; i < values.Length; i++)
+            {
+                // Skip the first value (_ord) - this function assumes ordering doesn't matter
+                values[i] = valuesExpression.RowValues[i].Values[1];
+            }
+
+            return true;
+        }
+
+        values = null;
+        return false;
+    }
+
     /// <summary>
     ///     A visitor which scans an expression tree and attempts to find columns for which we were missing type mappings (projected out
     ///     of queryable constant/parameter), and those type mappings have been inferred.

src/EFCore.Relational/Query/RelationalSqlTranslatingExpressionVisitor.cs

@@ -51,6 +51,12 @@ private static readonly MethodInfo StringEqualsWithStringComparison
     private static readonly MethodInfo StringEqualsWithStringComparisonStatic
         = typeof(string).GetRuntimeMethod(nameof(string.Equals), new[] { typeof(string), typeof(string), typeof(StringComparison) })!;
 
+    private static readonly MethodInfo LeastMethodInfo
+        = typeof(RelationalDbFunctionsExtensions).GetMethod(nameof(RelationalDbFunctionsExtensions.Least))!;
+
+    private static readonly MethodInfo GreatestMethodInfo
+        = typeof(RelationalDbFunctionsExtensions).GetMethod(nameof(RelationalDbFunctionsExtensions.Greatest))!;
+
     private static readonly MethodInfo GetTypeMethodInfo = typeof(object).GetTypeInfo().GetDeclaredMethod(nameof(GetType))!;
 
     private readonly QueryCompilationContext _queryCompilationContext;
@@ -932,6 +938,47 @@ protected override Expression VisitMethodCall(MethodCallExpression methodCallExp
                 return QueryCompilationContext.NotTranslatedExpression;
             }
         }
+        // Translate EF.Functions.Greatest/Least.
+        // These are here rather than in a MethodTranslator since the parameter is an array, and that's not supported in regular
+        // translation.
+        else if (method.DeclaringType == typeof(RelationalDbFunctionsExtensions)
+                 && method.IsGenericMethod
+                 && method.GetGenericMethodDefinition() is var genericMethodDefinition
+                 && (genericMethodDefinition == LeastMethodInfo || genericMethodDefinition == GreatestMethodInfo)
+                 && methodCallExpression.Arguments[1] is NewArrayExpression newArray)
+        {
+            var values = newArray.Expressions;
+            var translatedValues = new SqlExpression[values.Count];
+
+            for (var i = 0; i < values.Count; i++)
+            {
+                var value = values[i];
+                var visitedValue = Visit(value);
+
+                if (TranslationFailed(value, visitedValue, out var translatedValue))
+                {
+                    return QueryCompilationContext.NotTranslatedExpression;
+                }
+
+                translatedValues[i] = translatedValue!;
+            }
+
+            var elementClrType = newArray.Type.GetElementType()!;
+
+            if (genericMethodDefinition == LeastMethodInfo
+                && _sqlExpressionFactory.TryCreateLeast(translatedValues, elementClrType, out var leastExpression))
+            {
+                return leastExpression;
+            }
+
+            if (genericMethodDefinition == GreatestMethodInfo
+                && _sqlExpressionFactory.TryCreateGreatest(translatedValues, elementClrType, out var greatestExpression))
+            {
+                return greatestExpression;
+            }
+
+            throw new UnreachableException();
+        }
         else
         {
             if (method.IsStatic

src/EFCore.Relational/Query/SqlExpressionFactory.cs

@@ -675,6 +675,30 @@ public virtual SelectExpression Select(IEntityType entityType, TableExpressionBa
         return selectExpression;
     }
 
+    /// <inheritdoc />
+    public virtual bool TryCreateLeast(
+        IReadOnlyList<SqlExpression> expressions,
+        Type resultType,
+        [NotNullWhen(true)] out SqlExpression? leastExpression)
+    {
+        var resultTypeMapping = ExpressionExtensions.InferTypeMapping(expressions);
+        leastExpression = Function(
+            "LEAST", expressions, nullable: true, Enumerable.Repeat(true, expressions.Count), resultType, resultTypeMapping);
+        return true;
+    }
+
+    /// <inheritdoc />
+    public virtual bool TryCreateGreatest(
+        IReadOnlyList<SqlExpression> expressions,
+        Type resultType,
+        [NotNullWhen(true)] out SqlExpression? greatestExpression)
+    {
+        var resultTypeMapping = ExpressionExtensions.InferTypeMapping(expressions);
+        greatestExpression = Function(
+            "GREATEST", expressions, nullable: true, Enumerable.Repeat(true, expressions.Count), resultType, resultTypeMapping);
+        return true;
+    }
+
     /***
      * We need to add additional conditions on basic SelectExpression for certain cases
      * - If we are selecting from TPH then we need to add condition for discriminator if mapping is incomplete

src/EFCore.SqlServer/Properties/SqlServerStrings.Designer.cs

@@ -165,6 +165,9 @@
   <data name="DuplicateKeyMismatchedClustering" xml:space="preserve">
     <value>The keys {key1} on '{entityType1}' and {key2} on '{entityType2}' are both mapped to '{table}.{keyName}', but have different clustering configurations.</value>
   </data>
+  <data name="LeastGreatestCompatibilityLevelTooLow" xml:space="preserve">
+    <value>This usage of Math.Min or Math.Max requires SQL Server functions LEAST and GREATEST, which require compatibility level 160.</value>
+  </data>
   <data name="IdentityBadType" xml:space="preserve">
     <value>Identity value generation cannot be used for the property '{property}' on entity type '{entityType}' because the property type is '{propertyType}'. Identity value generation can only be used with signed integer properties.</value>
   </data>

src/EFCore.SqlServer/Properties/SqlServerStrings.resx

@@ -2,6 +2,8 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using Microsoft.EntityFrameworkCore.Query.SqlExpressions;
+using Microsoft.EntityFrameworkCore.SqlServer.Infrastructure.Internal;
+using Microsoft.EntityFrameworkCore.SqlServer.Internal;
 using ExpressionExtensions = Microsoft.EntityFrameworkCore.Query.ExpressionExtensions;
 
 namespace Microsoft.EntityFrameworkCore.SqlServer.Query.Internal;
@@ -186,6 +188,31 @@ public SqlServerMathTranslator(ISqlExpressionFactory sqlExpressionFactory)
             return _sqlExpressionFactory.ApplyTypeMapping(result, argument.TypeMapping);
         }
 
+        if (method.DeclaringType == typeof(Math))
+        {
+            if (method.Name == nameof(Math.Min))
+            {
+                if (_sqlExpressionFactory.TryCreateLeast(
+                        new[] { arguments[0], arguments[1] }, method.ReturnType, out var leastExpression))
+                {
+                    return leastExpression;
+                }
+
+                throw new InvalidOperationException(SqlServerStrings.LeastGreatestCompatibilityLevelTooLow);
+            }
+
+            if (method.Name == nameof(Math.Max))
+            {
+                if (_sqlExpressionFactory.TryCreateGreatest(
+                        new[] { arguments[0], arguments[1] }, method.ReturnType, out var leastExpression))
+                {
+                    return leastExpression;
+                }
+
+                throw new InvalidOperationException(SqlServerStrings.LeastGreatestCompatibilityLevelTooLow);
+            }
+        }
+
         return null;
     }
 }

src/EFCore.SqlServer/Query/Internal/SqlServerMathTranslator.cs

@@ -1,6 +1,8 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using Microsoft.EntityFrameworkCore.SqlServer.Infrastructure.Internal;
+
 namespace Microsoft.EntityFrameworkCore.SqlServer.Query.Internal;
 
 /// <summary>