Handle primitive collections as multiple parameters.

src/EFCore.Relational/Infrastructure/RelationalDbContextOptionsBuilder.cs

@@ -163,10 +163,9 @@ public virtual TBuilder ExecutionStrategy(
     /// </summary>
     /// <remarks>
     ///     <para>
-    ///         When a LINQ query contains a parameterized collection, by default EF Core parameterizes the entire collection as a single
-    ///         SQL parameter, if possible. For example, on SQL Server, the LINQ query <c>Where(b => ids.Contains(b.Id)</c> is translated to
-    ///         <c>WHERE [b].[Id] IN (SELECT [i].[value] FROM OPENJSON(@__ids_0) ...)</c>. While this helps with query plan caching, it can
-    ///         produce worse query plans for certain query types.
+    ///         When a LINQ query contains a parameterized collection, by default EF Core translates as a multiple SQL parameters,
+    ///         if possible. For example, on SQL Server, the LINQ query <c>Where(b => ids.Contains(b.Id)</c> is translated to
+    ///         <c>WHERE [b].[Id] IN (@ids1, @ids2, @ids3)</c>.
     ///     </para>
     ///     <para>
     ///         <see cref="TranslateParameterizedCollectionsToConstants" /> instructs EF to translate the collection to a set of constants:
@@ -176,37 +175,57 @@ public virtual TBuilder ExecutionStrategy(
     ///     <para>
     ///         Note that it's possible to cause EF to translate a specific collection in a specific query to constants by wrapping the
     ///         parameterized collection in <see cref="EF.Constant{T}" />: <c>Where(b => EF.Constant(ids).Contains(b.Id)</c>. This overrides
-    ///         the default. Likewise, you can translate a specific collection in a specific query to a single parameter by wrapping the
-    ///         parameterized collection in <see cref="EF.Parameter{T}(T)" />: <c>Where(b => EF.Parameter(ids).Contains(b.Id)</c>. This
-    ///         overrides the <see cref="TranslateParameterizedCollectionsToConstants" /> setting.
+    ///         the default.
     ///     </para>
     /// </remarks>
     public virtual TBuilder TranslateParameterizedCollectionsToConstants()
         => WithOption(e => (TExtension)e.WithParameterizedCollectionTranslationMode(ParameterizedCollectionTranslationMode.Constantize));
 
     /// <summary>
-    ///     Configures the context to translate parameterized collections to parameters.
+    ///     Configures the context to translate parameterized collections to parameter.
     /// </summary>
     /// <remarks>
     ///     <para>
-    ///         When a LINQ query contains a parameterized collection, by default EF Core parameterizes the entire collection as a single
-    ///         SQL parameter, if possible. For example, on SQL Server, the LINQ query <c>Where(b => ids.Contains(b.Id)</c> is translated to
-    ///         <c>WHERE [b].[Id] IN (SELECT [i].[value] FROM OPENJSON(@__ids_0) ...)</c>. While this helps with query plan caching, it can
-    ///         produce worse query plans for certain query types.
+    ///         When a LINQ query contains a parameterized collection, by default EF Core translates as a multiple SQL parameters,
+    ///         if possible. For example, on SQL Server, the LINQ query <c>Where(b => ids.Contains(b.Id)</c> is translated to
+    ///         <c>WHERE [b].[Id] IN (@ids1, @ids2, @ids3)</c>.
     ///     </para>
     ///     <para>
-    ///         <see cref="TranslateParameterizedCollectionsToParameters" /> explicitly instructs EF to perform the default translation
-    ///         of parameterized collections, which is translating them to parameters.
+    ///         <see cref="TranslateParameterizedCollectionsToParameters" /> instructs EF to translate the collection to a set of constants:
+    ///         <c>WHERE [b].[Id] IN (SELECT [i].[value] FROM OPENJSON(@ids) ...)</c>.
     ///     </para>
     ///     <para>
-    ///         Note that it's possible to cause EF to translate a specific collection in a specific query to constants by wrapping the
-    ///         parameterized collection in <see cref="EF.Constant{T}" />: <c>Where(b => EF.Constant(ids).Contains(b.Id)</c>. This overrides
+    ///         Note that it's possible to cause EF to translate a specific collection in a specific query to parameter by wrapping the
+    ///         parameterized collection in <see cref="EF.Parameter{T}" />: <c>Where(b => EF.Parameter(ids).Contains(b.Id)</c>. This overrides
     ///         the default.
     ///     </para>
     /// </remarks>
     public virtual TBuilder TranslateParameterizedCollectionsToParameters()
         => WithOption(e => (TExtension)e.WithParameterizedCollectionTranslationMode(ParameterizedCollectionTranslationMode.Parameterize));
 
+    /// <summary>
+    ///     Configures the context to translate parameterized collections to expanded parameters.
+    /// </summary>
+    /// <remarks>
+    ///     <para>
+    ///         When a LINQ query contains a parameterized collection, by default EF Core translates as a multiple SQL parameters,
+    ///         if possible. For example, on SQL Server, the LINQ query <c>Where(b => ids.Contains(b.Id)</c> is translated to
+    ///         <c>WHERE [b].[Id] IN (@ids1, @ids2, @ids3)</c>.
+    ///     </para>
+    ///     <para>
+    ///         <see cref="TranslateParameterizedCollectionsToExpandedParameters" /> instructs EF to translate the collection to a set of parameters:
+    ///         <c>WHERE [b].[Id] IN (@ids1, @ids2, @ids3)</c>.
+    ///     </para>
+    /// </remarks>
+    //TODO: When appropriate EF method is implemented, mention it here.
+    //     <para>
+    //         Note that it's possible to cause EF to translate a specific collection in a specific query to expanded parameters by wrapping the
+    //         parameterized collection in <see cref="EF.???{T}" />: <c>Where(b => EF.Parameter(ids).???(b.Id)</c>. This overrides
+    //         the default.
+    //     </para>
+    public virtual TBuilder TranslateParameterizedCollectionsToExpandedParameters()
+        => WithOption(e => (TExtension)e.WithParameterizedCollectionTranslationMode(ParameterizedCollectionTranslationMode.ParameterizeExpanded));
+
     /// <summary>
     ///     Sets an option by cloning the extension used to store the settings. This ensures the builder
     ///     does not modify options that are already in use elsewhere.

src/EFCore.Relational/Internal/ParameterizedCollectionTranslationMode.cs

@@ -26,4 +26,12 @@ public enum ParameterizedCollectionTranslationMode
     ///     doing so can result in application failures when updating to a new Entity Framework Core release.
     /// </summary>
     Parameterize,
+
+    /// <summary>
+    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+    ///     any release. You should only use it directly in your code with extreme caution and knowing that
+    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+    /// </summary>
+    ParameterizeExpanded,
 }

src/EFCore.Relational/Query/Internal/RelationalCommandCache.cs

@@ -3,6 +3,7 @@
 
 using System.Collections.Concurrent;
 using System.Runtime.CompilerServices;
+using Microsoft.EntityFrameworkCore.Internal;
 using Microsoft.Extensions.Caching.Memory;
 
 namespace Microsoft.EntityFrameworkCore.Query.Internal;
@@ -34,13 +35,14 @@ public RelationalCommandCache(
         IQuerySqlGeneratorFactory querySqlGeneratorFactory,
         IRelationalParameterBasedSqlProcessorFactory relationalParameterBasedSqlProcessorFactory,
         Expression queryExpression,
-        bool useRelationalNulls)
+        bool useRelationalNulls,
+        ParameterizedCollectionTranslationMode? parameterizedCollectionTranslationMode)
     {
         _memoryCache = memoryCache;
         _querySqlGeneratorFactory = querySqlGeneratorFactory;
         _queryExpression = queryExpression;
         _relationalParameterBasedSqlProcessor = relationalParameterBasedSqlProcessorFactory.Create(
-            new RelationalParameterBasedSqlProcessorParameters(useRelationalNulls));
+            new RelationalParameterBasedSqlProcessorParameters(useRelationalNulls, parameterizedCollectionTranslationMode));
     }
 
     /// <summary>
@@ -49,7 +51,7 @@ public RelationalCommandCache(
     ///     any release. You should only use it directly in your code with extreme caution and knowing that
     ///     doing so can result in application failures when updating to a new Entity Framework Core release.
     /// </summary>
-    public virtual IRelationalCommandTemplate GetRelationalCommandTemplate(IReadOnlyDictionary<string, object?> parameters)
+    public virtual IRelationalCommandTemplate GetRelationalCommandTemplate(Dictionary<string, object?> parameters)
     {
         var cacheKey = new CommandCacheKey(_queryExpression, parameters);
 

src/EFCore.Relational/Query/Internal/RelationalCommandResolver.cs

@@ -9,4 +9,4 @@ namespace Microsoft.EntityFrameworkCore.Query.Internal;
 ///     any release. You should only use it directly in your code with extreme caution and knowing that
 ///     doing so can result in application failures when updating to a new Entity Framework Core release.
 /// </summary>
-public delegate IRelationalCommandTemplate RelationalCommandResolver(IReadOnlyDictionary<string, object?> parameters);
+public delegate IRelationalCommandTemplate RelationalCommandResolver(Dictionary<string, object?> parameters);

src/EFCore.Relational/Query/RelationalParameterBasedSqlProcessor.cs

@@ -49,7 +49,7 @@ public RelationalParameterBasedSqlProcessor(
     /// <returns>An optimized query expression.</returns>
     public virtual Expression Optimize(
         Expression queryExpression,
-        IReadOnlyDictionary<string, object?> parametersValues,
+        Dictionary<string, object?> parametersValues,
         out bool canCache)
     {
         canCache = true;
@@ -72,7 +72,7 @@ public virtual Expression Optimize(
     /// <returns>A processed query expression.</returns>
     protected virtual Expression ProcessSqlNullability(
         Expression queryExpression,
-        IReadOnlyDictionary<string, object?> parametersValues,
+        Dictionary<string, object?> parametersValues,
         out bool canCache)
         => new SqlNullabilityProcessor(Dependencies, Parameters).Process(queryExpression, parametersValues, out canCache);
 

src/EFCore.Relational/Query/RelationalParameterBasedSqlProcessorParameters.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.Internal;
+
 namespace Microsoft.EntityFrameworkCore.Query;
 
 /// <summary>
@@ -13,11 +15,20 @@ public sealed record RelationalParameterBasedSqlProcessorParameters
     /// </summary>
     public bool UseRelationalNulls { get; init; }
 
+    /// <summary>
+    ///     A value indicating what translation mode should be used.
+    /// </summary>
+    public ParameterizedCollectionTranslationMode? ParameterizedCollectionTranslationMode { get; init; }
+
     /// <summary>
     ///     Creates a new instance of <see cref="RelationalParameterBasedSqlProcessorParameters" />.
     /// </summary>
     /// <param name="useRelationalNulls">A value indicating if relational nulls should be used.</param>
+    /// <param name="parameterizedCollectionTranslationMode">A value indicating what translation mode should be used.</param>
     [EntityFrameworkInternal]
-    public RelationalParameterBasedSqlProcessorParameters(bool useRelationalNulls)
-        => UseRelationalNulls = useRelationalNulls;
+    public RelationalParameterBasedSqlProcessorParameters(bool useRelationalNulls, ParameterizedCollectionTranslationMode? parameterizedCollectionTranslationMode)
+    {
+        UseRelationalNulls = useRelationalNulls;
+        ParameterizedCollectionTranslationMode = parameterizedCollectionTranslationMode;
+    }
 }

src/EFCore.Relational/Query/RelationalQueryableMethodTranslatingExpressionVisitor.cs

@@ -295,10 +295,10 @@ JsonScalarExpression jsonScalar
 
         var primitiveCollectionsBehavior = RelationalOptionsExtension.Extract(QueryCompilationContext.ContextOptions)
             .ParameterizedCollectionTranslationMode;
-
         var tableAlias = _sqlAliasManager.GenerateTableAlias(sqlParameterExpression.Name.TrimStart('_'));
+
         if (queryParameter.ShouldBeConstantized
-            || (primitiveCollectionsBehavior == ParameterizedCollectionTranslationMode.Constantize
+            || (primitiveCollectionsBehavior is ParameterizedCollectionTranslationMode.Constantize
                 && !queryParameter.ShouldNotBeConstantized))
         {
             var valuesExpression = new ValuesExpression(
@@ -313,6 +313,21 @@ JsonScalarExpression jsonScalar
                 sqlParameterExpression.IsNullable);
         }
 
+        if ((primitiveCollectionsBehavior is null or ParameterizedCollectionTranslationMode.ParameterizeExpanded)
+            && !queryParameter.ShouldNotBeConstantized)
+        {
+            var valuesExpression = new ValuesExpression(
+                tableAlias,
+                sqlParameterExpression,
+                [ValuesOrderingColumnName, ValuesValueColumnName]);
+            return CreateShapedQueryExpressionForValuesExpression(
+                valuesExpression,
+                tableAlias,
+                parameterQueryRootExpression.ElementType,
+                sqlParameterExpression.TypeMapping,
+                sqlParameterExpression.IsNullable);
+        }
+
         return TranslatePrimitiveCollection(sqlParameterExpression, property: null, tableAlias);
     }
 
@@ -569,16 +584,23 @@ protected override ShapedQueryExpression TranslateConcat(ShapedQueryExpression s
             return TranslateAny(source, anyLambda);
         }
 
-        // Pattern-match Contains over ValuesExpression, translating to simplified 'item IN (1, 2, 3)' with constant elements
+        var primitiveCollectionsBehavior = RelationalOptionsExtension.Extract(QueryCompilationContext.ContextOptions)
+            .ParameterizedCollectionTranslationMode;
+        // Pattern-match Contains over ValuesExpression, translating to simplified 'item IN (1, 2, 3)' with constant elements.
         if (TryExtractBareInlineCollectionValues(source, out var values, out var valuesParameter))
         {
-            var inExpression = (values, valuesParameter) switch
+            if (values is not null)
             {
-                (not null, null) => _sqlExpressionFactory.In(translatedItem, values),
-                (null, not null) => _sqlExpressionFactory.In(translatedItem, valuesParameter),
-                _ => throw new UnreachableException(),
-            };
-            return source.Update(new SelectExpression(inExpression, _sqlAliasManager), source.ShaperExpression);
+                var inExpression = _sqlExpressionFactory.In(translatedItem, values);
+                return source.Update(new SelectExpression(inExpression, _sqlAliasManager), source.ShaperExpression);
+            }
+            if (valuesParameter is not null
+                // Expanding parameters will happen in 2nd stage of query pipeline.
+                && primitiveCollectionsBehavior is not (null or ParameterizedCollectionTranslationMode.ParameterizeExpanded))
+            {
+                var inExpression = _sqlExpressionFactory.In(translatedItem, valuesParameter);
+                return source.Update(new SelectExpression(inExpression, _sqlAliasManager), source.ShaperExpression);
+            }
         }
 
         // Translate to IN with a subquery.

src/EFCore.Relational/Query/RelationalShapedQueryCompilingExpressionVisitor.cs

@@ -19,6 +19,7 @@ public partial class RelationalShapedQueryCompilingExpressionVisitor : ShapedQue
     private readonly bool _threadSafetyChecksEnabled;
     private readonly bool _detailedErrorsEnabled;
     private readonly bool _useRelationalNulls;
+    private readonly ParameterizedCollectionTranslationMode? _parameterizedCollectionTranslationMode;
     private readonly bool _isPrecompiling;
 
     private readonly RelationalParameterBasedSqlProcessor _relationalParameterBasedSqlProcessor;
@@ -54,14 +55,15 @@ public RelationalShapedQueryCompilingExpressionVisitor(
 
         _relationalParameterBasedSqlProcessor =
             relationalDependencies.RelationalParameterBasedSqlProcessorFactory.Create(
-                new RelationalParameterBasedSqlProcessorParameters(_useRelationalNulls));
+                new RelationalParameterBasedSqlProcessorParameters(_useRelationalNulls, _parameterizedCollectionTranslationMode));
         _querySqlGeneratorFactory = relationalDependencies.QuerySqlGeneratorFactory;
 
         _contextType = queryCompilationContext.ContextType;
         _tags = queryCompilationContext.Tags;
         _threadSafetyChecksEnabled = dependencies.CoreSingletonOptions.AreThreadSafetyChecksEnabled;
         _detailedErrorsEnabled = dependencies.CoreSingletonOptions.AreDetailedErrorsEnabled;
         _useRelationalNulls = RelationalOptionsExtension.Extract(queryCompilationContext.ContextOptions).UseRelationalNulls;
+        _parameterizedCollectionTranslationMode = RelationalOptionsExtension.Extract(queryCompilationContext.ContextOptions).ParameterizedCollectionTranslationMode;
         _isPrecompiling = queryCompilationContext.IsPrecompiling;
     }
 
@@ -497,15 +499,16 @@ private Expression CreateRelationalCommandResolverExpression(Expression queryExp
             RelationalDependencies.QuerySqlGeneratorFactory,
             RelationalDependencies.RelationalParameterBasedSqlProcessorFactory,
             queryExpression,
-            _useRelationalNulls);
+            _useRelationalNulls,
+            _parameterizedCollectionTranslationMode);
 
         var commandLiftableConstant = RelationalDependencies.RelationalLiftableConstantFactory.CreateLiftableConstant(
             relationalCommandCache,
             GenerateRelationalCommandCacheExpression(),
             "relationalCommandCache",
             typeof(RelationalCommandCache));
 
-        var parametersParameter = Parameter(typeof(IReadOnlyDictionary<string, object?>), "parameters");
+        var parametersParameter = Parameter(typeof(Dictionary<string, object?>), "parameters");
 
         return Lambda<RelationalCommandResolver>(
             Call(
@@ -542,7 +545,7 @@ bool TryGeneratePregeneratedCommandResolver(
                 return false;
             }
 
-            var parameterDictionaryParameter = Parameter(typeof(IReadOnlyDictionary<string, object?>), "parameters");
+            var parameterDictionaryParameter = Parameter(typeof(Dictionary<string, object?>), "parameters");
             var resultParameter = Parameter(typeof(IRelationalCommandTemplate), "result");
             Expression resolverBody;
             bool canCache;
@@ -657,7 +660,7 @@ static object GenerateNonNullParameterValue(Type type)
                 }
             }
 
-            Expression GenerateRelationalCommandExpression(IReadOnlyDictionary<string, object?> parameters, out bool canCache)
+            Expression GenerateRelationalCommandExpression(Dictionary<string, object?> parameters, out bool canCache)
             {
                 var queryExpression = _relationalParameterBasedSqlProcessor.Optimize(select, parameters, out canCache);
                 if (!canCache)
@@ -747,7 +750,8 @@ Expression<Func<RelationalMaterializerLiftableConstantContext, object>> Generate
                             MakeMemberAccess(contextParameter, _relationalDependenciesProperty),
                             _relationalDependenciesRelationalParameterBasedSqlProcessorFactoryProperty),
                         Constant(queryExpression),
-                        Constant(_useRelationalNulls)),
+                        Constant(_useRelationalNulls),
+                        Constant(_parameterizedCollectionTranslationMode, typeof(ParameterizedCollectionTranslationMode?))),
                     contextParameter);
         }
     }

src/EFCore.Relational/Query/SqlExpressions/ValuesExpression.cs

@@ -167,7 +167,7 @@ public override Expression Quote()
             Constant(Alias, typeof(string)),
             RowValues is not null
                 ? NewArrayInit(typeof(RowValueExpression), RowValues.Select(rv => rv.Quote()))
-                : Constant(null, typeof(RowValueExpression)),
+                : Constant(null, typeof(IReadOnlyList<RowValueExpression>)),
             RelationalExpressionQuotingUtilities.QuoteOrNull(ValuesParameter),
             NewArrayInit(typeof(string), ColumnNames.Select(Constant)),
             RelationalExpressionQuotingUtilities.QuoteAnnotations(Annotations));