Don't add an IS NOT NULL filter to unique indexes on required TPT and TPC columns on SQL Server

src/EFCore.SqlServer/EFCore.SqlServer.baseline.json

@@ -1461,11 +1461,14 @@
       ]
     },
     {
-      "Type": "class Microsoft.EntityFrameworkCore.Metadata.Conventions.SqlServerIndexConvention : Microsoft.EntityFrameworkCore.Metadata.Conventions.IEntityTypeBaseTypeChangedConvention, Microsoft.EntityFrameworkCore.Metadata.Conventions.IConvention, Microsoft.EntityFrameworkCore.Metadata.Conventions.IIndexAddedConvention, Microsoft.EntityFrameworkCore.Metadata.Conventions.IIndexUniquenessChangedConvention, Microsoft.EntityFrameworkCore.Metadata.Conventions.IIndexAnnotationChangedConvention, Microsoft.EntityFrameworkCore.Metadata.Conventions.IPropertyNullabilityChangedConvention, Microsoft.EntityFrameworkCore.Metadata.Conventions.IPropertyAnnotationChangedConvention",
+      "Type": "class Microsoft.EntityFrameworkCore.Metadata.Conventions.SqlServerIndexConvention : Microsoft.EntityFrameworkCore.Metadata.Conventions.IEntityTypeBaseTypeChangedConvention, Microsoft.EntityFrameworkCore.Metadata.Conventions.IConvention, Microsoft.EntityFrameworkCore.Metadata.Conventions.IDiscriminatorPropertySetConvention, Microsoft.EntityFrameworkCore.Metadata.Conventions.IIndexAddedConvention, Microsoft.EntityFrameworkCore.Metadata.Conventions.IIndexUniquenessChangedConvention, Microsoft.EntityFrameworkCore.Metadata.Conventions.IIndexAnnotationChangedConvention, Microsoft.EntityFrameworkCore.Metadata.Conventions.IPropertyNullabilityChangedConvention, Microsoft.EntityFrameworkCore.Metadata.Conventions.IPropertyAnnotationChangedConvention",
       "Methods": [
         {
           "Member": "SqlServerIndexConvention(Microsoft.EntityFrameworkCore.Metadata.Conventions.Infrastructure.ProviderConventionSetBuilderDependencies dependencies, Microsoft.EntityFrameworkCore.Metadata.Conventions.Infrastructure.RelationalConventionSetBuilderDependencies relationalDependencies, Microsoft.EntityFrameworkCore.Storage.ISqlGenerationHelper sqlGenerationHelper);"
         },
+        {
+          "Member": "virtual void ProcessDiscriminatorPropertySet(Microsoft.EntityFrameworkCore.Metadata.Builders.IConventionTypeBaseBuilder structuralTypeBuilder, string? name, Microsoft.EntityFrameworkCore.Metadata.Conventions.IConventionContext<string?> context);"
+        },
         {
           "Member": "virtual void ProcessEntityTypeBaseTypeChanged(Microsoft.EntityFrameworkCore.Metadata.Builders.IConventionEntityTypeBuilder entityTypeBuilder, Microsoft.EntityFrameworkCore.Metadata.IConventionEntityType? newBaseType, Microsoft.EntityFrameworkCore.Metadata.IConventionEntityType? oldBaseType, Microsoft.EntityFrameworkCore.Metadata.Conventions.IConventionContext<Microsoft.EntityFrameworkCore.Metadata.IConventionEntityType> context);"
         },

src/EFCore.SqlServer/Metadata/Conventions/SqlServerIndexConvention.cs

@@ -18,6 +18,7 @@ namespace Microsoft.EntityFrameworkCore.Metadata.Conventions;
 /// </remarks>
 public class SqlServerIndexConvention :
     IEntityTypeBaseTypeChangedConvention,
+    IDiscriminatorPropertySetConvention,
     IIndexAddedConvention,
     IIndexUniquenessChangedConvention,
     IIndexAnnotationChangedConvention,
@@ -76,6 +77,34 @@ public virtual void ProcessEntityTypeBaseTypeChanged(
         }
     }
 
+    /// <summary>
+    ///     Called after a discriminator property is set.
+    /// </summary>
+    /// <param name="structuralTypeBuilder">The builder for the type.</param>
+    /// <param name="name">The name of the discriminator property.</param>
+    /// <param name="context">Additional information associated with convention execution.</param>
+    public virtual void ProcessDiscriminatorPropertySet(
+        IConventionTypeBaseBuilder structuralTypeBuilder,
+        string? name,
+        IConventionContext<string?> context)
+    {
+        if (structuralTypeBuilder is not IConventionEntityTypeBuilder entityTypeBuilder)
+        {
+            return;
+        }
+
+        // Whether the columns of derived types are nullable depends on the mapping strategy, which is only known
+        // for sure once the discriminator is removed for TPT and TPC hierarchies. Regenerate existing filters too, since
+        // the set of nullable columns may have shrunk; a filter configured explicitly is still not overridden.
+        foreach (var entityType in entityTypeBuilder.Metadata.GetDerivedTypesInclusive())
+        {
+            foreach (var index in entityType.GetDeclaredIndexes())
+            {
+                SetIndexFilter(index.Builder, regenerate: true);
+            }
+        }
+    }
+
     /// <summary>
     ///     Called after an index is added to the entity type.
     /// </summary>
@@ -151,19 +180,19 @@ public virtual void ProcessPropertyAnnotationChanged(
         {
             foreach (var index in propertyBuilder.Metadata.GetContainingIndexes())
             {
-                SetIndexFilter(index.Builder, columnNameChanged: true);
+                SetIndexFilter(index.Builder, regenerate: true);
             }
         }
     }
 
-    private void SetIndexFilter(IConventionIndexBuilder indexBuilder, bool columnNameChanged = false)
+    private void SetIndexFilter(IConventionIndexBuilder indexBuilder, bool regenerate = false)
     {
         var index = indexBuilder.Metadata;
         if (index.IsUnique
             && index.IsClustered() != true
             && GetNullableColumns(index) is { Count: > 0 } nullableColumns)
         {
-            if (columnNameChanged
+            if (regenerate
                 || index.GetFilter() == null)
             {
                 indexBuilder.HasFilter(CreateIndexFilter(nullableColumns));

test/EFCore.SqlServer.FunctionalTests/ModelBuilding/SqlServerModelBuilderTestBase.cs

@@ -495,6 +495,77 @@ public void Index_convention_sets_filter_for_unique_index_when_base_type_changed
             Assert.Null(index.GetFilter());
         }
 
+        [Fact] // #32689
+        public void Index_convention_does_not_set_filter_for_unique_index_on_required_property_in_TPT()
+        {
+            var modelBuilder = CreateModelBuilder();
+            modelBuilder.Ignore<Customer>();
+            modelBuilder.Entity<DetailsBase>().ToTable("DetailsBase");
+            modelBuilder.Entity<CustomerDetails>(b =>
+            {
+                b.ToTable("CustomerDetails");
+                b.HasIndex(e => e.CustomerId).IsUnique();
+            });
+
+            var model = modelBuilder.FinalizeModel();
+
+            var index = model.FindEntityType(typeof(CustomerDetails))!.GetDeclaredIndexes().Single();
+            Assert.Null(index.GetFilter());
+        }
+
+        [Fact] // #32689
+        public void Index_convention_does_not_set_filter_for_unique_index_on_required_property_in_TPC()
+        {
+            var modelBuilder = CreateModelBuilder();
+            modelBuilder.Ignore<Customer>();
+            modelBuilder.Entity<CustomerDetails>()
+                .HasIndex(e => e.CustomerId)
+                .IsUnique();
+            modelBuilder.Entity<DetailsBase>().UseTpcMappingStrategy();
+
+            var model = modelBuilder.FinalizeModel();
+
+            var index = model.FindEntityType(typeof(CustomerDetails))!.GetDeclaredIndexes().Single();
+            Assert.Null(index.GetFilter());
+        }
+
+        [Fact] // #32689
+        public void Index_convention_keeps_only_nullable_columns_in_filter_for_composite_unique_index_in_TPT()
+        {
+            var modelBuilder = CreateModelBuilder();
+            modelBuilder.Ignore<Customer>();
+            modelBuilder.Entity<DetailsBase>().ToTable("DetailsBase");
+            modelBuilder.Entity<CustomerDetails>(b =>
+            {
+                b.ToTable("CustomerDetails");
+                b.Property<string?>("Note");
+                b.HasIndex(nameof(CustomerDetails.CustomerId), "Note").IsUnique();
+            });
+
+            var model = modelBuilder.FinalizeModel();
+
+            var index = model.FindEntityType(typeof(CustomerDetails))!.GetDeclaredIndexes().Single();
+            Assert.Equal("[Note] IS NOT NULL", index.GetFilter());
+        }
+
+        [Fact] // #32689
+        public void Index_convention_keeps_only_nullable_columns_in_filter_for_composite_unique_index_in_TPC()
+        {
+            var modelBuilder = CreateModelBuilder();
+            modelBuilder.Ignore<Customer>();
+            modelBuilder.Entity<CustomerDetails>(b =>
+            {
+                b.Property<string?>("Note");
+                b.HasIndex(nameof(CustomerDetails.CustomerId), "Note").IsUnique();
+            });
+            modelBuilder.Entity<DetailsBase>().UseTpcMappingStrategy();
+
+            var model = modelBuilder.FinalizeModel();
+
+            var index = model.FindEntityType(typeof(CustomerDetails))!.GetDeclaredIndexes().Single();
+            Assert.Equal("[Note] IS NOT NULL", index.GetFilter());
+        }
+
         [Fact]
         public virtual void Can_override_TPC_with_TPH()
         {