diff --git a/src/REstate.Engine.Repositories.EntityFrameworkCore/REstateDbContext.cs b/src/REstate.Engine.Repositories.EntityFrameworkCore/REstateDbContext.cs
index 178ef7e..b6d413e 100644
--- a/src/REstate.Engine.Repositories.EntityFrameworkCore/REstateDbContext.cs
+++ b/src/REstate.Engine.Repositories.EntityFrameworkCore/REstateDbContext.cs
@@ -85,6 +85,9 @@ protected override void OnModelCreating(ModelBuilder modelBuilder)
                 .HasMaxLength(450)
                 .IsRequired();
 
+            modelBuilder.Entity<MetadataEntry>()
+                .HasIndex(entry => entry.Key);
+
             modelBuilder.Entity<StateBagEntry>()
                 .HasKey(entry => new
                 {
diff --git a/src/REstate.EntityFrameworkCore.Migrations.SqlServer/Migrations/20190111035035_IndexMetadataEntriesKey.Designer.cs b/src/REstate.EntityFrameworkCore.Migrations.SqlServer/Migrations/20190111035035_IndexMetadataEntriesKey.Designer.cs
new file mode 100644
index 0000000..7339d30
--- /dev/null
+++ b/src/REstate.EntityFrameworkCore.Migrations.SqlServer/Migrations/20190111035035_IndexMetadataEntriesKey.Designer.cs
@@ -0,0 +1,118 @@
+// <auto-generated />
+using System;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Metadata;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+using REstate.Engine.Repositories.EntityFrameworkCore;
+
+namespace REstate.EntityFrameworkCore.Migrations.SqlServer.Migrations
+{
+    [DbContext(typeof(REstateDbContext))]
+    [Migration("20190111035035_IndexMetadataEntriesKey")]
+    partial class IndexMetadataEntriesKey
+    {
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder
+                .HasAnnotation("ProductVersion", "2.1.4-rtm-31024")
+                .HasAnnotation("Relational:MaxIdentifierLength", 128)
+                .HasAnnotation("SqlServer:ValueGenerationStrategy", SqlServerValueGenerationStrategy.IdentityColumn);
+
+            modelBuilder.Entity("REstate.Engine.Repositories.EntityFrameworkCore.Machine", b =>
+                {
+                    b.Property<string>("MachineId")
+                        .ValueGeneratedOnAdd()
+                        .HasMaxLength(450)
+                        .IsUnicode(false);
+
+                    b.Property<long>("CommitNumber")
+                        .IsConcurrencyToken();
+
+                    b.Property<byte[]>("SchematicBytes");
+
+                    b.Property<string>("SchematicName")
+                        .HasMaxLength(450)
+                        .IsUnicode(false);
+
+                    b.Property<string>("StateJson")
+                        .IsRequired()
+                        .IsUnicode(false);
+
+                    b.Property<DateTimeOffset>("UpdatedTime");
+
+                    b.HasKey("MachineId");
+
+                    b.ToTable("Machines");
+                });
+
+            modelBuilder.Entity("REstate.Engine.Repositories.EntityFrameworkCore.MetadataEntry", b =>
+                {
+                    b.Property<string>("MachineId")
+                        .HasMaxLength(450)
+                        .IsUnicode(false);
+
+                    b.Property<string>("Key")
+                        .HasMaxLength(450)
+                        .IsUnicode(false);
+
+                    b.Property<string>("Value");
+
+                    b.HasKey("MachineId", "Key");
+
+                    b.HasIndex("Key");
+
+                    b.ToTable("MetadataEntries");
+                });
+
+            modelBuilder.Entity("REstate.Engine.Repositories.EntityFrameworkCore.Schematic", b =>
+                {
+                    b.Property<string>("SchematicName")
+                        .ValueGeneratedOnAdd()
+                        .IsUnicode(false);
+
+                    b.Property<byte[]>("SchematicBytes");
+
+                    b.HasKey("SchematicName");
+
+                    b.ToTable("Schematics");
+                });
+
+            modelBuilder.Entity("REstate.Engine.Repositories.EntityFrameworkCore.StateBagEntry", b =>
+                {
+                    b.Property<string>("MachineId")
+                        .HasMaxLength(450)
+                        .IsUnicode(false);
+
+                    b.Property<string>("Key")
+                        .HasMaxLength(450)
+                        .IsUnicode(false);
+
+                    b.Property<string>("Value");
+
+                    b.HasKey("MachineId", "Key");
+
+                    b.ToTable("StateBagEntries");
+                });
+
+            modelBuilder.Entity("REstate.Engine.Repositories.EntityFrameworkCore.MetadataEntry", b =>
+                {
+                    b.HasOne("REstate.Engine.Repositories.EntityFrameworkCore.Machine")
+                        .WithMany("MetadataEntries")
+                        .HasForeignKey("MachineId")
+                        .OnDelete(DeleteBehavior.Cascade);
+                });
+
+            modelBuilder.Entity("REstate.Engine.Repositories.EntityFrameworkCore.StateBagEntry", b =>
+                {
+                    b.HasOne("REstate.Engine.Repositories.EntityFrameworkCore.Machine")
+                        .WithMany("StateBagEntries")
+                        .HasForeignKey("MachineId")
+                        .OnDelete(DeleteBehavior.Cascade);
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}
diff --git a/src/REstate.EntityFrameworkCore.Migrations.SqlServer/Migrations/20190111035035_IndexMetadataEntriesKey.cs b/src/REstate.EntityFrameworkCore.Migrations.SqlServer/Migrations/20190111035035_IndexMetadataEntriesKey.cs
new file mode 100644
index 0000000..9409d8e
--- /dev/null
+++ b/src/REstate.EntityFrameworkCore.Migrations.SqlServer/Migrations/20190111035035_IndexMetadataEntriesKey.cs
@@ -0,0 +1,33 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+namespace REstate.EntityFrameworkCore.Migrations.SqlServer.Migrations
+{
+    public partial class IndexMetadataEntriesKey : Migration
+    {
+        private const string SqlServer = "Microsoft.EntityFrameworkCore.SqlServer";
+
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            if (migrationBuilder.ActiveProvider == SqlServer)
+            {
+                migrationBuilder.Sql(@"CREATE NONCLUSTERED INDEX IX_MetadataEntries_Key
+ON [dbo].[MetadataEntries] ([Key])
+INCLUDE ([Value])");
+            }
+            else
+            {
+                migrationBuilder.CreateIndex(
+                    name: "IX_MetadataEntries_Key",
+                    table: "MetadataEntries",
+                    column: "Key");
+            }
+        }
+
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropIndex(
+                name: "IX_MetadataEntries_Key",
+                table: "MetadataEntries");
+        }
+    }
+}
diff --git a/src/REstate.EntityFrameworkCore.Migrations.SqlServer/Migrations/REstateDbContextModelSnapshot.cs b/src/REstate.EntityFrameworkCore.Migrations.SqlServer/Migrations/REstateDbContextModelSnapshot.cs
index f491a95..b4ead75 100644
--- a/src/REstate.EntityFrameworkCore.Migrations.SqlServer/Migrations/REstateDbContextModelSnapshot.cs
+++ b/src/REstate.EntityFrameworkCore.Migrations.SqlServer/Migrations/REstateDbContextModelSnapshot.cs
@@ -60,6 +60,8 @@ protected override void BuildModel(ModelBuilder modelBuilder)
 
                     b.HasKey("MachineId", "Key");
 
+                    b.HasIndex("Key");
+
                     b.ToTable("MetadataEntries");
                 });