diff --git a/src/Umbraco.Core/Models/Rdbms/DictionaryDto.cs b/src/Umbraco.Core/Models/Rdbms/DictionaryDto.cs
index 712d1937a9..1e1940ad8d 100644
--- a/src/Umbraco.Core/Models/Rdbms/DictionaryDto.cs
+++ b/src/Umbraco.Core/Models/Rdbms/DictionaryDto.cs
@@ -24,7 +24,8 @@ namespace Umbraco.Core.Models.Rdbms
         public Guid? Parent { get; set; }
 
         [Column("key")]
-        [Length(1000)]
+        [Length(450)]
+        [Index(IndexTypes.NonClustered, Name = "IX_cmsDictionary_key")]
         public string Key { get; set; }
 
         [ResultColumn]
diff --git a/src/Umbraco.Core/Persistence/Migrations/Upgrades/TargetVersionSevenSevenZero/AddIndexToDictionaryKeyColumn.cs b/src/Umbraco.Core/Persistence/Migrations/Upgrades/TargetVersionSevenSevenZero/AddIndexToDictionaryKeyColumn.cs
new file mode 100644
index 0000000000..8d708a18ea
--- /dev/null
+++ b/src/Umbraco.Core/Persistence/Migrations/Upgrades/TargetVersionSevenSevenZero/AddIndexToDictionaryKeyColumn.cs
@@ -0,0 +1,63 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Runtime.Remoting.Contexts;
+using System.Text;
+using System.Threading.Tasks;
+using Umbraco.Core.Logging;
+using Umbraco.Core.Persistence.SqlSyntax;
+
+namespace Umbraco.Core.Persistence.Migrations.Upgrades.TargetVersionSevenSevenZero
+{
+    [Migration("7.7.0", 5, Constants.System.UmbracoMigrationName)]
+    public class AddIndexToDictionaryKeyColumn : MigrationBase
+    {
+        public AddIndexToDictionaryKeyColumn(ISqlSyntaxProvider sqlSyntax, ILogger logger)
+            : base(sqlSyntax, logger)
+        { }
+
+        public override void Up()
+        {
+            Execute.Code(database =>
+            {
+                //Now we need to check if we can actually do this because we won't be able to if there's data in there that is too long
+                var colLen = (SqlSyntax is MySqlSyntaxProvider)
+                    ? database.ExecuteScalar<int?>(string.Format("select max(LENGTH({0})) from cmsDictionary", SqlSyntax.GetQuotedColumnName("key")))
+                    : database.ExecuteScalar<int?>(string.Format("select max(datalength({0})) from cmsDictionary", SqlSyntax.GetQuotedColumnName("key")));
+
+                if (colLen < 900 == false && colLen != null)
+                {
+                    return null;
+                }
+
+                var dbIndexes = SqlSyntax.GetDefinedIndexesDefinitions(Context.Database);
+
+                //make sure it doesn't already exist
+                if (dbIndexes.Any(x => x.IndexName.InvariantEquals("IX_cmsDictionary_key")) == false)
+                {
+                    var localContext = new LocalMigrationContext(Context.CurrentDatabaseProvider, database, SqlSyntax, Logger);
+
+                    //we can apply the index
+                    localContext.Create.Index("IX_cmsDictionary_key").OnTable("cmsDictionary")
+                        .OnColumn("key")
+                        .Ascending()
+                        .WithOptions()
+                        .NonClustered();
+
+                    return localContext.GetSql();
+                }
+
+                return null;
+
+            });
+
+
+        }
+
+        public override void Down()
+        {
+            Delete.Index("IX_cmsDictionary_key").OnTable("cmsDictionary");
+        }
+
+    }
+}
diff --git a/src/Umbraco.Core/Persistence/Migrations/Upgrades/TargetVersionSevenSevenZero/ReduceDictionaryKeyColumnsSize.cs b/src/Umbraco.Core/Persistence/Migrations/Upgrades/TargetVersionSevenSevenZero/ReduceDictionaryKeyColumnsSize.cs
new file mode 100644
index 0000000000..a707e4687a
--- /dev/null
+++ b/src/Umbraco.Core/Persistence/Migrations/Upgrades/TargetVersionSevenSevenZero/ReduceDictionaryKeyColumnsSize.cs
@@ -0,0 +1,51 @@
+using System.Linq;
+using Umbraco.Core.Logging;
+using Umbraco.Core.Persistence.SqlSyntax;
+
+namespace Umbraco.Core.Persistence.Migrations.Upgrades.TargetVersionSevenSevenZero
+{
+    [Migration("7.7.0", 4, Constants.System.UmbracoMigrationName)]
+    public class ReduceDictionaryKeyColumnsSize : MigrationBase
+    {
+        public ReduceDictionaryKeyColumnsSize(ISqlSyntaxProvider sqlSyntax, ILogger logger)
+            : base(sqlSyntax, logger)
+        { }
+
+        public override void Up()
+        {
+            //Now we need to check if we can actually do this because we won't be able to if there's data in there that is too long
+
+            Execute.Code(database =>
+            {
+                var dbIndexes = SqlSyntax.GetDefinedIndexesDefinitions(database);
+
+                var colLen = (SqlSyntax is MySqlSyntaxProvider)
+                    ? database.ExecuteScalar<int?>(string.Format("select max(LENGTH({0})) from cmsDictionary", SqlSyntax.GetQuotedColumnName("key")))
+                    : database.ExecuteScalar<int?>(string.Format("select max(datalength({0})) from cmsDictionary", SqlSyntax.GetQuotedColumnName("key")));
+
+                if (colLen < 900 == false) return null;
+
+                var localContext = new LocalMigrationContext(Context.CurrentDatabaseProvider, database, SqlSyntax, Logger);
+
+                //if it exists we need to drop it first
+                if (dbIndexes.Any(x => x.IndexName.InvariantEquals("IX_cmsDictionary_key")))
+                {
+                    localContext.Delete.Index("IX_cmsDictionary_key").OnTable("cmsDictionary");
+                }
+
+                //we can apply the col length change
+                localContext.Alter.Table("cmsDictionary")
+                    .AlterColumn("key")
+                    .AsString(450)
+                    .NotNullable();
+
+                return localContext.GetSql();
+            });
+        }
+
+        public override void Down()
+        {
+
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/Umbraco.Core/Umbraco.Core.csproj b/src/Umbraco.Core/Umbraco.Core.csproj
index d5a9ea33cc..5aa2383237 100644
--- a/src/Umbraco.Core/Umbraco.Core.csproj
+++ b/src/Umbraco.Core/Umbraco.Core.csproj
@@ -500,6 +500,8 @@
     <Compile Include="Persistence\Mappers\MigrationEntryMapper.cs" />
     <Compile Include="Persistence\Migrations\LocalMigrationContext.cs" />
     <Compile Include="Persistence\Migrations\Upgrades\TargetVersionFourOneZero\AddPreviewXmlTable.cs" />
+    <Compile Include="Persistence\Migrations\Upgrades\TargetVersionSevenSevenZero\AddIndexToDictionaryKeyColumn.cs" />
+    <Compile Include="Persistence\Migrations\Upgrades\TargetVersionSevenSevenZero\ReduceDictionaryKeyColumnsSize.cs" />
     <Compile Include="Persistence\Migrations\Upgrades\TargetVersionSevenSixZero\AddLockObjects.cs" />
     <Compile Include="Persistence\Migrations\Upgrades\TargetVersionSevenSixZero\AddLockTable.cs" />
     <Compile Include="Persistence\Migrations\Upgrades\TargetVersionSevenFiveFive\UpdateAllowedMediaTypesAtRoot.cs" />