diff --git a/src/Umbraco.Core/Persistence/Migrations/Upgrades/TargetVersionSevenTwelveZero/IncreaseLanguageIsoCodeColumnLength.cs b/src/Umbraco.Core/Persistence/Migrations/Upgrades/TargetVersionSevenTwelveZero/IncreaseLanguageIsoCodeColumnLength.cs
index 78b8602cc8..9d1806d075 100644
--- a/src/Umbraco.Core/Persistence/Migrations/Upgrades/TargetVersionSevenTwelveZero/IncreaseLanguageIsoCodeColumnLength.cs
+++ b/src/Umbraco.Core/Persistence/Migrations/Upgrades/TargetVersionSevenTwelveZero/IncreaseLanguageIsoCodeColumnLength.cs
@@ -17,33 +17,18 @@ namespace Umbraco.Core.Persistence.Migrations.Upgrades.TargetVersionSevenTwelveZ
         {
             // Some people seem to have a constraint in their DB instead of an index, we'd need to drop that one
             // See: https://our.umbraco.com/forum/using-umbraco-and-getting-started/93282-upgrade-from-711-to-712-fails
-            var constraints = SqlSyntax.GetConstraintsPerColumn(Context.Database).Distinct().Select(x => new ConstraintDefinition(ConstraintType.Unique)
-            {
-                TableName = x.Item1,
-                SchemaName = x.Item2,
-                ConstraintName = x.Item3
-            }).ToArray();
-
-            if (constraints.Any(x => x.ConstraintName.InvariantEquals("IX_umbracoLanguage_languageISOCode")))
+            var constraints = SqlSyntax.GetConstraintsPerTable(Context.Database).Distinct().ToArray();
+            if (constraints.Any(x => x.Item2.InvariantEquals("IX_umbracoLanguage_languageISOCode")))
             {
                 Delete.UniqueConstraint("IX_umbracoLanguage_languageISOCode").FromTable("umbracoLanguage");
             }
-            else
-            {
-                var dbIndexes = SqlSyntax.GetDefinedIndexes(Context.Database)
-                    .Select(x => new DbIndexDefinition()
-                    {
-                        TableName = x.Item1,
-                        IndexName = x.Item2,
-                        ColumnName = x.Item3,
-                        IsUnique = x.Item4
-                    }).ToArray();
 
-                //Ensure the index exists before dropping it
-                if (dbIndexes.Any(x => x.IndexName.InvariantEquals("IX_umbracoLanguage_languageISOCode")))
-                {
-                    Delete.Index("IX_umbracoLanguage_languageISOCode").OnTable("umbracoLanguage");
-                }
+            //Now check for indexes of that name and drop that if it exists
+            var dbIndexes = SqlSyntax.GetDefinedIndexes(Context.Database)
+                .Select(x => new DbIndexDefinition(x)).ToArray();
+            if (dbIndexes.Any(x => x.IndexName.InvariantEquals("IX_umbracoLanguage_languageISOCode")))
+            {
+                Delete.Index("IX_umbracoLanguage_languageISOCode").OnTable("umbracoLanguage");
             }
 
             Alter.Table("umbracoLanguage")
diff --git a/src/Umbraco.Core/Persistence/SqlSyntax/ISqlSyntaxProvider.cs b/src/Umbraco.Core/Persistence/SqlSyntax/ISqlSyntaxProvider.cs
index 366376b953..458853309c 100644
--- a/src/Umbraco.Core/Persistence/SqlSyntax/ISqlSyntaxProvider.cs
+++ b/src/Umbraco.Core/Persistence/SqlSyntax/ISqlSyntaxProvider.cs
@@ -78,9 +78,32 @@ namespace Umbraco.Core.Persistence.SqlSyntax
 
         IEnumerable<string> GetTablesInSchema(Database db);
         IEnumerable<ColumnInfo> GetColumnsInSchema(Database db);
+
+        /// <summary>
+        /// Returns all constraints defined in the database (Primary keys, foreign keys, unique constraints...) (does not include indexes)
+        /// </summary>
+        /// <param name="db"></param>
+        /// <returns>
+        /// A Tuple containing: TableName, ConstraintName
+        /// </returns>
         IEnumerable<Tuple<string, string>> GetConstraintsPerTable(Database db);
+
+        /// <summary>
+        /// Returns all constraints defined in the database (Primary keys, foreign keys, unique constraints...) (does not include indexes)
+        /// </summary>
+        /// <param name="db"></param>
+        /// <returns>
+        /// A Tuple containing: TableName, ColumnName, ConstraintName
+        /// </returns>
         IEnumerable<Tuple<string, string, string>> GetConstraintsPerColumn(Database db);
 
+        /// <summary>
+        /// Returns all defined Indexes in the database excluding primary keys
+        /// </summary>
+        /// <param name="db"></param>
+        /// <returns>
+        /// A Tuple containing: TableName, IndexName, ColumnName, IsUnique
+        /// </returns>
         IEnumerable<Tuple<string, string, string, bool>> GetDefinedIndexes(Database db);
     }
-}
\ No newline at end of file
+}
diff --git a/src/Umbraco.Core/Persistence/SqlSyntax/MySqlSyntaxProvider.cs b/src/Umbraco.Core/Persistence/SqlSyntax/MySqlSyntaxProvider.cs
index ceb8e9c83f..c3ad8f48c4 100644
--- a/src/Umbraco.Core/Persistence/SqlSyntax/MySqlSyntaxProvider.cs
+++ b/src/Umbraco.Core/Persistence/SqlSyntax/MySqlSyntaxProvider.cs
@@ -78,6 +78,7 @@ namespace Umbraco.Core.Persistence.SqlSyntax
             return list;
         }
 
+        /// <inheritdoc />
         public override IEnumerable<Tuple<string, string>> GetConstraintsPerTable(Database db)
         {
             List<Tuple<string, string>> list;
@@ -100,6 +101,7 @@ namespace Umbraco.Core.Persistence.SqlSyntax
             return list;
         }
 
+        /// <inheritdoc />
         public override IEnumerable<Tuple<string, string, string>> GetConstraintsPerColumn(Database db)
         {
             List<Tuple<string, string, string>> list;
@@ -126,6 +128,7 @@ namespace Umbraco.Core.Persistence.SqlSyntax
             return list;
         }
 
+        /// <inheritdoc />
         public override IEnumerable<Tuple<string, string, string, bool>> GetDefinedIndexes(Database db)
         {
             List<Tuple<string, string, string, bool>> list;
@@ -401,4 +404,4 @@ ORDER BY TABLE_NAME, INDEX_NAME",
             return PetaPocoExtensions.EscapeAtSymbols(MySql.Data.MySqlClient.MySqlHelper.EscapeString(val));
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/Umbraco.Core/Persistence/SqlSyntax/SqlCeSyntaxProvider.cs b/src/Umbraco.Core/Persistence/SqlSyntax/SqlCeSyntaxProvider.cs
index 69ebe11a14..8c083eaf1f 100644
--- a/src/Umbraco.Core/Persistence/SqlSyntax/SqlCeSyntaxProvider.cs
+++ b/src/Umbraco.Core/Persistence/SqlSyntax/SqlCeSyntaxProvider.cs
@@ -123,40 +123,27 @@ namespace Umbraco.Core.Persistence.SqlSyntax
                                    item.IS_NULLABLE, item.DATA_TYPE)).ToList();
         }
 
+        /// <inheritdoc />
         public override IEnumerable<Tuple<string, string>> GetConstraintsPerTable(Database db)
         {
             var items = db.Fetch<dynamic>("SELECT TABLE_NAME, CONSTRAINT_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS");
-            var indexItems = db.Fetch<dynamic>("SELECT TABLE_NAME, INDEX_NAME FROM INFORMATION_SCHEMA.INDEXES");
-            return
-                items.Select(item => new Tuple<string, string>(item.TABLE_NAME, item.CONSTRAINT_NAME))
-                     .Union(
-                         indexItems.Select(
-                             indexItem => new Tuple<string, string>(indexItem.TABLE_NAME, indexItem.INDEX_NAME)))
-                     .ToList();
+            return items.Select(item => new Tuple<string, string>(item.TABLE_NAME, item.CONSTRAINT_NAME)).ToList();
         }
 
+        /// <inheritdoc />
         public override IEnumerable<Tuple<string, string, string>> GetConstraintsPerColumn(Database db)
         {
-            var items =
-                db.Fetch<dynamic>(
-                    "SELECT CONSTRAINT_NAME, TABLE_NAME, COLUMN_NAME FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE");
-            var indexItems = db.Fetch<dynamic>("SELECT INDEX_NAME, TABLE_NAME, COLUMN_NAME FROM INFORMATION_SCHEMA.INDEXES");
-            return
-                items.Select(
-                    item => new Tuple<string, string, string>(item.TABLE_NAME, item.COLUMN_NAME, item.CONSTRAINT_NAME))
-                     .Union(
-                         indexItems.Select(
-                             indexItem =>
-                             new Tuple<string, string, string>(indexItem.TABLE_NAME, indexItem.COLUMN_NAME,
-                                                               indexItem.INDEX_NAME))).ToList();
+            var items = db.Fetch<dynamic>("SELECT TABLE_NAME, COLUMN_NAME, CONSTRAINT_NAME FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE");
+            return items.Select(item => new Tuple<string, string, string>(item.TABLE_NAME, item.COLUMN_NAME, item.CONSTRAINT_NAME)).ToList();
         }
 
+        /// <inheritdoc />
         public override IEnumerable<Tuple<string, string, string, bool>> GetDefinedIndexes(Database db)
         {
             var items =
                 db.Fetch<dynamic>(
                     @"SELECT TABLE_NAME, INDEX_NAME, COLUMN_NAME, [UNIQUE] FROM INFORMATION_SCHEMA.INDEXES 
-WHERE INDEX_NAME NOT LIKE 'PK_%'
+WHERE PRIMARY_KEY=0
 ORDER BY TABLE_NAME, INDEX_NAME");
             return
                 items.Select(
@@ -215,4 +202,4 @@ ORDER BY TABLE_NAME, INDEX_NAME");
         public override string DropIndex { get { return "DROP INDEX {1}.{0}"; } }
         
     }
-}
\ No newline at end of file
+}
diff --git a/src/Umbraco.Core/Persistence/SqlSyntax/SqlServerSyntaxProvider.cs b/src/Umbraco.Core/Persistence/SqlSyntax/SqlServerSyntaxProvider.cs
index 6cc97bdfb3..2258268631 100644
--- a/src/Umbraco.Core/Persistence/SqlSyntax/SqlServerSyntaxProvider.cs
+++ b/src/Umbraco.Core/Persistence/SqlSyntax/SqlServerSyntaxProvider.cs
@@ -88,6 +88,7 @@ namespace Umbraco.Core.Persistence.SqlSyntax
                                    item.IS_NULLABLE, item.DATA_TYPE)).ToList();
         }
 
+        /// <inheritdoc />
         public override IEnumerable<Tuple<string, string>> GetConstraintsPerTable(Database db)
         {
             var items =
@@ -96,6 +97,7 @@ namespace Umbraco.Core.Persistence.SqlSyntax
             return items.Select(item => new Tuple<string, string>(item.TABLE_NAME, item.CONSTRAINT_NAME)).ToList();
         }
 
+        /// <inheritdoc />
         public override IEnumerable<Tuple<string, string, string>> GetConstraintsPerColumn(Database db)
         {
             var items =
@@ -104,6 +106,7 @@ namespace Umbraco.Core.Persistence.SqlSyntax
             return items.Select(item => new Tuple<string, string, string>(item.TABLE_NAME, item.COLUMN_NAME, item.CONSTRAINT_NAME)).ToList();
         }
 
+        /// <inheritdoc />
         public override IEnumerable<Tuple<string, string, string, bool>> GetDefinedIndexes(Database db)
         {
             var items =
@@ -113,7 +116,7 @@ CASE WHEN I.is_unique_constraint = 1 OR  I.is_unique = 1 THEN 1 ELSE 0 END AS [U
 from sys.tables as T inner join sys.indexes as I on T.[object_id] = I.[object_id] 
    inner join sys.index_columns as IC on IC.[object_id] = I.[object_id] and IC.[index_id] = I.[index_id] 
    inner join sys.all_columns as AC on IC.[object_id] = AC.[object_id] and IC.[column_id] = AC.[column_id] 
-WHERE I.name NOT LIKE 'PK_%'
+WHERE I.is_primary_key = 0
 order by T.name, I.name");
             return items.Select(item => new Tuple<string, string, string, bool>(item.TABLE_NAME, item.INDEX_NAME, item.COLUMN_NAME,
                 item.UNIQUE == 1)).ToList();
@@ -183,4 +186,4 @@ order by T.name, I.name");
 
 
     }
-}
\ No newline at end of file
+}