sets limit 191 for schema_migrations#version in mysql2 if the encoding is "utf8mb4"

Please, see rationale in the included CHANGELOG patch.

1 files changed, 9 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb b/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb
index 20a5ca2baa..25b8aef617 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb
@@ -38,6 +38,15 @@ module ActiveRecord
         configure_connection
       end
 
+      MAX_INDEX_LENGTH_FOR_UTF8MB4 = 191
+      def initialize_schema_migrations_table
+        if @config[:encoding] == 'utf8mb4'
+          ActiveRecord::SchemaMigration.create_table(MAX_INDEX_LENGTH_FOR_UTF8MB4)
+        else
+          ActiveRecord::SchemaMigration.create_table
+        end
+      end
+
       def supports_explain?
         true
       end