2 files changed, 5 insertions, 4 deletions
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
index 654ed0250e..9004d86b04 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
@@ -934,13 +934,13 @@ module ActiveRecord
 
       def add_index_options(table_name, column_name, options = {}) #:nodoc:
         column_names = Array(column_name)
-        index_name   = index_name(table_name, column: column_names)
 
         options.assert_valid_keys(:unique, :order, :name, :where, :length, :internal, :using, :algorithm, :type)
 
-        index_type = options[:unique] ? "UNIQUE" : ""
         index_type = options[:type].to_s if options.key?(:type)
+        index_type ||= options[:unique] ? "UNIQUE" : ""
         index_name = options[:name].to_s if options.key?(:name)
+        index_name ||= index_name(table_name, column: column_names)
         max_index_length = options.fetch(:internal, false) ? index_name_length : allowed_index_name_length
 
         if options.key?(:algorithm)
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
index b123b5415b..09aee1f467 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -931,8 +931,9 @@ module ActiveRecord
       end
 
       def add_index_sql(table_name, column_name, options = {})
-        index_name, index_type, index_columns = add_index_options(table_name, column_name, options)
-        "ADD #{index_type} INDEX #{index_name} (#{index_columns})"
+        index_name, index_type, index_columns, _, index_algorithm, index_using = add_index_options(table_name, column_name, options)
+        index_algorithm[0, 0] = ", " if index_algorithm.present?
+        "ADD #{index_type} INDEX #{quote_column_name(index_name)} #{index_using} (#{index_columns})#{index_algorithm}"
       end
 
       def remove_index_sql(table_name, options = {})