Fix version detection for RENAME INDEX support. Fixes #15931.

activerecord/CHANGELOG.md

@@ -1,3 +1,9 @@
+*   Do not use `RENAME INDEX` syntax for MariaDB 10.0.
+
+    Fixes #15931.
+
+    *Jeff Browning*
+
 *   Fix the schema dump generated for tables without constraints and with
     primary key with default value of custom PostgreSQL function result.
 

activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb

@@ -473,7 +473,7 @@ def drop_table(table_name, options = {})
       end
 
       def rename_index(table_name, old_name, new_name)
-        if (version[0] == 5 && version[1] >= 7) || version[0] >= 6
+        if supports_rename_index?
           execute "ALTER TABLE #{quote_table_name(table_name)} RENAME INDEX #{quote_table_name(old_name)} TO #{quote_table_name(new_name)}"
         else
           super
@@ -774,10 +774,22 @@ def remove_timestamps_sql(table_name)
 
       private
 
+      def version
+        @version ||= full_version.scan(/^(\d+)\.(\d+)\.(\d+)/).flatten.map { |v| v.to_i }
+      end
+
+      def mariadb?
+        !!(full_version =~ /mariadb/i)
+      end
+
       def supports_views?
         version[0] >= 5
       end
 
+      def supports_rename_index?
+        mariadb? ? false : (version[0] == 5 && version[1] >= 7) || version[0] >= 6
+      end
+
       def configure_connection
         variables = @config.fetch(:variables, {}).stringify_keys
 

activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb

@@ -269,8 +269,8 @@ def configure_connection
         super
       end
 
-      def version
-        @version ||= @connection.info[:version].scan(/^(\d+)\.(\d+)\.(\d+)/).flatten.map { |v| v.to_i }
+      def full_version
+        @full_version ||= @connection.info[:version]
       end
 
       def set_field_encoding field_name

activerecord/lib/active_record/connection_adapters/mysql_adapter.rb

@@ -470,9 +470,9 @@ def select(sql, name = nil, binds = [])
         rows
       end
 
-      # Returns the version of the connected MySQL server.
-      def version
-        @version ||= @connection.server_info.scan(/^(\d+)\.(\d+)\.(\d+)/).flatten.map { |v| v.to_i }
+      # Returns the full version of the connected MySQL server.
+      def full_version
+        @full_version ||= @connection.server_info
       end
 
       def set_field_encoding field_name