+ execute "ALTER TABLE #{table_name} DROP CONSTRAINT #{constraint_name}"
+ end
+
+ def alter_primary_key(table_name, column_name, options = {})
+ constraint_name = "#{table_name}_pkey"
+ tmp_constraint_name = "#{table_name}_pkey_tmp"
+
+ options = options.merge(:name => tmp_constraint_name, :unique => true)
+
+ add_index(table_name, column_name, **options)
+ remove_primary_key table_name
+ set_primary_key table_name, tmp_constraint_name
+ rename_index table_name, tmp_constraint_name, constraint_name