enum data type for liquibase

I'm currently working on a liquibase.xml file to create table table_a. One of my fields is <column name="state" type="ENUM('yes','no')"> I'm using postgresql as my DBMS. is there anything like enum data type? I've read in this like http://wiki.postgresql.org/wiki/Enum

that postgresql doesn't have such data type. CREATE TYPE function is used to create this data type. I still don't know how to make it in liquibase though.

Any suggestions?

Well of course PostgreSQL has an enum type (which is clearly documented in the link you have shown and the manual).

I don't think Liquibase "natively" supports enums for PostgreSQL, but you should be able to achieve it with a custom SQL:

<changeSet id="1" author="Arthur">
  <sql>CREATE TYPE my_state AS ENUM ('yes','no')</sql>
  <table name="foo">
    <column name="state" type="my_state"/>
  </table>
</changeSet>

For a simple yes/no column, I'd actually use the boolean type instead of an enum

An alternative to creating a new type would be a simple CHECK constraint on a varchar(3) column:

<changeSet id="1" author="X">
    <table name="t">
        <column name="c" type="varchar(3)"/>
    </table>
    <sql>ALTER TABLE t ADD CONSTRAINT check_yes_no CHECK (c = 'yes' OR c = 'no')</sql>
</changeSet>

That might play better with the client side, or not. I think boolean (as suggested by a_horse_with_no_name) would be a better call for this specific case: saying exactly what you mean usually works out better than the alternatives.