private boolean usersTableUpgraded() {
    try {
      dbAccessor.getColumnType(USERS_TABLE, USERS_USER_TYPE_COLUMN);
      return false;
    } catch (SQLException e) {
      return true;
    }
  }
If the <code>users</code> table has not yet been migrated, create the <code>user_authentication</code>
table and generate relevant records for that table based on data in the <code>users</code> table.
<p>
The records in the new <code>user_authentication</code> table represent all of the types associated
with a given (case-insensitive) username.  If <code>UserA:LOCAL</code>, <code>usera:LOCAL</code> and
<code>usera:LDAP</code> exist in the original <code>users</code> table, three records will be created
in the <code>user_authentication</code> table: one for each t
to <code>Role1</code>, the three <code>adminprivilege</code> records will be merged into a single
record for <code>usera</code>.

@throws SQLException if an error occurs while executing SQL statements
ambari-server/src/main/java/org/apache/ambari/server/upgrade/UpgradeCatalog270.java