PostgreSQL compatibility

I am using PostgreSQL. Following errors appear on system charts pages.

    * warning: pg_query() [function.pg-query]: Query failed: ERROR: function from_unixtime(integer, "unknown") does not exist LINE 4: WHERE FROM_UNIXTIME(created, '%Y %e') = FROM_UNIX... ^ HINT: No function matches the given name and argument types. You may need to add explicit type casts. in /home/mustafau/pdt_workspace/drupal/includes/database.pgsql.inc on line 125.
    * user warning: query: SELECT COUNT(*) as count, type FROM node WHERE FROM_UNIXTIME(created, '%Y %e') = FROM_UNIXTIME(UNIX_TIMESTAMP(), '%Y %e') GROUP BY type ORDER BY type in /home/mustafau/pdt_workspace/drupal/includes/database.pgsql.inc on line 144.
    * warning: pg_query() [function.pg-query]: Query failed: ERROR: function from_unixtime(integer, "unknown") does not exist LINE 4: FROM_UNIXTIME(created, '%D') as day_created, ^ HINT: No function matches the given name and argument types. You may need to add explicit type casts. in /home/mustafau/pdt_workspace/drupal/includes/database.pgsql.inc on line 125.
    * user warning: query: SELECT type, COUNT(*) as count, FROM_UNIXTIME(created, '%D') as day_created, FROM_UNIXTIME(created, '%Y %M') as time_created FROM node WHERE FROM_UNIXTIME(created, '%Y %M') = FROM_UNIXTIME(UNIX_TIMESTAMP(), '%Y %M') GROUP BY type, day_created ORDER BY created in /home/mustafau/pdt_workspace/drupal/includes/database.pgsql.inc on line 144.

    * warning: pg_query() [function.pg-query]: Query failed: ERROR: column "r.name" must appear in the GROUP BY clause or be used in an aggregate function in /home/mustafau/pdt_workspace/drupal/includes/database.pgsql.inc on line 125.
    * user warning: query: SELECT COUNT(*) as count, r.* FROM users_roles ur LEFT JOIN users u ON ur.uid = u.uid LEFT JOIN role r ON r.rid = ur.rid GROUP BY r.rid ORDER BY r.name in /home/mustafau/pdt_workspace/drupal/includes/database.pgsql.inc on line 144.