How to create recurrence schedule event?

Hi,

I am trying to port sybase codes to posgresql. I have looked into the postgresql documentation
but couldn't find good information on how to create an equivalent recurrence event
which similar to the sybase codes below.

Can some one please help?

sybase codes:

create event PURGE_ORDER schedule
start time '00:00:00' every 30 minutes
on ( 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday','Saturday', 'Sunday' )

handler begin

declare @value varchar(128);
call cleanup_order();
end;

Thanks,
QT