Parallel Insert and Delete operation

Hi All,

Please clarify me the following example.

I have 2 tables

Table1 - ( it has one primary key and few columns )
Table2 - ( it has one primary key and few columns. It has one foreign key, which refers table1 primary key ).

I have 2 operations, which are written in pl/pgsql procedure.

Operation1() - Inserts the records to table2 at every hour basis.
Operation2() - Delete the records from Table 1 and Table2 based on the primary key.

What if both operations are running at the time for the same primary key.

what I have to take care to run these two operations perfectly without creating inconsistency in database.

Thanks & Regards,
Ramkumar