How to only insert rows that do not violate a specific constraint

PostgreSQL offers an alternative to raising an exception upon a unique key violation: ON CONFLICT ON CONSTRAINT

INSERT INTO sales.sales_history 
SELECT * from sales.sales_history_p201801 
ON CONFLICT ON CONSTRAINT uc_sh1 DO NOTHING;

Comes in as a handy way of transfering rows from an old table to a partially populated new table. Duplicate rows will simply be ignored.

Documentation for PostgreSQL 11 can be found here.