在释放锁之前，如何确保在PostgreSQL中完成了写操作?

I have a function on a Django model that calculates a value from a PostgreSQL 9.5 database and, based on the result, determines whether to add data in another row. The function must know the value before adding the row, and future values of the calculation will be dependent on the new row.I have a function on a Django model that calcul