How to insert data in custom table in respective company using data entity
Is it limited to data import? Can you confirm that no change should be logged in ITPriceHistory if price changes inside F&O, such as by a user or in code? It would sound strange.
Even if you say that it can't be changed by users and you don't have any code changing the value, it would make sense to do it on table level rather than on a particular way of changing the data. Also, even if there is no code changing the data, someone may add such code tomorrow, therefore depending on it isn't the best approach.
If you insist on doing it in the entity, postLoad() is a bad choice, because that's a method called when reading the data, not when writing it. You should use something like persistEntity().