对于 Postgres 中已插入的记录，我可以在插入 function 之前手动触发吗？

Question

I am using PostgreSQL 14.5

I have a beneficiaries table where people are registered and I have BEFORE INSERT trigger function that generates a unique ID based on their location (if Paris - PAR-001, if London - LON-004, etc) and it works.

But the problem is, lots of records are inserted before writing this function, and since the function is triggered BEFORE INSERT I can't have the ID s for them.

I have seen the documentation and didn't find how to trigger the function for previous records

Can I manually trigger this function for all records once or any other solution?

Answer 1

Add an additional trigger like this:

CREATE TRIGGER temp BEFORE UPDATE ON tab
   FOR EACH ROW WHEN (OLD.id IS NULL)
   EXECUTE FUNCTION your_trigger_func();

The trigger function is the one you use in your BEFORE INSERT trigger. Then update all these rows:

UPDATE tab SET id = id WHERE id IS NULL;

You can drop the trigger when you are done.

You can perform the update in batches and run VACUUM on the table in between, to avoid bloat by a single massive update.