UPDATE column without FK fires other FK triggers constraint check

[Luca Looz <luca.looz92@xxxxxxxxx>]

I was analyzing an update function and i have noticed "Trigger for constraint" entries for foreign keys that i wasn't using or referring.

After some tests it seems that this happens when the same row is covered by more than 1 update in the same transaction even without any change.

Here is a dbfiddle example:

http://dbfiddle.uk/?rdbms=postgres_9.6&fiddle=368289a7338031b8a7b7a90f0fd25d7c

Is this an expected behavior? Why it happens?

I have initially asked this on dba stackexchange:

https://dba.stackexchange.com/questions/180012/