Luca Looz <luca.looz92@gmail.com> writes: > 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. > Is this an expected behavior? Why it happens?
Yes, see comment in RI_FKey_fk_upd_check_required:
* If the original row was inserted by our own transaction, we * must fire the trigger whether or not the keys are equal. This * is because our UPDATE will invalidate the INSERT so that the * INSERT RI trigger will not do anything; so we had better do the * UPDATE check. (We could skip this if we knew the INSERT * trigger already fired, but there is no easy way to know that.)
Although this is talking about the BEGIN; INSERT; UPDATE; COMMIT case, the code has no way to tell that apart from BEGIN; UPDATE; UPDATE; COMMIT.