On Sat, 14 Sep 2019 10:00:18 -0500, Ron <ronljohnsonjr@xxxxxxxxx> wrote: >On 9/14/19 9:54 AM, Tom Lane wrote: >[snip >> The only mention of this feature in 38.1 "Overview of Trigger Behavior" >> is >> >> UPDATE triggers*can* moreover be set to fire only if certain columns >> are mentioned in the SET clause of the UPDATE statement. >> >> which seems to me to be plenty specific enough --- it is carefully >> *not* saying that the trigger will fire if the column changes value. >> The CREATE TRIGGER man page never says that, either. > >Given that the UPDATE "*can* ... be set to fire only if certain columns are >mentioned in the SET clause of the UPDATE statement", it logically follows >that the default behavior is something else (for example, if the field value >changes for whatever reason. But the default could be "any column mentioned", not necessarily any value changed. George
