Re: Triggers on columns

On Mon, 2009-09-07 at 11:20 +0900, Itagaki Takahiro wrote:
> We are discussing how to determine modified columns
> (UPDATE-target vs. changes of actual values), but in the patch
> I used value-based checking. The reasons are:

If you implement a new feature using syntax from the standard, you have
to implement the semantics of the standard. If you don't like the
semantics of the standard, use a different syntax.

> 2. IMHO, almost users don't expect their triggers are not called
> if the actual values are not modified.

Well, as we saw upthread, there can be different valid opinions on this.
But consider the following:

- Statement triggers are called even if the table was not actually
changed in a semantically significant way.

- Row triggers are called even if the row was not actually changed in a
semantically significant way.

Therefore, it cannot be completely unexpected if column triggers are
called even if the column was not actually changed in a semantically
significant way.