Simon Riggs wrote:
> On Tue, 2007-04-17 at 17:16 -0400, Tom Lane wrote:
>> A recent discussion led me to the idea that FK triggers are fired
>> unnecessarily during an UPDATE if the foreign-key column(s) contain
>> any NULLs, because ri_KeysEqual() treats two nulls as unequal,
>> and therefore we conclude the row has changed when it has not.
>
> FK trigger *can be optimised away* is true. No need to have a discussion
> about whether NULL == NULL, but the critical test is: if I overwrote it,
> would you be able to tell? The answer is No, so away it goes.
The test should perhaps be named "unchanged" rather than "equal".
-- Richard Huxton Archonet Ltd