On 07/23/2015 12:25 PM, Adrian Klaver wrote:
> On 07/23/2015 11:15 AM, Rob Sargent wrote:
>> On 07/23/2015 12:09 PM, Adrian Klaver wrote:
>>> On 07/23/2015 04:57 AM, Tim Smith wrote:
>>>> Andrew,
>>>>
>>>> From the manual:
>>>>
>>>> It is important to realize that a rule is really a command
>>>> transformation mechanism, or command macro. The transformation happens
>>>> before the execution of the command starts. If you actually want an
>>>> operation that fires independently for each physical row, you probably
>>>> want to use a trigger, not a rule
>>>>
>>>>
>>>> Thus, I should not have to use a trigger for TRUNCATE because the
>>>> "each
>>>> row" concept does not apply. Plus it makes perfect sense to
>>>> want to
>>>> transform the truncate command and transform into ignore
>>>>
>>>
>>> Just in case it has not been made obvious yet, rules are silently
>>> deprecated. They still exist because views depend on them, but it is
>>> generally considered best practices to not use them outside that
>>> realm. So if you want the rule behavior to change for TRUNCATE(if that
>>> is even possible) you are fighting an uphill battle. You may pursue
>>> that fight of course, but I would think you will get a quicker return
>>> on your time if you just forget about using a RULE and stick to a
>>> TRIGGER instead.
>>>
>> Or change to using delete instead of truncate?
>>
>
> Well Tim has an ON DELETE rule:
>
> http://www.postgresql.org/message-id/CA+HuS5G2bZYYOGTJrw+VosjUPO298swxuU=JOrFAv54UT7vniQ@mail.gmail.com
>
>
> His expectation was that would also catch a TRUNCATE based on this:
>
> "... It has the same effect as an unqualified DELETE on each table, ..."
>
> from here:
>
> http://www.postgresql.org/docs/9.4/interactive/sql-truncate.html
>
> It was then explained that while TRUNCATE had the same end result as
> 'DELETE FROM some_table' it was actually a separate command and
> action. Tim wants to catch a TRUNCATE and turn it into an ignore.
>
>
I'm suggesting OP might find changing truncate statements to deletes
(without a where clause) a simpler solution. Something has to change.