Re: Deprecating RULES

On 10/17/2012 07:25 PM, Tom Lane wrote:

>
> I'm fairly annoyed by the entire tenor of this conversation, because
> the people who are hollering the loudest seem to be people who have
> never actually touched any of the rules code, but nonetheless seem
> prepared to tell those of us who have what to spend our time on.

+1

I too have been quite annoyed.

>
> Now having said that, I would definitely like to see rules in their
> current form go away eventually.  But not without a substitute.
> Triggers are not a complete replacement, and no amount of wishful
> thinking makes them so.
>
> Perhaps it would be more profitable to try to identify the pain points
> that make people so eager to get rid of rules, and then see if we could
> alleviate them.  One big problem I know about offhand is the
> multiple-evaluation risk, which seems at least in principle fixable.
> What others are there?
>
>             


Yeah. That's by far the best approach. It has the merit of being 
positive rather than just taking something away that people do use, even 
if it's only a relatively small number of users.

The biggest pain people have mentioned is that they don't work with 
COPY.  I am in fact about to start working on a project which will 
probably alleviate that pain point. I'm not going to say much more, and 
I would not have said anything right now except that there is this 
sudden rush to deprecate rules, or announce a future removal of the 
feature. However, I hope to have a proposal to put to the community by 
about the end of November.

On that point, it's also worth noting that FDWs provide a nice 
workaround, instead of doing a straight
    COPY TO mytable FROM myfile

you set up the source as a foreign table using file_fdw or my 
file_text_array_fdw, and then do
    INSERT INTO mytable    SELECT ...    FROM my_foreign_table;

Maybe this too would be worth mentioning in the docs, maybe in the rules 
section with an xref from the copy section.

So, please, hold off for little bit. I don't mind putting warnings in 
the docs, but I'd really rather we waited on any announcement of a 
future possible deprecation, or log warnings that using rules will cause 
zombies to eat your brainz.

cheers

andrew