Re: Dynamically update NEW columns in plpgsql trigger

On Thu, Sep 9, 2010 at 6:34 PM, Nick <nboutelier(at)gmail(dot)com> wrote:
> On Sep 9, 2:21 am, dmit(dot)(dot)(dot)(at)gmail(dot)com (Dmitriy Igrishin) wrote:
>> Hey Nick,
>>
>> You may do it with PL/pgSQL more easily with hstore module.
>> Please, refer tohttp://www.postgresql.org/docs/9.0/static/hstore.html
>> Please, look at the hstore(record) and populate_record(record, hstore)
>> function. Hope this helps.
>>
>> And I think it will be more faster then you solution.
>>
>> Regards,
>> Dmitriy
>>
>> 2010/9/9 Nick <nboutel(dot)(dot)(dot)(at)gmail(dot)com>
>>
>>
>>
>> > I need to dynamically update NEW columns. Ive been inserting the NEW
>> > values into a temp table, updating them, then passing the temp table
>> > values back to NEW (is there a better way?). Ive had success with this
>> > method unless there is a null value...
>>
>> > EXECUTE 'CREATE TEMP TABLE new AS SELECT $1.*' USING NEW;
>> > EXECUTE 'UPDATE new SET ' || dyn_col_name || ' = 1';
>> > EXECUTE 'SELECT * FROM new' INTO NEW;
>> > EXECUTE 'DROP TABLE new';
>>
>> > This last line...
>> > EXECUTE 'SELECT $1.' || dyn_col_name INTO val USING NEW;
>>
>> > gives the ERROR: could not identify column "col_one" in record data
>> > type.
>>
>> > However RAISE EXCEPTION '%',NEW.col_one;
>> > returns "1" correctly.
>>
>> > If col_one does does not start out as a null value, then everything
>> > works. Why does the passing from temp table back to NEW lose the USING
>> > functionality?
>>
>> > --
>> > Sent via pgsql-general mailing list (pgsql-gene(dot)(dot)(dot)(at)postgresql(dot)org)
>> > To make changes to your subscription:
>> >http://www.postgresql.org/mailpref/pgsql-general- Hide quoted text -
>>
>> - Show quoted text -
>
> Thanks Dmitriy,
>
> Im guessing that hstore(record) is not compatible with 8.4.4? I get an
> error "cannot cast type record to hstore".

nope...9.0. your temp table approach is pretty horrible though --
i'd consider testing 9.0 (likely out in couple weeks) asap, or
consider another pl. the hstore approach is better though...

merlin