Re: functions: stable/volatile

On Mon, 20 Nov 2006, Rafal Pietrak wrote:

> The most obvious construct I'd use is:
>         UPDATE my_table set filed=newvalue WHERE
>                  my_function(input)=my_table.selector_field;
> but it's useless, since the function would have been be evaluated for
> every row of the table.

-- Not tested

create function update_my_table(newvalue, input)
    returns void
    volatile
    language plpgsql
as $$
declare
    selector selector_field_type;
begin
    selector := my_function(input);
    update my_table set filed=newvalue
        where my_table.selector_field=selector;
end;
$$;

-- and then

select update_my_table(newvalue, input);

-- Not tested.

Regards
Tometzky
--
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