Re: Is passing a list as a bound variable safe from SQL injection?

On Wed, Oct 2, 2013 at 12:17 PM, Daniele Varrazzo <
daniele(dot)varrazzo(at)gmail(dot)com> wrote:

> What other approach? Not using IN: the IN operator is converted to "=
> any(array)" by the postgres parser:
>
> =# explain select * from x where id in (1,2,3,4,5);
> QUERY PLAN
> ------------------------------------------------------------
> Seq Scan on x (cost=0.00..6.58 rows=5 width=51)
> Filter: (id = ANY ('{1,2,3,4,5}'::integer[]))
>
> It is true that this can be very inefficient for long lists, I've
> experimented it myself several times, but it's not something you can
> change at driver level: creating a temp table to join on can be faster
> even for not very long lists.
>
>
> -- Daniele
>

This is the approach (and it does involve very long lists):

http://www.datadoghq.com/2013/08/100x-faster-postgres-performance-by-changing-1-line/

Instead of writing = any(array[1,2,3,4]), they wrote = any(values (1), (2),
(3), (4), )

and somehow that works more quickly.

Would it be possible to make a python list subclass that converts itself to
"values ( ... )" rather than to "array[ ... ]"? I imagine that this might
be useful for these gigantic lists.

Matt

--
W. Matthew Wilson
matt(at)tplus1(dot)com
http://tplus1.com