Re: Query generates infinite loop

Hi

st 20. 4. 2022 v 18:42 odesílatel Richard Wesley <richard(at)duckdblabs(dot)com>
napsal:

> Hi All -
>
> I was implementing the infinity time constants in DuckDB when I ran into
> an infinite loop. It seems that PG has the same problem for the same reason
> (adding an interval to an infinite timestamp produces the same timestamp,
> so the increment operation never goes anywhere.) Here is the query:
>
> 1.
>
> select COUNT(*) FROM generate_series('-infinity'::TIMESTAMP, 'epoch'::TIMESTAMP, INTERVAL '1 DAY');
>
>
>
> This seems like a DoS great attack, so we are disallowing infinities as
> bounds for both table and scalar series generation. As an upper bound, it
> eventually gives an error, so it seems there is not much utility anyway.
>

There are more ways to achieve the same effect. The protection is safe
setting of temp_file_limit

2022-04-20 09:59:54) postgres=# set temp_file_limit to '1MB';
SET
(2022-04-20 18:51:48) postgres=# select COUNT(*)
FROM generate_series('-infinity'::TIMESTAMP, 'epoch'::TIMESTAMP, INTERVAL
'1 DAY');
ERROR: temporary file size exceeds temp_file_limit (1024kB)
(2022-04-20 18:51:50) postgres=#

Regards

Pavel

>
> Met vriendelijke groet, best regards, mit freundlichen Grüßen,
>
> *Richard Wesley*
> Group-By Therapist
> richard(at)duckdblabs(dot)com
>
>
>
>
>