Tom Lane wrote:
> I wrote:
>
>> Andrew Dunstan <andrew@dunslane.net> writes:
>>
>>> It appears on Googling a bit that the erand48() is buggy in that it
>>> requires the seed to have been initialized with srand48() or it will
>>> constantly return 0.0.
>>>
>
>
>> Huh, and that sends us into an infinite loop? I'll take a look at that.
>> Even though it's surely nonrandom, it doesn't seem like pathological
>> behavior of the RNG should wedge us completely.
>>
>
> The answer is that a constant RNG result sends this bit of
> geqo_selection() into a tight loop:
>
> int first,
> second;
>
> first = linear(root, pool->size, bias);
> second = linear(root, pool->size, bias);
>
> if (pool->size > 1)
> {
> while (first == second)
> second = linear(root, pool->size, bias);
> }
>
> Not sure if it's worth trying to do something about that, or exactly
> what we'd do anyway. Even if we hacked this up somehow, a constant RNG
> result would pretty much break GEQO for any useful purpose. So it could
> be argued that having the regression tests fail here is a good thing...
>
>
>
Right. Let's let sleeping dogs lie. I think at most a code comment is
the only action called for.
cheers
andrew