Re: Change GUC hashtable to use simplehash?

Hi,

On 2023-11-21 16:42:55 +0700, John Naylor wrote:
> I get a noticeable regression in 0002, though, and I think I see why:
>
> guc_name_hash(const char *name)
> {
> - uint32 result = 0;
> + const unsigned char *bytes = (const unsigned char *)name;
> + int blen = strlen(name);
>
> The strlen call required for hashbytes() is not free. The lack of
> mixing in the (probably inlined after 0001) previous hash function can
> remedied directly, as in the attached:

I doubt this is a good hashfunction. For short strings, sure, but after
that... I don't think it makes sense to reduce the internal state of a hash
function to something this small.

Greetings,

Andres Freund