Re: Re: custom hash-based COUNT(DISTINCT) aggregate - unexpectedly high memory consumption

Hi Tomas,


>> Consider the aspects associated with open addressing.Open addressing
>> can quickly lead to growth in the main table.Also, chaining is a much
>> cleaner way of collision resolution,IMHO.
>
> What do you mean by "growth in the main table"?

Sorry, I should have been more verbose.

AFAIK, Open addressing can be slower with a load factor approaching 1
as compared to chaining. Also, I feel that implementation of open
addressing can be more complicated as we have to deal with deletes
etc.

I feel we can redesign our current chaining mechanism to have skip
lists instead of singly linked lists. I experimented with it sometime
back and I feel that it gives a stable performance with higher loads.

Regards,

Atri



-- 
Regards,

Atri
l'apprenant