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> > However I'm unable to make it at least comparable to chaining. The trick > is that the hash table performs reasonably only until it's ~ 65-70% full, > it gets really slow after that. So to maintain performance comparable to > chaining, I'd have to keep the table below this threshold, effectively > wasting ~30% of memory. I expected that. AFAIK, open addressing gets slow when the load factor approaches 1. I feel this is what is happening here. > > And the topic of this thread was about decreasing the memory consumptions, > so it seems to me open-addressing is not a good match here. I'll try a few > more things but I don't think it's going to fly. > Yeah, I also feel that open addressing isn't the way to go for the problem here. > I've made some significant improvements in the chaining version (in the > master branch), now getting about the memory consumption I've estimated. > I agree, we can hope to reduce the memory consumption by making changes in the current chaining implementation. I would like to look into changing the data structure used for chaining from singly linked list to maybe skip list or something else. Regards, Atri -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
