2010/12/24 Florian Pflug <f...@phlo.org>: > On Dec23, 2010, at 20:39 , Tomas Vondra wrote: > >> I guess we could use the highest possible value (equal to the number >> of tuples) - according to wiki you need about 10 bits per element >> with 1% error, i.e. about 10MB of memory for each million of >> elements. > > Drat. I had expected these number to come out quite a bit lower than > that, at least for a higher error target. But even with 10% false > positive rate, it's still 4.5MB per 1e6 elements. Still too much to > assume the filter will always fit into memory, I fear :-(
I have the impression that both of you are forgetting that there are 8 bits in a byte. 10 bits per element = 1.25MB per milion elements. Nicolas -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
