Hi, On 19 September 2011 11:14, Craig James <craig_ja...@emolecules.com> wrote: > DBsig for a hash-collision chain is always the bitwise OR of every record in > that hash-collision chain. When you add a record to the hash table, you do > a bitwise OR of its signature into the existing DBsig. If you delete a > record, you erase DBsig and rebuild it by recomputing the signatures of each > record in the hash-collision chain and ORing them together again.
Sound like a Bloom filter [1] to me. BTW, Does Postgres use Bloom filter anywhere? [1] http://en.wikipedia.org/wiki/Bloom_filter -- Ondrej Ivanic (ondrej.iva...@gmail.com) -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
