mirror of
https://git.postgresql.org/git/postgresql.git
synced 2024-08-21 16:03:24 +02:00
Adds a BRIN opclass using a Bloom filter to summarize the range. Indexes using the new opclasses allow only equality queries (similar to hash indexes), but that works fine for data like UUID, MAC addresses etc. for which range queries are not very common. This also means the indexes work for data that is not well correlated to physical location within the table, or perhaps even entirely random (which is a common issue with existing BRIN minmax opclasses). It's possible to specify opclass parameters with the usual Bloom filter parameters, i.e. the desired false-positive rate and the expected number of distinct values per page range. CREATE TABLE t (a int); CREATE INDEX ON t USING brin (a int4_bloom_ops(false_positive_rate = 0.05, n_distinct_per_range = 100)); The opclasses do not operate on the indexed values directly, but compute a 32-bit hash first, and the Bloom filter is built on the hash value. Collisions should not be a huge issue though, as the number of distinct values in a page ranges is usually fairly small. Bump catversion, due to various catalog changes. Author: Tomas Vondra <tomas.vondra@postgresql.org> Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org> Reviewed-by: Alexander Korotkov <aekorotkov@gmail.com> Reviewed-by: Sokolov Yura <y.sokolov@postgrespro.ru> Reviewed-by: Nico Williams <nico@cryptonector.com> Reviewed-by: John Naylor <john.naylor@enterprisedb.com> Discussion: https://postgr.es/m/c1138ead-7668-f0e1-0638-c3be3237e812@2ndquadrant.com Discussion: https://postgr.es/m/5d78b774-7e9c-c94e-12cf-fef51cc89b1a%402ndquadrant.com |
||
---|---|---|
.. | ||
src | ||
KNOWN_BUGS | ||
Makefile | ||
MISSING_FEATURES | ||
TODO |