Both tables use the default bloom_filter_fp_chance of 0.01 ... CREATE TABLE ... ( a int, b int, bucket timestamp, ts timeuuid, c int, ... PRIMARY KEY ((a, b, bucket), ts, c) ) WITH CLUSTERING ORDER BY (ts DESC, monitor ASC) AND bloom_filter_fp_chance = 0.01 AND compaction = {'class': 'org.apache.cassandra.db.compaction.TimeWindowCompactionStrategy', 'compaction_window_size': '1', 'compaction_window_unit': 'DAYS', 'tombstone_threshold': '0.9', 'unchecked_tombstone_compaction': 'false'} AND dclocal_read_repair_chance = 0.0 AND default_time_to_live = 63072000 AND gc_grace_seconds = 10800 ... AND read_repair_chance = 0.0 AND speculative_retry = 'NONE';
CREATE TABLE ... ( c int, b int, bucket timestamp, ts timeuuid, ... PRIMARY KEY ((c, b, bucket), ts) ) WITH CLUSTERING ORDER BY (ts DESC) AND bloom_filter_fp_chance = 0.01 AND compaction = {'class': 'org.apache.cassandra.db.compaction.TimeWindowCompactionStrategy', 'compaction_window_size': '1', 'compaction_window_unit': 'DAYS', 'tombstone_threshold': '0.9', 'unchecked_tombstone_compaction': 'false'} AND dclocal_read_repair_chance = 0.0 AND default_time_to_live = 63072000 AND gc_grace_seconds = 10800 ... AND read_repair_chance = 0.0 AND speculative_retry = 'NONE'; On Wed, Apr 17, 2019 at 12:25 PM Stefan Miklosovic < stefan.mikloso...@instaclustr.com> wrote: > What is your bloom_filter_fp_chance for either table? I guess it is > bigger for the first one, bigger that number is between 0 and 1, less > memory it will use (17 MiB against 54.9 Mib) which means more false > positives you will get. > > On Wed, 17 Apr 2019 at 19:59, Martin Mačura <m.mac...@gmail.com> wrote: > > > > Hi, > > I have a table with poor bloom filter false ratio: > > SSTable count: 1223 > > Space used (live): 726.58 GiB > > Number of partitions (estimate): 8592749 > > Bloom filter false positives: 35796352 > > Bloom filter false ratio: 0.68472 > > Bloom filter space used: 17.82 MiB > > Compacted partition maximum bytes: 386857368 > > > > It's a time series, TWCS compaction, window size 1 day, data partitioned > in daily buckets, TTL 2 years. > > > > I have another table with a similar schema, but it is not affected for > some reason: > > SSTable count: 1114 > > Space used (live): 329.87 GiB > > Number of partitions (estimate): 25460768 > > Bloom filter false positives: 156942 > > Bloom filter false ratio: 0.00010 > > Bloom filter space used: 54.9 MiB > > Compacted partition maximum bytes: 20924300 > > > > Thanks for any advice, > > > > Martin > > --------------------------------------------------------------------- > To unsubscribe, e-mail: user-unsubscr...@cassandra.apache.org > For additional commands, e-mail: user-h...@cassandra.apache.org > >