Improve counter disk usage -------------------------- Key: CASSANDRA-2455 URL: https://issues.apache.org/jira/browse/CASSANDRA-2455 Project: Cassandra Issue Type: Improvement Reporter: Stu Hood
Counter values currently use a huge amount of space on disk: {{(header + length + RF * (nodeid + count + clock)) bytes}} or {{(2 + 2 + RF * (16 + 8 + 8)) bytes}} Type specific compression (as on CASSANDRA-2398) is a long term solution to this problem, but we need a short term fix to make a large volume of counters possible. The largest and most redundant part of the counter is the nodeid, which is now 16 bytes per replica. One proposed fix would be keep a per-sstable dictionary of all replica sets, and to assume the replicas are sorted by nodeid in the counter value. This would allow us to encode the replica as a single integer in the counter value, and to use it to look up the replica set in the dictionary. Assuming an integer replica set id, you could allow for 2^32 replica changes with 4 total bytes of overhead in each counter: {{(header + length + replicasetid + RF (count + clock)) bytes}} or {{(2 + 2 + 4 + RF * (8 + 8)) bytes}} -- This message is automatically generated by JIRA. For more information on JIRA, see: http://www.atlassian.com/software/jira