TWCS is a proposed improvement on DTCS. The motivations for TWCS are explained at:
https://issues.apache.org/jira/browse/CASSANDRA-9666
And:
http://www.slideshare.net/JeffJirsa1/cassandra-summit-2015-real-world-dtcs-for-operators
Checkout the repo:
git clone https://github.com/jeffjirsa/twcs/Switch to the right version (for newest 2.1 release, for example):
git checkout origin cassandra-2.1 Build the jar:
mvn compile
mvn packageThe resulting jar will be placed in target/, copy it to the classpath of your cassandra server.
Use the WITH compaction= directive to set the compaction strategy. By default, TWCS creates 1 Day buckets and assumes MICROSECOND resolution.
Use compaction_window_unit of MINUTES, HOURS, or DAYS and compaction_window_size as an integer to group sstables into buckets of a fixed size that matches your use case.
Use timestamp_resolution to let the compaction strategy know which time unit to use.
To create 3 minute buckets of microsecond resolution (for example, for data with very short TTL), you would use:
CREATE TABLE twcs (
id int,
value int,
PRIMARY KEY ((id))
) WITH compaction= {
'compaction_window_unit': 'MINUTES',
'compaction_window_size': '3',
'class':'com.jeffjirsa.cassandra.db.compaction.TimeWindowCompactionStrategy'
};You should target fewer than 50 buckets per table based on your TTL. A TTL of 90 days may want 3 day buckets, where a TTL of 2 hours may want 5 minute buckets.
This repository ( https://github.com/jeffjirsa/twcs ) will be used for standalone TWCS code (simple jar to drop into lib/). For practical purposes, in this repository the compaction strategy is com.jeffjirsa.cassandra.db.compaction.TimeWindowCompactionStrategy
TWCS is also available as a C* fork (in the hopes that patches are accepted upstream):
2.1: https://github.com/jeffjirsa/cassandra/tree/twcs-2.1
2.2: https://github.com/jeffjirsa/cassandra/tree/twcs-2.2
Trunk / 3.0: https://github.com/jeffjirsa/cassandra/tree/twcs
In the full fork, the compaction strategy is: org.apache.cassandra.db.compaction.TimeWindowCompactionStrategy
TWCS is provided under the Apache License, V2: http://www.apache.org/licenses/LICENSE-2.0