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Benedict commented on CASSANDRA-6809: ------------------------------------- bq. Good catch, the number of segments needed can depend on the sync period, thus this does need to be exposed. Done, as a non-published option in cassandra.yaml for now What's stopping us ensuring there are always enough (or treating this as a hard limit rather than an actual number)? Seems like ensuring we have the number of buffers in flight + 1 should be enough to reach a steady state rapidly without overcommitting memory... > Compressed Commit Log > --------------------- > > Key: CASSANDRA-6809 > URL: https://issues.apache.org/jira/browse/CASSANDRA-6809 > Project: Cassandra > Issue Type: Improvement > Reporter: Benedict > Assignee: Branimir Lambov > Priority: Minor > Labels: docs-impacting, performance > Fix For: 3.0 > > Attachments: ComitLogStress.java, logtest.txt > > > It seems an unnecessary oversight that we don't compress the commit log. > Doing so should improve throughput, but some care will need to be taken to > ensure we use as much of a segment as possible. I propose decoupling the > writing of the records from the segments. Basically write into a (queue of) > DirectByteBuffer, and have the sync thread compress, say, ~64K chunks every X > MB written to the CL (where X is ordinarily CLS size), and then pack as many > of the compressed chunks into a CLS as possible. -- This message was sent by Atlassian JIRA (v6.3.4#6332)