Last week in scylla.git master (issue #93; 2021-08-29)

[Avi Kivity]

This short report brings to light some interesting commits to scylla.git master from the last week. Commits in the f98cb9650..998dadf479 range are covered.

There were 135 non-merge commits from 17 authors in that period. Some notable commits:

The cache abstraction that is used to implemented the prepared statement cache has been made more robust, eliminating cases where the entry was expired prematurely.

It is now required to enable Raft with a configuration item (experimental: raft). This lets the implementation mature without requiring backwards compatibility efforts.

When streaming data from a Time Window Compaction Strategy table, Scylla segregates the data into the correct time window to follow the compaction strategy rules. This however causes a large number of sstables to be created, overloading the node in extreme cases. We now postpone data segregation to a later phase, offstrategy compaction, which happens after the number of sstables has been reduced.

A scalability problem on very large NUMA nodes has been fixed. The cause was a global variable that was written frequently (but never read) causing nearby frequently-read global variables to be removed from the CPU cache.

See you in the next issue of last week in scylla.git master!