Last week in scylla.git master (issue #75; 2021-04-25)

[Avi Kivity]

This short report brings to light some interesting commits to scylla.git master from the last week. Commits in the dbd0b9a3ef..f7e00e781c21 range are covered.

There were 66 non-merge commits from 13 authors in that period. Some notable commits:

There is a new internal keyspace, "system_distributed_everywhere", which is used to propagate internal information that needs higher consistency and bandwidth than gossip. The first user will be Change Data Capture internal data.

The redis protocol server relied on code that was copy-pasted from the cql transport server. The two implementations are now unified into a generic tcp server.

Alternator, Scylla's implementation of a DynamoDB compatible API, has had a few fixes for equality predicates.

The underlying json parser used by alternator, rapidjson, has been hardened against out-of-memory errors.

Reshape is a process that takes place when Scylla needs to incorporate new sstables, such as from repair. It has now reduced write amplification for Time Window Compaction Strategy tables.

The scylla_setup script now supports disabling the NVMe write-back cache on disks that allow it. This is useful to reduce latency on Google Cloud Platform local disks. The machine images built using scylla-machine-image will do this automatically.

The sstable parser will avoid large allocations, reducing latency spikes.

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