This PR changes Raft Log Entry encoding from JSON to Protobuf. Furthermore, larger Raft commands (which can result from batching SQL statements, or individually long SQL statements) are compressed before encoding.
This primary reason for this change is to reduce IO load since that is one of the largest performance bottlenecks. It will also reduce internode traffic.
Legacy JSON-encoded commands are still handled by this code, so this change is backwards-compatible with previous releases in the v5 series.
If now supports an array of strings, as before, and also supports arrays
of arrays, where each inner array contains a statement, and parameters
for binding to that statement.
This change allows the read request to specify the maximum time the node
receiving the request may have last heard from the cluster leader. It
only applies to a read consistency selection of None.
A non-voting node doesn't participate in Raft consensus, but does
subscribe to the committed log entries originating with the leader.
This means a non-voting node keeps up-to-date with the state machine,
without impacting write-latency. These non-voting nodes can provide
read scalability for the cluster.
With this change the cluster metadata (arbitrary key-value data associated with each node) is now broadcast across the cluster using the standard consensus mechanism. Specifically the use case for this metadata is to allow all nodes know the HTTP API address of all other nodes, for the purpose of redirecting requests to the leader.
This change removed the need for multiplexing two logical connections
over the single Raft TCP connection, which greatly simplifies the
networking code generally.
Original PR https://github.com/rqlite/rqlite/pull/434
The -http-ca-cert and -node-ca-cert options allow the user to specify
trusted X.509 root CA certificates as an alternative to the
-http-no-verify and -node-no-verify options. This behavior is analogous
to the rqlite client -ca-cert option.
Philip O'Toole
Zac Medico