Meet SPQR 2.1.0

[Denchick]

Hi! Our team has done a lot of work recently. Here are some of the main areas that we have been working on.

REDISTRIBUTE KEY RANGE
Added a new command in addition to the MOVE KEY RANGE. The main difference between them is that REDISTRIBUTE transfers the key range in small portions so as to minimize the downtime for write queries.

Multishard COPY support
We added special settings that allow you to make multishard copies in a non-transactional, non-consistent manner.

Prefer hosts in the same availability zone
We introduced a new term "availability zone" (AZ). We assume that the router has its own availability zone and it would be cool if he was prefer sending read-only queries to the same availability zone to minimize latency.

We still have a lot of room for improvement. The full list of changes can be found in the release notes. Many thanks to @EinKrebs @reshke and @Denchick!

Stay tuned!