In a future major version, we will be introducing a soft limit on the
number of shards in a cluster based on the number of nodes in the
cluster. This limit will be configurable, and checked on operations
which create or open shards and issue a warning if the operation would
take the cluster over the limit.
There is an option to enable strict enforcement of the limit, which
turns the warnings into errors. In a future release, the option will be
removed and strict enforcement will be the default (and only) behavior.
The shard preference _primary, _replica and its variants were useful
for the asynchronous replication. However, with the current impl, they
are no longer useful and should be removed.
Closes#26335
We use `:` for cross-cluster search (eg `cluster:index`), therefore, we should
not allow the ambiguity when allowing cluster or index names.
Relates to #23892
Gordon Brown
Lisa Cawley
Nhat
Yannick Welsch
Lee Hinman