Under use_compact_format_in_distributed_parts_names=1 and
internal_replication=true the server encodes all replicas for the
directory name for async INSERT into Distributed, and the directory name
looks like:
shard1_replica1,shard1_replica2,shard3_replica3
This is required for creating connections (to specific replicas only),
but in case of internal_replication=true, this can be avoided, since
this path will always includes all replicas.
This patch replaces all replicas with "_all_replicas" marker.
Note, that initial problem was that this path may overflow the NAME_MAX
if you will have more then 15 replicas, and the server will fail to
create the directory.
Also note, that changed directory name should not be a problem, since:
- empty directories will be removed since #16729
- and replicas encoded in the directory name is also supported anyway.
