Parallel replicas always skip unavailable ones

[nikitamikhaylov]

Changelog category (leave one):

• Improvement

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

When parallel replicas are enabled they will always skip unavailable servers (the behavior is controlled by the setting skip_unavailable_shards, enabled by default and can be only disabled). This closes: #48565

[robot-clickhouse-ci-2]

This is an automated comment for commit 3d21bb0 with description of existing statuses. It's updated for the latest CI running
The full report is available here
The overall status of the commit is 🟡 pending

Check name	Description	Status
CI running	A meta-check that indicates the running CI. Normally, it's in success or pending state. The failed status indicates some problems with the PR	🟡 pending
Mergeable Check	Checks if all other necessary checks are successful	🟢 success
Push to Dockerhub	The check for building and pushing the CI related docker images to docker hub	🟢 success
security/snyk (ClickHouse)	There's no description for the check yet, please add it to tests/ci/ci_config.py:CHECK_DESCRIPTIONS	🟢 success

[qoega]

Why shards but not replicas in the name?

[alexey-milovidov]

Because parallel replicas are dynamic shards.

But we also should take care about consistency with the implementation of the same behavior in the s3Cluster and urlCluster table functions.

[nikitamikhaylov]

Looks like it already works for *Cluster table functions

ClickHouse/src/Storages/IStorageCluster.cpp

Line 137 in 688f23b

new_settings.skip_unavailable_shards = true;

[alexey-milovidov]

Yes, see #46314
My point is that the implementation has to be consistent.