always_fetch_merged_part
If true, this replica never merges parts and always downloads merged parts from other replicas. Possible values:- true, false
always_fetch_mutated_part
If true, this replica never executesMUTATE_PART replication log entries
(regular mutations such as ALTER TABLE ... UPDATE/DELETE) and always
downloads the resulting mutated parts from other replicas.
At least one replica must have this setting disabled; otherwise mutations
cannot finish.
This setting does not affect patch parts created by lightweight updates:
they are still applied locally when parts are merged. Enable
always_fetch_merged_part as well to also offload merges (including the
application of patch parts) to other replicas.
Because this replica does not execute mutations, and mutation failure
status is local to each replica, a synchronous wait on this replica
cannot observe mutation failures that happen on the replicas executing
the mutation. Therefore synchronous mutations (mutations_sync = 1
or 2) and synchronous ALTER queries that mutate data
(alter_sync = 1 or 2) are rejected on such a replica with a
SUPPORT_IS_DISABLED error instead of a wait that would hang if the
mutation fails. Use mutations_sync = 0 (alter_sync = 0), or issue
these queries on a replica that executes mutations.
Possible values:
- true, false