Currently, feature service uses `system_keyspace::load_topology_state`
to load information about features from the `system.topology` table.
This function implicitly assumes that it is called after schema
commitlog replay and will correspond to the state of the topology state
machine after some command is applied.
However, feature check happens before the commitlog replay. If some
group 0 command consists of multiple mutations that are not applied
atomically, the `load_topology_state` function may fail to construct a
`service::topology` object based on the table state. Moreover, this
function not only checks `system.topology` but also
`system.cdc_generations_v3` - in the case of the issue, the entry that
was loaded from the this table didn't contain the `num_ranges`
parameter.
In order to fix this, the feature check code now uses
`load_topology_features_state` which only loads enabled and supported
features from `system.topology`. Only this information is really
necessary for the feature check, and it doesn't have any invariants to
check.
Fixes: #14944Closes#14955
* github.com:scylladb/scylladb:
feature_service: don't load whole topology state to check features
system_keyspace: separate loading topology_features from topology
topology_state_machine: extract features-related fields to a struct
untyped_result_set: add missing_column_exception
421a5ad55c