Function mz_adapter::coord::sequencer::inner::check_log_reads

pub(super) fn check_log_reads(
    catalog: &Catalog,
    cluster: &Cluster,
    source_ids: &BTreeSet<GlobalId>,
    target_replica: &mut Option<ReplicaId>,
    vars: &SessionVars,
) -> Result<impl IntoIterator<Item = AdapterNotice>, AdapterError>

Checks whether we should emit diagnostic information associated with reading per-replica sources.

If an unrecoverable error is found (today: an untargeted read on a cluster with a non-1 number of replicas), return that. Otherwise, return a list of associated notices (today: we always emit exactly one notice if there are any per-replica log dependencies and if emit_introspection_query_notice is set, and none otherwise.)