ObjVersions   versionsHistogram `msg:"vh"`
	AllTierStats  *allTierStats     `msg:"ats,omitempty"`
	Compacted     bool              `msg:"c"`
}

// allTierStats is a collection of per-tier stats across all configured remote
// tiers.
type allTierStats struct {
	Tiers map[string]tierStats `msg:"ts"`
}

func newAllTierStats() *allTierStats {
	return &allTierStats{
		Tiers: make(map[string]tierStats),
	}
}