diff --git a/src/MetidaBase.jl b/src/MetidaBase.jl
index d0710e4..76ef6da 100644
--- a/src/MetidaBase.jl
+++ b/src/MetidaBase.jl
@@ -6,7 +6,7 @@ module MetidaBase
 
     using StatsModels, Tables
     import Tables: istable, columnaccess, columns, getcolumn, columnnames
-    import Base: getindex, length
+    import Base: getindex, length, ht_keyindex
 
     include("abstracttype.jl")
     include("types.jl")
diff --git a/src/types.jl b/src/types.jl
index 7b6b147..99e9080 100644
--- a/src/types.jl
+++ b/src/types.jl
@@ -17,8 +17,7 @@ Tables.getcolumn(t, nm::Symbol) = t.table[nm]
 
 Tables.columnnames(t::MetidaTable) = collect(keys(t.table))
 
-
-# MetidaFreq.jl
+# All
 
 struct DataSet{T <: AbstractData}
     data::Vector{T}
@@ -32,6 +31,32 @@ function Base.length(ds::DataSet)
     length(ds.data)
 end
 
+function getindormiss(d, i)
+    ind = ht_keyindex(d, i)
+    if ind > 0 return d.vals[ind]  else return missing  end
+end
+function islessdict(a::Dict{A1,A2}, b::Dict{B1,B2}, k::Union{AbstractVector, Set}) where A1 where A2 where B1 where B2
+    l = length(k)
+    av = Vector{Union{Missing, A2}}(undef, l)
+    bv = Vector{Union{Missing, B2}}(undef, l)
+    @inbounds for i = 1:l
+        av[i] = getindormiss(a, k[i])
+        bv[i] = getindormiss(b, k[i])
+    end
+    isless(av, bv)
+end
+function islessdict(a::Dict, b::Dict, k)
+    isless(getindormiss(a, k), getindormiss(b, k))
+end
+function Base.sort!(a::DataSet{T}, k; alg::Base.Algorithm = QuickSort, lt=nothing, by=nothing, rev::Bool=false, order::Base.Ordering = Base.Forward) where T <: AbstractIdData
+    if isnothing(by) by = x -> x.id end
+    if isnothing(lt) lt = (x, y) -> islessdict(x, y, k) end
+    sort!(a.data;  alg = alg, lt = lt, by = by, rev = rev, order = order)
+    a
+end
+
+# MetidaFreq.jl
+
 struct Proportion <: AbstractData
     x::Int
     n::Int