diff --git a/src/knnresult.jl b/src/knnresult.jl
new file mode 100644
index 0000000..d282531
--- /dev/null
+++ b/src/knnresult.jl
@@ -0,0 +1,174 @@
+# This file is a part of SimilaritySearch.jl
+using Intersections
+
+export maxlength, maxlength, getpair, getdist, getid, initialstate, idview, distview, reuse!
+
+export KnnResult
+
+"""
+    KnnResult(ksearch::Integer)
+
+Creates a priority queue with fixed capacity (`ksearch`) representing a knn result set.
+It starts with zero items and grows with [`push!(res, id, dist)`](@ref) calls until `ksearch`
+size is reached. After this only the smallest items based on distance are preserved.
+"""
+struct KnnResult # <: AbstractVector{Tuple{IdType,DistType}}
+    id::Vector{Int32}
+    dist::Vector{Float32}
+    k::Int  # number of neighbors
+end
+
+function KnnResult(k::Integer)
+    @assert k > 0
+    res = KnnResult(Vector{Int32}(undef, 0), Vector{Float32}(undef, 0), k)
+    sizehint!(res.id, k)
+    sizehint!(res.dist, k)
+    res
+end
+
+"""
+    _shifted_fixorder!(res, shift=0)
+
+Sorts the result in place; the possible element out of order is on the last entry always.
+It implements a kind of insertion sort that it is efficient due to the expected
+distribution of the items being inserted (it is expected just a few elements smaller than the current ones)
+"""
+function _shifted_fixorder!(res, shift=0)
+    sp = shift + 1
+    pos = N = lastindex(res.id)
+    id = res.id
+    dist = res.dist
+    id_, dist_ = res.id[end], res.dist[end]
+    
+    #pos = doublingsearch(dist, dist_, sp, N)
+    #pos = binarysearch(dist, dist_, sp, N)
+    #if N > 16
+    #    pos = doublingsearchrev(dist, dist_, sp, N)::Int
+    #else
+        @inbounds while pos > sp && dist_ < dist[pos-1]
+            pos -= 1
+        end
+    #end
+
+    @inbounds if pos < N
+        while N > pos
+            id[N] = id[N-1]
+            dist[N] = dist[N-1]
+            N -= 1
+        end
+
+        dist[N] = dist_
+        id[N] = id_
+    end
+
+    nothing
+end
+
+
+"""
+    push!(res::KnnResult, item::Pair)
+    push!(res::KnnResult, id::Integer, dist::Real)
+
+Appends an item into the result set
+"""
+@inline function Base.push!(res::KnnResult, id::Integer, dist::Real)
+    if length(res) < maxlength(res)
+        k = res.k
+        push!(res.id, id)
+        push!(res.dist, dist)
+    
+        _shifted_fixorder!(res)
+        return true
+    end
+
+    dist >= last(res.dist) && return false
+
+    @inbounds res.id[end], res.dist[end] = id, dist
+    _shifted_fixorder!(res)
+    #_shifted_fixorder!(res.shift, res.id, res.dist)
+    true
+end
+
+#@inline Base.push!(res::KnnResult, id::Integer, dist::Real) = push!(res, convert(Int32, id), convert(Float32, dist))
+@inline Base.push!(res::KnnResult, p::Pair) = push!(res, p.first, p.second)
+
+"""
+    popfirst!(p::KnnResult)
+
+Removes and returns the nearest neeighboor pair from the pool, an O(length(p.pool)) operation
+"""
+@inline function Base.popfirst!(res::KnnResult)
+    popfirst!(res.id) => popfirst!(res.dist)
+end
+
+"""
+    pop!(res::KnnResult)
+
+Removes and returns the last item in the pool, it is an O(1) operation
+"""
+@inline function Base.pop!(res::KnnResult)
+    pop!(res.id) => pop!(res.dist)
+end
+
+"""
+    maxlength(res::KnnResult)
+
+The maximum allowed cardinality (the k of knn)
+"""
+@inline maxlength(res::KnnResult) = res.k
+@inline Base.length(res::KnnResult) = length(res.id)
+
+"""
+    reuse!(res::KnnResult)
+    reuse!(res::KnnResult, k::Integer)
+
+Returns a result set and a new initial state; reuse the memory buffers
+"""
+@inline function reuse!(res::KnnResult, k::Integer=res.k)
+    @assert k > 0
+    empty!(res.id)
+    empty!(res.dist)
+    if k > res.k
+        sizehint!(res.id, k)
+        sizehint!(res.dist, k)
+    end
+    KnnResult(res.id, res.dist, k)
+end
+
+"""
+    getindex(res::KnnResult, i)
+
+Access the i-th item in `res`
+"""
+@inline function getpair(res::KnnResult, i)
+    @inbounds res.id[i] => res.dist[i]
+end
+
+@inline getid(res::KnnResult, i) = @inbounds res.id[i]
+@inline getdist(res::KnnResult, i) = @inbounds res.dist[i]
+
+@inline Base.last(res::KnnResult) = last(res.id) => last(res.dist)
+@inline Base.first(res::KnnResult) = @inbounds res.id[1] => res.dist[1]
+@inline Base.maximum(res::KnnResult) = last(res.dist)
+@inline Base.minimum(res::KnnResult) = @inbounds res.dist[1]
+@inline Base.argmax(res::KnnResult) = last(res.id)
+@inline Base.argmin(res::KnnResult) = @inbounds res.id[1]
+
+@inline idview(res::KnnResult) = res.id
+@inline distview(res::KnnResult) = res.dist
+
+@inline Base.eachindex(res::KnnResult) = 1:length(res)
+Base.eltype(res::KnnResult) = Pair{Int32,Float32}
+
+##### iterator interface
+### KnnResult
+"""
+    Base.iterate(res::KnnResult, state::Int=1)
+
+Support for iteration
+"""
+function Base.iterate(res::KnnResult, i::Int=1)
+    n = length(res)
+    (n == 0 || i > n) && return nothing
+    @inbounds res.id[i] => res.dist[i], i+1
+end
\ No newline at end of file
diff --git a/src/knnresultshift.jl b/src/knnresultshift.jl
new file mode 100644
index 0000000..708435b
--- /dev/null
+++ b/src/knnresultshift.jl
@@ -0,0 +1,198 @@
+# This file is a part of SimilaritySearch.jl
+struct KnnResultState
+    shift::Int
+end
+
+export initialstate, KnnResultShift
+
+"""
+    KnnResultShift(ksearch::Integer)
+
+Creates a priority queue with fixed capacity (`ksearch`) representing a knn result set.
+It starts with zero items and grows with [`push!(res, id, dist)`](@ref) calls until `ksearch`
+size is reached. After this only the smallest items based on distance are preserved.
+"""
+struct KnnResultShift
+    id::Vector{Int32}
+    dist::Vector{Float32}
+    k::Int # number of neighbors
+end
+
+function KnnResultShift(k::Integer)
+    @assert k > 0
+    res = KnnResultShift(Vector{Int32}(undef, 0), Vector{Float32}(undef, 0), k)
+    sizehint!(res.id, k)
+    sizehint!(res.dist, k)
+    res
+end
+
+function initialstate(::KnnResultShift)
+    KnnResultState(0)
+end
+
+"""
+    push!(res::KnnResultShift, item::Pair)
+    push!(res::KnnResultShift, id::Integer, dist::Real)
+
+Appends an item into the result set
+"""
+@inline function Base.push!(res::KnnResultShift, st::KnnResultState, id::Integer, dist::Real)
+    if length(res, st) < maxlength(res)
+        k = res.k
+        if length(res.id) >= 2k-1
+            compact!(res, st, 1)
+            st = KnnResultState(0)
+            @inbounds res.id[end], res.dist[end] = id, dist
+        else
+            push!(res.id, id)
+            push!(res.dist, dist)
+        end
+    
+        _shifted_fixorder!(res, st.shift)
+        #_shifted_fixorder!(res.shift, res.id, res.dist)
+        return st
+    end
+
+    dist >= last(res.dist) && return st
+
+    @inbounds res.id[end], res.dist[end] = id, dist
+    _shifted_fixorder!(res, st.shift)
+    #_shifted_fixorder!(res.shift, res.id, res.dist)
+    st
+end
+
+#@inline Base.push!(res::KnnResultShift, st::KnnResultState, id::Integer, dist::Real) = push!(res, st, convert(Int32, id), convert(Float32, dist))
+@inline Base.push!(res::KnnResultShift, st::KnnResultState, p::Pair) = push!(res, st, p.first, p.second)
+
+function compact!(res::KnnResultShift, st::KnnResultState, resize_extra)
+    shift = st.shift
+    if shift > 0
+        n = length(res, st)
+        j = shift
+        @inbounds for i in 1:n
+            j += 1
+            res.id[i] = res.id[j]
+            res.dist[i] = res.dist[j]
+        end
+
+        resize!(res.id, n+resize_extra)
+        resize!(res.dist, n+resize_extra)
+    end
+
+    res
+end
+
+"""
+    popfirst!(p::KnnResultShift, st::KnnResultState)
+
+Removes and returns the nearest neeighboor pair from the pool, an O(length(p.pool)) operation
+"""
+@inline function Base.popfirst!(res::KnnResultShift, st::KnnResultState)
+    p = argmin(res, st) => minimum(res, st)
+    res.id[1] = 0  # mark as deleted
+    p, KnnResultState(st.shift+1)
+end
+
+"""
+    pop!(res::KnnResultShift, st::KnnResultState)
+
+Removes and returns the last item in the pool, it is an O(1) operation
+"""
+@inline function Base.pop!(res::KnnResultShift, st::KnnResultState)
+    pop!(res.id) => pop!(res.dist), st
+end
+
+"""
+    maxlength(res::KnnResultShift)
+
+The maximum allowed cardinality (the k of knn)
+"""
+@inline maxlength(res::KnnResultShift) = res.k
+@inline Base.length(res::KnnResultShift, st::KnnResultState) = length(res.id) - st.shift
+
+function Base.length(res::KnnResultShift)
+    i = 1
+    n = length(res.id)
+    while i < n && res.id[i] == 0
+        i += 1
+    end
+
+    n - i + 1
+end
+
+"""
+    reuse!(res::KnnResultShift)
+    reuse!(res::KnnResultShift, k::Integer)
+
+Returns a result set and a new initial state; reuse the memory buffers
+"""
+@inline function reuse!(res::KnnResultShift, k::Integer=res.k)
+    @assert k > 0
+    empty!(res.id)
+    empty!(res.dist)
+    if k > res.k
+        sizehint!(res.id, k)
+        sizehint!(res.dist, k)
+    end
+    KnnResultShift(res.id, res.dist, k)
+end
+
+"""
+    getindex(res::KnnResultShift, st::KnnResultState, i)
+
+Access the i-th item in `res`
+"""
+@inline function getpair(res::KnnResultShift, st::KnnResultState, i)
+    i += st.shift
+    @inbounds res.id[i] => res.dist[i]
+end
+
+@inline getid(res::KnnResultShift, st::KnnResultState, i) = @inbounds res.id[i+st.shift]
+@inline getdist(res::KnnResultShift, st::KnnResultState, i) = @inbounds res.dist[i+st.shift]
+
+@inline Base.last(res::KnnResultShift, st::KnnResultState) = last(res.id) => last(res.dist)
+@inline Base.first(res::KnnResultShift, st::KnnResultState) = res.id[st.shift+1] => res.dist[st.shift+1]
+@inline Base.maximum(res::KnnResultShift, st::KnnResultState) = last(res.dist)
+@inline Base.minimum(res::KnnResultShift, st::KnnResultState) = res.dist[1+st.shift]
+@inline Base.argmax(res::KnnResultShift, st::KnnResultState) = last(res.id)
+@inline Base.argmin(res::KnnResultShift, st::KnnResultState) = res.id[1+st.shift]
+
+Base.maximum(res::KnnResultShift) = last(res.dist)
+Base.argmax(res::KnnResultShift) = last(res.id)
+Base.minimum(res::KnnResultShift) = res.dist[_find_start_position(res)]
+Base.argmin(res::KnnResultShift) = res.id[_find_start_position(res)]
+
+@inline idview(res::KnnResultShift, st::KnnResultState) = @view res.id[st.shift+1:end]
+@inline distview(res::KnnResultShift, st::KnnResultState) = @view res.dist[st.shift+1:end]
+
+@inline Base.eachindex(res::KnnResultShift, st::KnnResultState) = 1:length(res, st)
+Base.eltype(res::KnnResultShift) = Pair{Int32,Float32}
+
+##### iterator interface
+### KnnResultShift
+"""
+    Base.iterate(res::KnnResultShift, state::Int=1)
+
+Support for iteration
+"""
+@inline function _find_start_position(res::KnnResultShift)
+    i = 1
+    id = res.id
+    n = length(id)
+    @inbounds while i <= n && id[i] == 0
+        i += 1
+    end
+    
+    i
+end
+
+function Base.iterate(res::KnnResultShift, i::Int=-1)
+    n = length(res.id)
+    n == 0 && return nothing
+    if i == -1
+        i = _find_start_position(res)
+    end
+
+    i > n && return nothing
+    @inbounds res.id[i] => res.dist[i], i+1
+end
\ No newline at end of file