diff --git a/test/data.table.timings.jl b/test/data.table.timings.jl
new file mode 100644
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+++ b/test/data.table.timings.jl
@@ -0,0 +1,86 @@
+# Julia benchmarks from R's data.table
+# https://github.com/Rdatatable/data.table/wiki/Benchmarks-:-Grouping
+
+using DataFrames, DataFramesMeta
+using NullableArrays
+
+N=10_000_000; K=100
+srand(1)
+
+# Array version
+
+DA = DataFrame(
+  id1 = P(rand([symbol(string("id", i)) for i=1:K], N)),          # large groups (char)
+  id2 = P(rand([symbol(string("id", i)) for i=1:K], N)),          # large groups (char)
+  id3 = P(rand([symbol(string("id", i)) for i=1:Int(N/K)], N)),   # small groups (char)
+  id4 = P(rand(1:K, N)),                          # large groups (int)
+  id5 = P(rand(1:K, N)),                          # large groups (int)
+  id6 = P(rand(1:Int(N/K), N)),                   # small groups (int)
+  v1 =  P(rand(1:5, N)),                          # int in range [1,5]
+  v2 =  P(rand(1:5, N)),                          # int in range [1,5]
+  v3 =  P(rand(N))                                # numeric e.g. 23.5749
+);
+
+# PooledDataArray version
+
+DPDA = DataFrame(
+  id1 = PooledDataArray(rand([symbol(string("id", i)) for i=1:K], N)),     # large groups (char)
+  id2 = PooledDataArray(rand([symbol(string("id", i)) for i=1:K], N)),     # large groups (char)
+  id3 = PooledDataArray(rand([symbol(string("id", i)) for i=1:Int(N/K)], N)),   # small groups (char)
+  id4 = PooledDataArray(rand(1:K, N)),                          # large groups (int)
+  id5 = PooledDataArray(rand(1:K, N)),                          # large groups (int)
+  id6 = PooledDataArray(rand(1:Int(N/K), N)),                   # small groups (int)
+  v1 =  P(rand(1:5, N)),                          # int in range [1,5]
+  v2 =  P(rand(1:5, N)),                          # int in range [1,5]
+  v3 =  P(rand(N))                                # numeric e.g. 23.5749
+);
+
+# DataArray version
+
+DDA = DataFrame(
+  id1 = (rand([symbol(string("id", i)) for i=1:K], N)),          # large groups (char)
+  id2 = (rand([symbol(string("id", i)) for i=1:K], N)),          # large groups (char)
+  id3 = (rand([symbol(string("id", i)) for i=1:Int(N/K)], N)),   # small groups (char)
+  id4 = (rand(1:K, N)),                          # large groups (int)
+  id5 = (rand(1:K, N)),                          # large groups (int)
+  id6 = (rand(1:Int(N/K), N)),                   # small groups (int)
+  v1 =  (rand(1:5, N)),                          # int in range [1,5]
+  v2 =  (rand(1:5, N)),                          # int in range [1,5]
+  v3 =  (rand(N))                                # numeric e.g. 23.5749
+);
+
+# NullableArray version
+
+DNA = DataFrame(
+  id1 = P(NullableArray(rand([symbol(string("id", i)) for i=1:K], N))),          # large groups (char)
+  id2 = P(NullableArray(rand([symbol(string("id", i)) for i=1:K], N))),          # large groups (char)
+  id3 = P(NullableArray(rand([symbol(string("id", i)) for i=1:Int(N/K)], N))),   # small groups (char)
+  id4 = P(NullableArray(rand(1:K, N))),                          # large groups (int)
+  id5 = P(NullableArray(rand(1:K, N))),                          # large groups (int)
+  id6 = P(NullableArray(rand(1:Int(N/K), N))),                   # small groups (int)
+  v1 =  P(NullableArray(rand(1:5, N))),                          # int in range [1,5]
+  v2 =  P(NullableArray(rand(1:5, N))),                          # int in range [1,5]
+  v3 =  P(NullableArray(rand(N)))                                # numeric e.g. 23.5749
+);
+
+
+function dt_timings(D)
+    @time @by(D, :id1, sv =sum(:v1));
+    @time @by(D, :id1, sv =sum(:v1));
+    @time @by(D, [:id1, :id2], sv =sum(:v1));
+    @time @by(D, [:id1, :id2], sv =sum(:v1));
+    @time @by(D, :id3, sv = sum(:v1), mv3 = mean(:v3));
+    @time @by(D, :id3, sv = sum(:v1), mv3 = mean(:v3));
+    @time aggregate(D[[4,7:9;]], :id4, mean);
+    @time aggregate(D[[4,7:9;]], :id4, mean);
+    @time aggregate(D[[6,7:9;]], :id6, sum);
+    @time aggregate(D[[6,7:9;]], :id6, sum);
+    return
+end
+
+dt_timings(DA)
+dt_timings(DPDA)
+dt_timings(DNA)
+dt_timings(DDA)
+
+@profile @by(D, :id1, sv =sum(:v1));