found a performance bug in reductions/impl.

Author: cnuernber

deps.edn

@@ -153,6 +153,11 @@
   :jdk-11
   {:jvm-opts ["--add-opens=java.base/jdk.internal.ref=ALL-UNNAMED"]}
   :jdk-17
+  {:jvm-opts ["--add-modules" "jdk.incubator.foreign,jdk.incubator.vector"
+              "--enable-native-access=ALL-UNNAMED"
+              "--add-opens=java.base/jdk.internal.ref=ALL-UNNAMED"
+              "--add-opens=java.base/sun.nio.ch=ALL-UNNAMED"]}
+  :jdk-21
   {:jvm-opts ["--add-modules" "jdk.incubator.foreign,jdk.incubator.vector"
               "--enable-native-access=ALL-UNNAMED"
               "--add-opens=java.base/jdk.internal.ref=ALL-UNNAMED"

src/tech/v3/dataset/reductions/impl.clj

@@ -47,7 +47,7 @@
                (reify
                  hamf-proto/Reducer
                  (->init-val-fn [r] init-fn)
-                 (->rfn [r] (hamf-rf/double-accumulator
+                 (->rfn [r] (hamf-rf/long-accumulator
                              acc v (.invokePrim rfn acc (.readDouble col v))))
                  hamf-proto/ParallelReducer
                  (->merge-fn [r] merge-fn)))