Re: [PR] Try using Murmurhash 3 for bloom filters [lucene]

["jpountz (via GitHub)" <gi...@apache.org>]

jpountz commented on code in PR #12868:
URL: https://github.com/apache/lucene/pull/12868#discussion_r1794974762


##########
lucene/codecs/src/java/org/apache/lucene/codecs/bloom/FuzzySet.java:
##########
@@ -150,9 +149,10 @@ private FuzzySet(FixedBitSet filter, int bloomSize, int hashCount) {
    * @return NO or MAYBE
    */
   public ContainsResult contains(BytesRef value) {
-    long hash = hashFunction.hash(value);
-    int msb = (int) (hash >>> Integer.SIZE);
-    int lsb = (int) hash;
+    long[] hash = StringHelper.murmurhash3_x64_128(value);
+
+    int msb = (((int) hash[0] >>> Integer.SIZE) >>> 1) + (((int) hash[1] >>> Integer.SIZE) >>> 1);
+    int lsb = ((int) hash[0] >>> 1) + ((int) hash[1] >>> 1);

Review Comment:
   Can you make this simpler? E.g. `long msb = hash[0]; long lsb = hash[1];` and later `int bloomPos = ((int) (lsb + i * msb)) & bloomSize;`?



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