[GitHub] [arrow-rs] XinyuZeng commented on a diff in pull request #3119: parquet bloom filter part III: add sbbf writer, remove `bloom` default feature, add reader properties

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

XinyuZeng commented on code in PR #3119:
URL: https://github.com/apache/arrow-rs/pull/3119#discussion_r1110973057


##########
parquet/src/bloom_filter/mod.rs:
##########
@@ -113,7 +116,48 @@ fn read_bloom_filter_header_and_length(
     ))
 }
 
+const BITSET_MIN_LENGTH: usize = 32;
+const BITSET_MAX_LENGTH: usize = 128 * 1024 * 1024;
+
+#[inline]
+fn optimal_num_of_bytes(num_bytes: usize) -> usize {
+    let num_bytes = num_bytes.min(BITSET_MAX_LENGTH);
+    let num_bytes = num_bytes.max(BITSET_MIN_LENGTH);
+    num_bytes.next_power_of_two()
+}
+
+// see http://algo2.iti.kit.edu/documents/cacheefficientbloomfilters-jea.pdf

Review Comment:
   @Jimexist Wondering why here we round num_bytes to next power of two? parquet-mr just rounds to (k * BITS_PER_BLOCK)



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