ankitsultana commented on code in PR #12538:
URL: https://github.com/apache/pinot/pull/12538#discussion_r1509906166
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pinot-segment-local/src/main/java/org/apache/pinot/segment/local/utils/HashUtils.java:
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@@ -36,6 +40,35 @@ public static byte[] hashMD5(byte[] bytes) {
return Hashing.md5().hashBytes(bytes).asBytes();
}
+ /**
+ * For use-cases where the primary-key is set to columns that are guaranteed
to be type-4 UUIDs, this hash-function
+ * will reduce the number of bytes required from 36 to 16 for each UUID,
without losing any precision. This leverages
+ * the fact that a type-4 UUID is essentially a 16-byte value.
+ */
+ public static byte[] hashUUIDv4(byte[] bytes) {
+ if (bytes.length % 36 != 0) {
+ return bytes;
+ }
+ byte[] resultBytes = new byte[(bytes.length / 36) * 16];
+ ByteBuffer byteBuffer =
ByteBuffer.wrap(resultBytes).order(ByteOrder.BIG_ENDIAN);
+ for (int chunk = 0; chunk < bytes.length; chunk += 36) {
+ byte[] tempBytes = new byte[36];
+ System.arraycopy(bytes, chunk, tempBytes, 0, tempBytes.length);
+ UUID uuid;
+ try {
+ uuid = UUID.fromString(new String(tempBytes, StandardCharsets.UTF_8));
+ } catch (Exception e) {
+ // In case of failures, make the hash no-op.
+ return bytes;
Review Comment:
self-review: is it safe to return the input as is? Ideally we should create
a copy.
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