Adar Dembo has posted comments on this change. ( http://gerrit.cloudera.org:8080/14644 )
Change subject: [cfile] Improve the hash function of pair<DataType, EncodingType> ...................................................................... Patch Set 2: (2 comments) http://gerrit.cloudera.org:8080/#/c/14644/2//COMMIT_MSG Commit Message: http://gerrit.cloudera.org:8080/#/c/14644/2//COMMIT_MSG@13 PS2, Line 13: For example, the hash values of <UINT32=4, BIT_SHUFFLE=6> : and <INT32=5, PLAIN_ENCODING=1> are both equal to `100101` > May be I'm missing something obvious, but I'm afraid I don't see collision. The '^' in this case is XOR, not pow(x,y). (4+31) ^ 6: 37 (5+31) ^ 1: 37 It's a little weird to use base10 representation though; the base2 representation is 100101 as Lingbin wrote. http://gerrit.cloudera.org:8080/#/c/14644/2/src/kudu/cfile/type_encodings.cc File src/kudu/cfile/type_encodings.cc: http://gerrit.cloudera.org:8080/#/c/14644/2/src/kudu/cfile/type_encodings.cc@208 PS2, Line 208: return (pair.first << 5) + pair.second; gutil/hash/hash.h defines a hash functor for pairs; maybe use that? -- To view, visit http://gerrit.cloudera.org:8080/14644 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: kudu Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: Id141c51147ae674b9bee3016026a0b91cb76b5aa Gerrit-Change-Number: 14644 Gerrit-PatchSet: 2 Gerrit-Owner: Anonymous Coward <[email protected]> Gerrit-Reviewer: Adar Dembo <[email protected]> Gerrit-Reviewer: Bankim Bhavsar <[email protected]> Gerrit-Reviewer: Kudu Jenkins (120) Gerrit-Comment-Date: Thu, 07 Nov 2019 00:50:13 +0000 Gerrit-HasComments: Yes
