Taras Bobrovytsky has posted comments on this change. ( http://gerrit.cloudera.org:8080/6023 )
Change subject: IMPALA-4848: Add WIDTH_BUCKET() function ...................................................................... Patch Set 7: (1 comment) http://gerrit.cloudera.org:8080/#/c/6023/7/be/src/exprs/math-functions-ir.cc File be/src/exprs/math-functions-ir.cc: http://gerrit.cloudera.org:8080/#/c/6023/7/be/src/exprs/math-functions-ir.cc@516 PS7, Line 516: int256_t x = ConvertToInt256(buckets.value()) * ConvertToInt256(width_size.value()); > Sure, that's true. I don't think that this function is meant to be used tha This idea may give a nice performance boost (if it works) because all the heavy lifting (such as dividing and maybe converting to int256) is done once at the beginning when we are constructing the array. The array will contain values that have the same precision and scale as the input expression so all we have to do is O(log(number of buckets)) comparisons of expr to array elements in case of binary search. Or O(number of buckets) comparisons if number of buckets is small. If number of buckets is very large, we can fall back to the current implementation. (we can have 2 versions WidthBucketImpl such as WidthBucketImplSmall WidthBucketImplLarge) -- To view, visit http://gerrit.cloudera.org:8080/6023 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: I081bc916b1bef7b929ca161a9aade3b54c6b858f Gerrit-Change-Number: 6023 Gerrit-PatchSet: 7 Gerrit-Owner: anujphadke <apha...@cloudera.com> Gerrit-Reviewer: Alex Behm <alex.b...@cloudera.com> Gerrit-Reviewer: Michael Brown <mi...@cloudera.com> Gerrit-Reviewer: Taras Bobrovytsky <tbobrovyt...@cloudera.com> Gerrit-Reviewer: anujphadke <apha...@cloudera.com> Gerrit-Comment-Date: Tue, 10 Oct 2017 00:49:40 +0000 Gerrit-HasComments: Yes
