Dan Hecht has posted comments on this change. ( http://gerrit.cloudera.org:8080/7438 )
Change subject: IMPALA-4939, IMPALA-4940: Decimal V2 multiplication ...................................................................... Patch Set 6: (7 comments) mostly just some questions. http://gerrit.cloudera.org:8080/#/c/7438/6//COMMIT_MSG Commit Message: http://gerrit.cloudera.org:8080/#/c/7438/6//COMMIT_MSG@67 PS6, Line 67: after: 126.17s is it always the case that this regression is in cases that would have (incorrectly) returned null before this change? http://gerrit.cloudera.org:8080/#/c/7438/6/be/src/runtime/decimal-value.inline.h File be/src/runtime/decimal-value.inline.h: http://gerrit.cloudera.org:8080/#/c/7438/6/be/src/runtime/decimal-value.inline.h@a253 PS6, Line 253: great to see that go away http://gerrit.cloudera.org:8080/#/c/7438/6/be/src/runtime/decimal-value.inline.h@245 PS6, Line 245: overflow instead of saying "we will overflow", I think "we indicate overflow" or "return overflow" or something like that. I was trying to figure out where the overflow occurs until I continued reading. http://gerrit.cloudera.org:8080/#/c/7438/6/be/src/runtime/decimal-value.inline.h@244 PS6, Line 244: If delta scale is 0, we need to do a more precise check if converting to 256 bits : // is necessary I don't understand that comment, given that line 240-241 says the first check was conservative. http://gerrit.cloudera.org:8080/#/c/7438/6/be/src/runtime/decimal-value.inline.h@273 PS6, Line 273: // with a delta_scale 39 does not fit into int128. so normally the (38,38) * (38,38) case would be handled in the needs_int256 case, is that right? is this case just when the values are so small that they turn into 0? http://gerrit.cloudera.org:8080/#/c/7438/6/be/src/runtime/decimal-value.inline.h@284 PS6, Line 284: nit: let's eliminate this blank line (and maybe others. this function already barely fits on one screen which is important for readability. http://gerrit.cloudera.org:8080/#/c/7438/6/be/src/util/bit-util.h File be/src/util/bit-util.h: http://gerrit.cloudera.org:8080/#/c/7438/6/be/src/util/bit-util.h@292 PS6, Line 292: __int128 shifted = v >> 64; : if (shifted > 0) { given that 'v' is unsigned, won't the shift be unsigned, meaning 'shifted' will always get zeros in the top 64, meaning shifted is always >= 0? oh, so is this really just checking "shifted != 0"? If so, that seems clearer, especially since the else-clause only makes sense for 0, not for negative. -- To view, visit http://gerrit.cloudera.org:8080/7438 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: I37ad6232d7953bd75c18dc86e665b2b501a1ebe1 Gerrit-Change-Number: 7438 Gerrit-PatchSet: 6 Gerrit-Owner: Taras Bobrovytsky <tbobrovyt...@cloudera.com> Gerrit-Reviewer: Dan Hecht <dhe...@cloudera.com> Gerrit-Reviewer: Jim Apple <jbapple-imp...@apache.org> Gerrit-Reviewer: Michael Ho <k...@cloudera.com> Gerrit-Reviewer: Taras Bobrovytsky <tbobrovyt...@cloudera.com> Gerrit-Reviewer: Tim Armstrong <tarmstr...@cloudera.com> Gerrit-Reviewer: Zach Amsden <zams...@cloudera.com> Gerrit-Comment-Date: Fri, 29 Sep 2017 23:23:02 +0000 Gerrit-HasComments: Yes
