[GitHub] [incubator-doris] xinyiZzz opened a new pull request #5226: [Bug] Fix row_number and group by have inconsistent partition results for (0.0, -0.0)

[GitBox <gi...@apache.org>]

xinyiZzz opened a new pull request #5226:
URL: https://github.com/apache/incubator-doris/pull/5226


   ## Proposed changes
   
   ####problem analysis
   The essence of the problem is negative zero (-0.0) and positive zero (+0.0) compared with different results. C++ defaults -0 == 0 return truem. To unify the eq relationship of -0 and 0 in Doris, modified to -0 == 0 return false.
   
   ####Change location
   1. Compare whether two double values ​​are equal in BinaryPredicate
   2. Overloaded operator== operator in DoubleVal
   
   ####The remaining problems
   1. When order by is still considered equal to 0.0 and -0.0, the order of 0.0 and -0.0 in the result is random
   2. Floating point arithmetic in C++ is often IEEE-754. This norm defines two different representations for the value zero: positive zero and negative zero. It is also defined that those two representations must compare equals. So A better way is to unify the eq relationship of -0 and 0 as true.
   
   ref: https://stackoverflow.com/questions/45795397
   ref: https://www.johndcook.com/blog/2010/06/15/why-computers-have-signed-zero/
   
   ## Types of changes
   
   - [x] Bugfix (non-breaking change which fixes an issue)
   
   ## Checklist
   
   - [x] I have create an issue on (Fix #5225), and have described the bug/feature there in detail
   - [x] Compiling and unit tests pass locally with my changes


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[GitHub] [incubator-doris] morningman merged pull request #5226: [Bug] Fix row_number and group by have inconsistent partition results for (0.0, -0.0)

[GitBox <gi...@apache.org>]

morningman merged pull request #5226:
URL: https://github.com/apache/incubator-doris/pull/5226


   


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