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ASF GitHub Bot commented on DRILL-4618: --------------------------------------- Github user chunhui-shi commented on the issue: https://github.com/apache/drill/pull/509 @StevenMPhillips Hi Steven, is this fix addressing your concern now? Thanks. > random numbers generator function broken > ---------------------------------------- > > Key: DRILL-4618 > URL: https://issues.apache.org/jira/browse/DRILL-4618 > Project: Apache Drill > Issue Type: Bug > Reporter: Chunhui Shi > Assignee: Chunhui Shi > > File this JIRA based on the the bug description from Ted's email and > discussion in dev mail list for record purpose: > I am trying to generate some random numbers. I have a large base file (foo) > this is what I get: > 0: jdbc:drill:> select floor(1000*random()) as x, floor(1000*random()) as > y, floor(1000*rand()) as z from (select * from maprfs.tdunning.foo) a limit > 20; > +--------+--------+--------+ > | x | y | z | > +--------+--------+--------+ > | 556.0 | 556.0 | 618.0 | > | 564.0 | 564.0 | 618.0 | > | 129.0 | 129.0 | 618.0 | > | 48.0 | 48.0 | 618.0 | > | 696.0 | 696.0 | 618.0 | > | 642.0 | 642.0 | 618.0 | > | 535.0 | 535.0 | 618.0 | > | 440.0 | 440.0 | 618.0 | > | 894.0 | 894.0 | 618.0 | > | 24.0 | 24.0 | 618.0 | > | 508.0 | 508.0 | 618.0 | > | 28.0 | 28.0 | 618.0 | > | 816.0 | 816.0 | 618.0 | > | 717.0 | 717.0 | 618.0 | > | 334.0 | 334.0 | 618.0 | > | 978.0 | 978.0 | 618.0 | > | 646.0 | 646.0 | 618.0 | > | 787.0 | 787.0 | 618.0 | > | 260.0 | 260.0 | 618.0 | > | 711.0 | 711.0 | 618.0 | > +--------+--------+--------+ > On this page, https://drill.apache.org/docs/math-and-trig/, the rand > function is described and random() is not. But it appears that rand() > delivers a constant instead (although a different constant each time the > query is run) and it appears that random() delivers the same value when > used multiple times in each returned value. > This seems very, very wrong. > The fault does not seem to be related to my querying a table: > 0: jdbc:drill:> select rand(), random(), random() from (values (1),(2),(3)) > x; > +---------------------+-----------------------+-----------------------+ > | EXPR$0 | EXPR$1 | EXPR$2 | > +---------------------+-----------------------+-----------------------+ > | 0.1347749257216052 | 0.36724556209765014 | 0.36724556209765014 | > | 0.1347749257216052 | 0.006087161689924625 | 0.006087161689924625 | > | 0.1347749257216052 | 0.09417099142512142 | 0.09417099142512142 | > +---------------------+-----------------------+-----------------------+ > For reference, postgres doesn't have rand() and does the right thing with > random(). -- This message was sent by Atlassian JIRA (v6.3.4#6332)