[IMPALA-6168] Different result range of rand/random built-in function

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Duplicate
• Affects Version/s: Impala 2.10.0
• Component/s: Backend
• Labels: correctness newbie
• Epic Color: ghx-label-2
• Assignee: Adam Tamas
• Reporter: Jin Chul Kim
• Created: 07/Nov/17 09:05
• Updated: 30/Mar/20 15:58
• Resolved: 30/Mar/20 14:14

Description

I am not sure this is a bug because it might be intended behavior. Please close this if it is not a bug.

When I was re-implementing rand at IMPALA-5754, I realized some DBMSes(e.g. Postgres, MySQL and Vertica) adopt the following range: "0 <= result < 1". By the way, Impala's range of the current implementation is "0 <= result <= 1" and document also says "Returns a random value between 0 and 1".

Would you let me know why the difference comes from? Please explain if it is intended behavior.

Issue Links

• is related to: IMPALA-5754 rand() algorithm is very non-random