Unexpected -0.0

[bajinsheng]

Describe the problem

Some mathematical calculations return negative zeros, which seems unexpected.

To Reproduce

testdb=> select 0 * -69.5;
 ?column? 
----------
     -0.0
(1 row)

Expected behavior
The result should be 0.0 without negative symbol.

Environment:

• CockroachDB version [7625d9f]
• Server OS: [Linux/Ubuntu]
• Client app [psql]

Jira issue: CRDB-49710

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[mw5h]

This is likely a floating point conversion issue, since IEEE floats actually have a -0.0. Interestingly, it doesn't happen if we execute via prepared statement.

demo@127.0.0.1:26257/demoapp/defaultdb> prepare stmt as select 0 * $1;                                                                                                                                                   
PREPARE

Time: 0ms total (execution 0ms / network 0ms)

demo@127.0.0.1:26257/demoapp/defaultdb> execute stmt(-69.5);                                                                                                                                                             
  ?column?
------------
         0
(1 row)

Time: 1ms total (execution 0ms / network 0ms)

demo@127.0.0.1:26257/demoapp/defaultdb> select 0 * -69;                                                                                                                                                                  
  ?column?
------------
         0
(1 row)

Time: 1ms total (execution 0ms / network 0ms)

Thank you for the report, I agree that this is confusing!