Everything works as expected on my development machine, but when deploying to quality assurance environment, tests are failing because MariaDB is padding the result set with extra precision zeros after a decimal.

For example, when I run this query:

    SELECT GREATEST(  '2016-04-14 15:06:30', NOW() )

On dev, running Ubuntu 14.04.4 LTS (Trusty Tahr) mysql Ver 14.14 Distrib 5.5.47, for debian-linux-gnu (x86_64) using readline 6.3, I get this expected result:

> 2016-04-18 09:07:42

On test, running Red Hat Enterprise Linux Server 7.2 (Maipo) mysql  Ver 15.1 Distrib 5.5.44-MariaDB, for Linux (x86_64) using readline 5.1, I get this **un**expected result:

> 2016-04-18 09:07:42.000000

I don't see anything in the [`GREATEST()` documentation](https://dev.mysql.com/doc/refman/5.7/en/comparison-operators.html#function_greatest) that would explain this behavior, so I think it must be a server configuration setting in `my.cnf` but I couldn't find anything in online search results.

Even more curiously, when running the following queries, I get the same **unpadded** results on *both* machines:

    SELECT GREATEST(  '2016-04-14 15:06:30', '2016-04-14 16:06:30' )

> 2016-04-14 16:06:30

    SELECT GREATEST(  NOW(), NOW() )

> 2016-04-18 09:24:22

    SELECT GREATEST(  5, 10 )

> 10


**Why is MariaDB `GREATEST()` padding/appending my result set with zeros on timestamp comparison with `NOW()`?**