I use MySQL 5.7 and the following query (derived from drupal 7):

select distinct node.nid, node.title, node.changed, users_node.name   from node    left join users users_node on node.uid = users_node.uid   order by node.nid desc   limit 4; 

In some servers the results look like this which seems correct:

+-----+----------------------------+------------+------+ | nid | title                      | changed    | name | +-----+----------------------------+------------+------+ | 521 | ...                        | 1501674634 | xx   | | 520 | ...                        | 1501674634 | xx   | | 519 | ...                        | 1501674634 | xx   | | 517 | ...                        | 1501674634 | xx   | +-----+----------------------------+------------+------+ 

But in some other servers I get the opposite nid order from what I expect:

+-----+----------------------------+------------+------+ | nid | title                      | changed    | name | +-----+----------------------------+------------+------+ |   1 | ...                        | 1501674634 | xx   | |   2 | ...                        | 1501674634 | xx   | |   3 | ...                        | 1501674634 | xx   | |   4 | ...                        | 1501674634 | xx   | +-----+----------------------------+------------+------+ 

How can this be explained? Is it the case that the final order of the results cannot be guaranteed when using the distinct keyword?