Summary:
Admin Search fails on some searches with default mysql mode only_full_group_by (mysql 5.7.5+)
Detailed Description:
Some searches in Admin Search were yielding no results when they should have.
Error log showed it was the new default mysql mode of only_full_group_by
MySQL 5.7.5 and later implements detection of functional dependence. If the
ONLY_FULL_GROUP_BY SQL mode is enabled (which it is by default), MySQL rejects
queries for which the select list, HAVING condition, or ORDER BY list refer to
nonaggregated columns that are neither named in the GROUP BY clause nor are
functionally dependent on them. (Before 5.7.5, MySQL does not detect functional
dependency and ONLY_FULL_GROUP_BY is not enabled by default. For a description
of pre-5.7.5 behavior, see the MySQL 5.6 Reference Manual.)
Workaround is to change the mysql mode to exclude only_full_group_by, but for
many users this would require the host to make a change they're unwilling/unable
to make.
(note: some modules, including FEU/MAMS, also have this issue)