[1.6.x] Fixed #22458 -- Added a note about MySQL utf8_unicode_ci collation

Thanks tobami at gmail.com for the report.

Backport of 11ac50b18e from master

1 files changed, 9 insertions, 0 deletions

diff --git a/docs/ref/databases.txt b/docs/ref/databases.txt
index ef2e1b8583..883417bea0 100644
--- a/docs/ref/databases.txt
+++ b/docs/ref/databases.txt
@@ -360,6 +360,15 @@ table (usually called ``django_session``) and the
 
 .. _fixed in MySQLdb 1.2.2: http://sourceforge.net/tracker/index.php?func=detail&aid=1495765&group_id=22307&atid=374932
 
+Please note that according to `MySQL Unicode Character Sets`_, comparisons for
+the ``utf8_general_ci`` collation are faster, but slightly less correct, than
+comparisons for ``utf8_unicode_ci``. If this is acceptable for your application,
+you should use ``utf8_general_ci`` because it is faster. If this is not acceptable
+(for example, if you require German dictionary order), use ``utf8_unicode_ci``
+because it is more accurate.
+
+.. _MySQL Unicode Character Sets: http://dev.mysql.com/doc/refman/5.7/en/charset-unicode-sets.html
+
 Connecting to the database
 --------------------------