[Kde-pim] Akonadi encoding woes

[Milian Wolff]

Heyho,

I've debugged the encoding problems in Akonadi and found that it is mainly due 
to a Qt bug I just reported together with a testcase. Essentially, Qt does 
double encoding on BINARY fields.

http://bugreports.qt.nokia.com/browse/QTBUG-11963

Ok, now what the hell are BINARY fields and why do we need them? Well, mysql is 
"wonderful":

mysql> select 'ä' = 'a', 'Ä ' = 'a';
+------------+-------------+
| 'ä' = 'a' | 'Ä ' = 'a' |
+------------+-------------+
|          1 |           1 |
+------------+-------------+

Coming up with even stranger examples is left as an exercise for the bored 
reader.

Anyhow, this is the "equals" operator on non-binary fields. If you would select 
and compare against a field marked binary, you'd have expected behavior. But 
well, binary fields show the double encoding. What to do? I just found the 
'LIKE BINARY' operator:

mysql> select 'ä' LIKE BINARY 'a', 'Ä ' LIKE BINARY 'a';
+----------------------+-----------------------+
| 'ä' LIKE BINARY 'a' | 'Ä ' LIKE BINARY 'a' |
+----------------------+-----------------------+
|                    0 |                     0 |
+----------------------+-----------------------+

Thankfully Akonadi uses a QueryBuilder, so either me or volker will "fix" == 
workaround this awful behavior by doing two things:

- remove all BINARY marks from fields in the table schema
- make the QueryBuilder replace LIKE and = with LIKE BINARY for mysql.

Bye
-- 
Milian Wolff
mail at milianw.de
http://milianw.de
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