--- a/CHANGES.txt	Sat Apr 06 20:37:45 2024 -0400
+++ b/CHANGES.txt	Sat Apr 06 22:47:25 2024 -0400
@@ -16,6 +16,12 @@
 
 Fixed:
 
+- issue2551282 - MySQL utf8mb4 issues and
+  issue2551115 - Use utf8mb4 as a default for MySQL instead of utf8
+  The default database type and collations have been set to:
+  utf8mb4, utf8mb4_unicode_ci and utf8mb4_0900_bin. They are (sadly)
+  configurable from config.ini. Require directions on upgrading the
+  MySQL db have been documented in upgrading.txt.
 - issue2551063 - Rest/Xmlrpc interfaces needs failed login protection.
   Failed API login rate limiting with expiring lockout added. (John
   Rouillard)

--- a/doc/upgrading.txt	Sat Apr 06 20:37:45 2024 -0400
+++ b/doc/upgrading.txt	Sat Apr 06 22:47:25 2024 -0400
@@ -112,6 +112,128 @@
 
 This will insert the bad API login rate limiting settings.
 
+Update MySQL character set/collations (required)
+------------------------------------------------
+
+issue2551282_ and issue2551115_ discuss issues with MySQL's utf8
+support. MySQL has variations on utf8 character support. This
+version of Roundup expects to use utf8mb4 which is a version of
+utf8 that covers all characters, not just the ones in the basic
+multilingual plane. Previous versions of Roundup used latin1 or
+utf8mb3 (also known as just utf8). Newer versions of MySQL are
+supposed to make utf8mb4 and not utf8mb3 the default.
+
+To convert your database, you need to have MySQL 8.0.11 or newer
+(April 2018) and a mysql client.
+
+.. warning::
+
+   This conversion can damage your database. Back up your
+   database using mysqldump or other tools. Preferably on a quiet
+   database.  Verify that your database can be restored (or at
+   least look up directions for restoring it). This is very
+   important.
+
+We suggest shutting down Roundup's interfaces:
+
+  * web
+  * email
+  * cron jobs that use Python or roundup-admin
+
+then make your backup.
+
+Then connect to your mysql instance using ``mysql`` with the
+information in ``config.ini``. If your tracker's ``config.ini``
+includes::
+
+  name = roundupdb
+  host = localhost
+  user = roundupuser
+  password = rounduppw
+
+you would run some version of::
+
+  mysql -u roundupuser --host localhost -p roundupdb
+
+and supply ``rounduppw`` when prompted.
+
+With the Roundup database quiet, convert the character set for the
+database and then for all the tables. To convert the tables you
+need a list of them. To get this run::
+
+    mysql -sN -u roundupuser --host localhost -p \
+       -e 'show tables;' roundupdb > /tmp/tracker.tables
+
+The ``-sN`` removes line drawing characters and column headers
+from the output. For each table ``<t>`` in the file, run::
+
+ ALTER TABLE `<t>` CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
+
+You can automate this conversion using sed::
+
+    sed -e 's/^/ALTER TABLE `/' \
+     -e 's/$/` CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;/'\
+     /tmp/tracker.tables> /tmp/tracker.tables.sql
+
+The backticks "`" are required as some of the table names became
+MySQL reserved words during Roundup's lifetime.
+
+Inspect ``tracker.tables.sql`` to see if all the lines look
+correct. If so then we can start the conversion.
+
+First convert the character set for the database by running::
+
+  mysql -u roundupuser --host localhost -p roundupdb
+
+Then at the ``mysql>`` prompt run::
+
+  ALTER DATABASE roundupdb CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
+
+you should see: ``Query OK, 1 row affected (0.01 sec)``.
+
+Now to modify all the tables run:
+
+  \. /tmp/tracker.tables.sql
+
+You will see output similar to::
+
+  Query OK, 5 rows affected (0.01 sec)
+  Records: 5  Duplicates: 0  Warnings: 0
+
+for each table. The rows/records will depend on the number of
+entries in the table. This can take a while.
+
+Once you have successfully completed this, copy your tracker's
+config.ini to a backup file. Edit ``config.ini`` to use the defaults:
+
+ * mysql_charset = utf8mb4
+ * mysql_collation = utf8mb4_unicode_ci
+ * mysql_binary_collation = utf8mb4_0900_bin
+
+Also look for a ``~/.my.cnf`` for the roundup user and make sure
+that the settings for character set (charset) are utf8mb4 compatible.
+
+To test, run ``roundup-admin -i tracker_home`` and display an
+issue designator: e.g. ``display issue10``. Check that the text
+fields are properly displayed (e.g. title). Start the web
+interface and browse some issues. Again, check that the text
+fields display correctly, that the history at the bottom of the
+issues displays correctly and if you are using the default full
+text search, make sure that that works.
+
+If this works, bring email cron jobs etc. back online.
+
+If this fails, take down the web interface, restore the database
+from backup, restore the old config.ini. Then test again and
+reach out to the mailing list for help.
+
+We can use assistance in getting these directions corrected or
+enhanced. The core Roundup developers don't use MySQL for their
+production workloads so we count on users to help us with this.
+
+.. _issue2551282: https://issues.roundup-tracker.org/issue2551282
+.. _issue2551115: https://issues.roundup-tracker.org/issue2551115
+
 Disable performance improvement for wsgi mode (optional)
 --------------------------------------------------------
 

--- a/roundup/backends/back_mysql.py	Sat Apr 06 20:37:45 2024 -0400
+++ b/roundup/backends/back_mysql.py	Sat Apr 06 22:47:25 2024 -0400
@@ -100,9 +100,13 @@
     kwargs = connection_dict(config)
     conn = MySQLdb.connect(**kwargs)
     cursor = conn.cursor()
-    command = "CREATE DATABASE %s COLLATE utf8_general_ci" % config.RDBMS_NAME
+    command = "CREATE DATABASE %s COLLATE %s" % (config.RDBMS_NAME,
+                                                 config.RDBMS_MYSQL_COLLATION)
     if sys.version_info[0] > 2:
-        command += ' CHARACTER SET utf8'
+        charset = config.RDBMS_MYSQL_CHARSET
+        if charset == 'default':
+            charset = 'utf8mb4'  # use full utf set.
+        command += ' CHARACTER SET %s' % charset
     logging.info(command)
     cursor.execute(command)
     conn.commit()
@@ -652,11 +656,15 @@
 
 
 class MysqlClass:
-    case_sensitive_equal = 'COLLATE utf8_bin ='
+
+    case_sensitive_equal = None # defined by self.get_case_sensitive_equal()
 
     # TODO: AFAIK its version dependent for MySQL
     supports_subselects = False
 
+    def get_case_sensitive_equal(self):
+        return 'COLLATE %s =' % self.db.config.RDBMS_MYSQL_BINARY_COLLATION
+
     def _subselect(self, proptree):
         ''' "I can't believe it's not a toy RDBMS"
            see, even toy RDBMSes like gadfly and sqlite can do sub-selects...

--- a/roundup/backends/rdbms_common.py	Sat Apr 06 20:37:45 2024 -0400
+++ b/roundup/backends/rdbms_common.py	Sat Apr 06 22:47:25 2024 -0400
@@ -1643,7 +1643,9 @@
     case_insensitive_like = 'LIKE'
 
     # For some databases (mysql) the = operator for strings ignores case.
-    # We define the default here, can be changed in derivative class
+    # We define the default here, can be changed in derivative class.
+    # If set to any false value, self.get_case_sensitive_equal() is
+    # called to set its value.
     case_sensitive_equal = '='
 
     # Some DBs order NULL values last. Set this variable in the backend
@@ -1675,6 +1677,16 @@
         """
         self.do_journal = 0
 
+    def get_case_sensitive_equal(self):
+        """ For some databases (mysql) the = operator for strings ignores
+        case. We define the default here, can be changed in derivative class.
+
+        It takes config as an argument because mysql has multiple collations.
+        The admin sets both the primary and case sensitive collation in
+        config.ini for mysql.
+        """
+        raise ValueError("get_case_sensitive_equal called in error")
+
     # Editing nodes:
     def create(self, **propvalues):
         """ Create a new node of this class and return its id.
@@ -2800,10 +2812,14 @@
 
                     # now add to the where clause
                     w = []
+                    if not self.case_sensitive_equal:
+                        self.case_sensitive_equal = \
+                            self.get_case_sensitive_equal()
+                    cse = self.case_sensitive_equal
                     for vv, ex in zip(v, exact):
                         if ex:
                             w.append("_%s._%s %s %s" % (
-                                pln, k, self.case_sensitive_equal, a))
+                                pln, k, cse, a))
                             args.append(vv)
                         else:
                             w.append("_%s._%s %s %s ESCAPE %s" % (

--- a/roundup/configuration.py	Sat Apr 06 20:37:45 2024 -0400
+++ b/roundup/configuration.py	Sat Apr 06 22:47:25 2024 -0400
@@ -1495,11 +1495,23 @@
             "Name of the group to use in the MySQL defaults file (.my.cnf).\n"
             "Only used in MySQL connections."),
         (Option, 'mysql_charset', 'utf8mb4',
-            "Charset to use for mysql connection,\n"
-            "use 'default' for the mysql default, no charset option\n"
-            "is used when creating the connection in that case.\n"
+            "Charset to use for mysql connection and databases.\n"
+            "If set to 'default', no charset option is used when\n"
+            "creating the db connection and utf8mb4 is used for the\n"
+            "database charset.\n"
             "Otherwise any permissible mysql charset is allowed here.\n"
             "Only used in MySQL connections."),
+        (Option, 'mysql_collation', 'utf8mb4_unicode_ci',
+            "Comparison/order to use for mysql database/table collations.\n"
+            "When upgrading, you can use 'utf8' to match the\n"
+            "depricated 'utf8mb3'. This must be compatible with the\n"
+            "mysql_charset setting above. Only used by MySQL."),
+        (Option, 'mysql_binary_collation', 'utf8mb4_0900_bin',
+            "Comparison/order to use for mysql database/table collations\n"
+            "when matching case. When upgrading, you can use 'utf8_bin'\n"
+            "to match the depricated 'utf8mb3_bin' collation. This must\n"
+            "be compatible with the mysql_collation above. Only used\n"
+            "by MySQL."),
         (IntegerNumberGeqZeroOption, 'sqlite_timeout', '30',
             "Number of seconds to wait when the SQLite database is locked\n"
             "Default: use a 30 second timeout (extraordinarily generous)\n"