known-issues-list.md

@@ -13,21 +13,37 @@ of MariaDB, attempts to create or update the database will fail with the error `
 
 * Some unit tests fail when using MySQL's latest release as of September 19 versioned 8.0.22. This is under investigation in #1570.
 
+## Kea 1.9.10 & 1.9.11
+
+* If, using configuration backend on Kea 1.9.10 or 1.9.11, you managed to add a client class with associated option data, and then removed the client class, you would be left with dangling option data rows in the database. Option data rows are now properly removed when the associated client class is removed after #2094 which was released with 2.0.0. The foreign key constraint which helps realize the cascading delete will fail to be created on upgrade to the new schema with the following error:
+
+```sh
+Processing /opt/kea/share/kea/scripts/mysql/upgrade_011_to_012.sh file...
+ERROR 1452 (23000) at line 16: Cannot add or update a child row: a foreign key constraint fails (`keatest`.`#sql-alter-1-2`, CONSTRAINT `fk_dhcp4_options_client_class` FOREIGN KEY (`dhcp_client_class`) REFERENCES `dhcp4_client_class` (`name`) ON DELETE CASCADE ON UPDATE)
+```
+
+The workaround is to delete the dangling options before retrying the upgrade:
+
+```sql
+DELETE FROM dhcp4_options WHERE scope_id = 2 AND dhcp_client_class NOT IN (SELECT name FROM dhcp4_client_class);
+DELETE FROM dhcp6_options WHERE scope_id = 2 AND dhcp_client_class NOT IN (SELECT name FROM dhcp6_client_class);
+```
+
 ## Kea 1.9.4
 
 * The ``kea-admin`` command may fail to upgrade database schema due to missing execute permission on the upgrade scripts. This can be fixed by setting the execute flag. e.g.
 
-```
-chmod u+x {prefix}/share/kea/scripts/mysql/*.sh
-chmod u+x {prefix}/share/kea/scripts/pgsql/*.sh
-chmod u+x {prefix}/share/kea/scripts/cql/*.sh
+```sh
+$ chmod u+x {prefix}/share/kea/scripts/mysql/*.sh
+$ chmod u+x {prefix}/share/kea/scripts/pgsql/*.sh
+$ chmod u+x {prefix}/share/kea/scripts/cql/*.sh
 ```
 
 The fix for this is already available in #1681 and will be included in the upcoming 1.9.5 release.
 
 * If upgrading from 1.9.2 or 1.9.3 the MySQL schema upgrade will fail. This is a bug in the upgrade script that will be fixed in upcoming 1.9.5 release. See #1698 for details. Alternatively, the schema can be fixed manually, by issuing the following SQL commands:
 
-```
+```sql
 ALTER TABLE dhcp4_subnet
     ADD COLUMN cache_threshold FLOAT DEFAULT NULL,
     ADD COLUMN cache_max_age INT(10) DEFAULT NULL;
@@ -47,7 +63,7 @@ ALTER TABLE dhcp6_shared_network
 
 The above snippet can be written to a kea1.9.4-schema-fix.mysql file and then applied using the following command:
 
-```
+```sh
 $ mysql -u DBUSER -p DBNAME < kea1.9.4-schema-fix.mysql
 ```