During the mysqld restart all OQGraph contents are lost. When I insert something into table, everything is OK and I can use all the OQGraph features, but only until mysqld restart. Then I have to re-insert all the data.
Tested on Debian Squeeze (5.2.3-MariaDB-mariadb90-log) and Ubuntu Maverick (5.2.3-MariaDB-mariadb87-log).

MariaDB [DBName]> select count from ReactionGraph \G

• • • • • • • • • • • • • • • • • • • • • • • • • • • 1. row ***************************
                                                      count: 0
                                                      1 row in set (0.00 sec)

MariaDB [DBName]> show create table ReactionGraph \G

• • • • • • • • • • • • • • • • • • • • • • • • • • • 1. row ***************************
                                                             Table: ReactionGraph
                                                      Create Table: CREATE TABLE `ReactionGraph` (
                                                        `latch` smallint(5) unsigned DEFAULT NULL,
                                                        `origid` bigint(20) unsigned DEFAULT NULL,
                                                        `destid` bigint(20) unsigned DEFAULT NULL,
                                                        `weight` double DEFAULT NULL,
                                                        `seq` bigint(20) unsigned DEFAULT NULL,
                                                        `linkid` bigint(20) unsigned DEFAULT NULL,
                                                        KEY `latch` (`latch`,`origid`,`destid`) USING HASH,
                                                        KEY `latch_2` (`latch`,`destid`,`origid`) USING HASH
                                                      ) ENGINE=OQGRAPH DEFAULT CHARSET=utf8
                                                      1 row in set (0.00 sec)

MariaDB [DBName]> insert into ReactionGraph (origid,destid,weight) (select ... ) \G
Query OK, 16545 rows affected (1.13 sec)
Records: 16545 Duplicates: 0 Warnings: 0

MariaDB [DBName]> exit
Bye
torkvemada@host ~ $ sudo service mysql restart
Stopping MariaDB database server: mysqld.
Starting MariaDB database server: mysqld.
Checking for corrupt, not cleanly closed and upgrade needing tables..
torkvemada@host ~ $ mysql -uroot DBName
MariaDB [DBName]> select count from ReactionGraph \G

• • • • • • • • • • • • • • • • • • • • • • • • • • • 1. row ***************************
                                                      count: 0
                                                      1 row in set (0.00 sec)