How to setup the MySQL database for GNUnet. NOTE: This db module does NOT work with mysql before 4.1 since we need prepared statements. We are generally testing the code against MySQL 5.0 at this point. HIGHLIGHTS Pros + On up-to-date hardware where mysql can be used comfortably, this module will have better performance than the other db choices (according to our tests). + Its often possible to recover the mysql database from internal inconsistencies. The other db choices do not support repair (gnunet-check cannot fix problems internal to the dbmgr!). For example, we have seen several cases where power failure has ruined a gdbm database beyond repair. + much faster (for one of the key benchmarks -- content migration -- we have measure mysql taking 2s for an operation where sqlite takes 150s). Cons - Memory usage (Comment: "I have 1G and it never caused me trouble") - Manual setup MANUAL SETUP INSTRUCTIONS 1) in /etc/gnunet.conf, set DATABASE = mysql 2) Then access mysql as root, $ mysql -u root -p and do the following. [You should replace $USER with the username that will be running the gnunetd process]. CREATE DATABASE gnunet; GRANT select,insert,update,delete,create,alter,drop,create temporary tables ON gnunet.* TO $USER@localhost; SET PASSWORD FOR $USER@localhost=PASSWORD('$the_password_you_like'); FLUSH PRIVILEGES; 3) In the $HOME directory of $USER, create a ".my.cnf" file with the following lines [client] user=$USER password=$the_password_you_like Thats it. Note that .my.cnf file is a security risk unless its on a safe partition etc. The $HOME/.my.cnf can of course be a symbolic link. Even greater security risk can be achieved by setting no password for $USER. Luckily $USER has only priviledges to mess up GNUnet's tables, nothing else (unless you give him more, of course). 4) Still, perhaps you should briefly try if the DB connection works. First, login as $USER. Then use, $ mysql -u $USER mysql> use gnunet; If you get the message "Database changed" it probably works. [If you get "ERROR 2002: Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)" it may be resolvable by "ln -s /var/run/mysqld/mysqld.sock /tmp/mysql.sock" so there may be some additional trouble depending on your mysql setup.] 5) If you want to run the testcases, you must create a second database "gnunetcheck" with the same username and password. This database will then be used for testing ("make check"). REPAIRING TABLES - Its probably healthy to check your tables for inconsistencies every now and then, especially after system crashes. - If you get odd SEGVs on gnunetd startup, it might be that the mysql databases have been corrupted. - The tables can be verified/fixed in two ways; 1) by shutting down mysqld (mandatory!) and running # myisamchk -r *.MYI in /var/lib/mysql/gnunet/ (or wherever the tables are stored). Another repair command is "mysqlcheck". The usable command may depend on your mysql build/version. Or, 2) by executing mysql> REPAIR TABLE gn090; PROBLEMS? If you have problems related to the mysql module, your best friend is probably the mysql manual. The first thing to check is that mysql is basically operational, that you can connect to it, create tables, issue queries etc.