[[TOC]]
= MySQL =
Replacing the simple SQLite database with MySQL allows greater scalability

== Notes ==
 1. The databases directory contains what web2py knows about your database
 2. You need to set deployment_settings.base.migrate=True in {{{models/000_config.py}}} before you update the code and switch back to deployment_settings.base.migrate=False later on.
 3. In case of database mismatches - check the databases directory for the appropriate .table file and change accordingly.

== Installation ==
{{{
apt-get install mysql-server
}}}

=== Install phpMyAdmin ===
optional, but highly recommended for easier GUI-based administration
{{{
apt-get install phpmyadmin
}}}

=== Install Python support for MySQL ===
{{{
apt-get install python-mysqldb
}}}
or
{{{
wget http://pypi.python.org/packages/source/M/MySQL-python/MySQL-python-1.2.3.tar.gz#md5=215eddb6d853f6f4be5b4afc4154292f
tar zxvf MySQL-python-1.2.3.tar.gz
cd MySQL-python-1.2.3
python setup.py install
}}}

For Windows try this binary:
 * http://www.thescotties.com/mysql-python/test/MySQL-python-1.2.3c1.win32-py2.6.exe
=== Create the database ===
Database should be created within MySQL before Web2Py can see it to add the relevant tables:
{{{
mysql -u root -p
 CREATE DATABASE sahana;
 GRANT SELECT,INSERT,UPDATE,DELETE,CREATE,ALTER,DROP ON sahana.* TO 'sahana'@'localhost' IDENTIFIED BY 'mypassword';
 FLUSH PRIVILEGES;
}}}

=== Configure Eden ===
Connection pools allow connections to be reused.

The number used is defined in {{{models/000_config.py}}}

==== How many pools? ====

Whatever you choose, it always starts with one and grows with the number of concurrent requests up to the value of pools (the max number of concurrent pools). So pools should be the max number of concurrent requests you expect. That is the max value of:
{{{
<number of requests/second> / <average time per request in seconds>
}}}

== Optimisation ==
For Production instances, give the MySQL database plenty of RAM:
{{{
innodb_buffer_pool_size = 2048M
innodb_file_per_table
innodb_thread_concurrency = 8
}}}

Index columns which are sorted on (especially on tables with many records) [we sort by name in most dropdowns]:
 * gis_location.name
 * pr_person.first_name
 * pr_person.middle_name
 * pr_person.last_name
{{{
ALTER TABLE `gis_location` ADD INDEX ( `name` );
ALTER TABLE `pr_person` ADD INDEX ( `first_name` );
ALTER TABLE `pr_person` ADD INDEX ( `middle_name` );
ALTER TABLE `pr_person` ADD INDEX ( `last_name` );
}}}

== Troubleshooting ==
Can view the list of expensive queries using: ''tbc''

== Replication ==
In order to have a backup instance, configure replication from the Master node to a Backup node:
 * http://www.debiantutorials.net/mysql-database-replication-masterslave/
 * http://www.howtoforge.com/how-to-repair-mysql-replication

=== On Master: ===
{{{
pico /etc/mysql/my.cnf
#bind-address = 127.0.0.1
server-id = 1
log_bin = /var/log/mysql/mysql-bin.log
binlog_do_db = sahana

/etc/init.d/mysql restart

mysql -u root -p
GRANT REPLICATION SLAVE ON sahana.* to username@'sl.av.e.ip' IDENTIFIED BY 'mypassword';
FLUSH PRIVILEGES;
SHOW MASTER STATUS;
}}}
Read log filename & position for configuring the slave (see below).

=== On Slave: ===
{{{
pico /etc/mysql/my.cnf
server-id = 2
master-host = ma.st.er.ip
master-user = username
master-password = mypassword
master-connect-retry = 60
replicate-do-db = sahana

/etc/init.d/mysql restart

mysql -u root -p

SLAVE STOP;
CHANGE MASTER TO MASTER_HOST='ma.st.er.ip', MASTER_USER='username', MASTER_PASSWORD='mypassword', MASTER_LOG_FILE='log_file', MASTER_LOG_POS=log_position;
SLAVE START;

crontab -e 
# m h  dom mon dow   command
55 * * * * /home/instance/scripts/automysqlbackup
55 * * * * /home/instance/scripts/sync-dir
}}}

=== IP Failover ===
Can configure the slave to adopt the same IP as the master using a Heartbeat:
 * http://www.srg.cs.hku.hk/srg/html/cprobe/ha/GettingStarted.html

If using Slicehost:
 * http://articles.slicehost.com/2008/10/28/ip-failover-slice-setup-and-installing-heartbeat

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InstallationGuidelines

DeveloperGuidelinesDataMigration