MySQL

The 5.1 release was very slow getting released

• Percona did work on innodb XtraDB plugin
• Google did patches
• Facebook did a patch set
• Monty Program - New company started by the founder of MySQL, Forked Maria

MySQL 5.1 Sun/Oracle version we now consider it stable

Oracle bought MySQL, and it has gone OK so far.

Use the Innodb Plugin is much better performance than the included version.

MySQL 5.4

Join Optimizations, Stored Procedures, General Scalability Improvements

MySQL 5.5

• SemiSync Replication
• Perf Schema
• MRS (multiple Rollback Segments), InnoDB Recovery, Delete Buffer, MDL, Split InnoDB Buffer Pools (based on the number of buffer pools you want), InnoDB as Default

Useful SQL for DBAs

List all tables in the current database:

=> SELECT tablename FROM pg_tables where tablename not like 'pg_%';

Limit rows returned as in where rownum <= 10

=> select tablename from pg_tables limit 10;

List tables in one schema

=> select tablename from pg_tables where tableowner='qedit';

List running queries

=> select * from pg_stat_activity;

List database activity

Run the command to install procedural languages or you will get:
ERROR: language "plpgsql" does not exist

Connect as the superuser
bash-3.2$

Run the command
bash-3.2$ createlang -d movecms1 plpgsql

Login as regular user
bash-3.2$ psql -U qedit -d movecms1

Now create the type to return the values

Installing PostgreSQL on Fedora Core

This will install the PostgreSQL database server and the component required to write PHP scripts that communicate with postgres. We use yum to handle dependencies and gather all of the required packages. For more information on PostgreSQL, see http://www.postgresql.org

1. Install PostgreSQL and the component that allows php to talk to PostgreSQL.

 yum -y install postgresql postgresql-server php-pgsql 

2. Configure the new service to start automatically

  /sbin/chkconfig postgresql on
  /sbin/chkconfig postgresql initdb
  /sbin/service postgresql start

3. Start the postgresql interactive shell and create your first user and database.

Before you go any further backup your database before doing any steps below. If you 'splode your database for any reason, you'll need it.

Here are the steps:

1. Shutdown MySQL

2. Move/copy/change the name of ib_logfile0 and ib_logfile1 files. (find where MySQL exists on your system - locations can vary greatly). MySQL will recreate these files when you start it up again. Not anytime you change the innodb_log_file_size parameter you will need to shutdown MySQL, move these files, and start up MySQL again.

3. Tune it up a bit
Based on a lot of searching around and benchmarking with JMeter I arrived at the setting below for running on my Macbook Pro. See the links at the end of this post for articles which can help you determine what to adjust these numbers to for other machines (ones with more RAM/CPU, for instance. The production server for this particular site ended up with 5000M setting for innodb_buffer_pool_size. So settings will, and should, vary greatly just depending).