5个mysql基本参数的设置

key_buffer_size

We have as a pre-cursor to the top 5, the key_buffer_size. The key_buffer_size is used to store MyISAM Indexes, and is assigned as MySQL server startup. Setting this value to large is a waste of space, setting this too small will increase the amount of disk I/O. In this example, the total index space was around 100MB, so setting the value to 384-512M supports adequate growth. The default value for 5.0.67 is 8M. When you read on, see point 5, you may well consider lowering this value.

1. log-bin=/path/to/dir/file-prefix

If you are storing data in a database I’m sure you want to keep it. log-bin is necessary for point in time recovery. Period. You should also specify the actually path, and store this outside of the default MySQL data directory. The default is NOT enabled.

2. myisam_recover = force,backup

MyISAM is not the most optimal storage engine for online systems. This is a much larger discussion however for the stock default WP and general LAMP products we start with MyISAM. Setting myisam_recover will improve one disadvantage of MyISAM and that is the recovery on startup. The default is NOT enabled.

3. query_cache_size = 64M

In absence of greater information, enabling the Query Cache in a generally high read environment is a good starting point. You have the ability to set and unset this dynamically on a running server, so it is easy to remove if performance is not the optimal. You should also not go overboard with the size of the query cache. Start with a modest amount, such as 64M, assess the impact of the QC and re-assess the value. The default is NOT enabled. The Query Cache also uses the variables query_cache_type, which defaults to ON, and query_cache_limit which defaults to 1M.

4. table_cache=1024

The MU part of the WordPress is a trigger that the system will have several hundred tables. Monitoring Opened_tables, and Open_tables is as easy check to determine a more appropriate table_cache value. The default value on 5.0.67 is 64.

5. max_connections=150

This was a difficult choice, the first 4 are obvious for the current environment.

I have to question the reason why max_connections=500. Given that there is no other configuration settings, why would this value be so large. Start with a more realistic figure, such as the default of 150, and monitor max_used_connections, threads_running for a while. A review of the H/W confirmed this is unrealistic, the system has 16GB of RAM, but only a 32bit OS.