Solutions to Common MySQL Problems

MySQL is one of the most popular database engines, and with good reason. Once configured properly, it can help connect thousands of databases to servers and do so at relatively low cost. Plus, since it’s such a common tool, you’re unlikely to run into issues where servers don’t recognize it or you can’t get help configuring it to do what you want it to do. Sometimes, though, you will run into errors–especially configuration errors–that can be frustrating or confusing. If you’re having a hard time with MySQL, you may be running into one of these common problems.

Problem #1: High disk usage. Some MySQL users find that as they expand their operations, using MySQL for a large number of databases, it begins to take up too much disk space. Servers begin looking for data on different parts of the disk at the same time, which can slow or completely halt disk operation.

Solution: Configure MySQL to work mainly with memory, not disks.MySQL takes up far less memory than it does disk space, so the more you can get it to use your computers’ RAM instead of looking for data on disks, the more smoothly it will run. In particular, MySQL can be configured to use available RAM whenever possible and to put temporary tables in memory instead of on hard disks. If you have RAM available on your servers, this solution should speed things up. Just remember that the more databases you have, the more memory MySQL will need.

Problem #2: Losing connection to the server. If MySQL loses its connection to the server in the middle of data transfers, it will generate error messages instead of transferring the data as needed. This can be the result of a network problem, so your first step is always to check your network connections. If this problem occurs frequently, however, you may need to reconfigure MySQL.

Solution: Lost connections often happen because MySQL is configured to time out after only 30 seconds, which may not be enough time for large data transfers. Try configuring net_read_timeout to 60 seconds or longer. If you are timing out on initial connect, reconfigure connect_timeout to at least 10 seconds. This often happens if your connection is slow, so consider upgrading your network to connect faster as well.

Problem #3: Getting a “too many connections” error. As you expand your operations, you may need more computers to be able to connect to MySQL. If you don’t reconfigure MySQL, it will refuse some of these connections and generate a “too many connections” error message.

Solution: Reconfigure MySQL to accept more connections. To do this, change your max_connections variable. The default is 151; you can set it to whatever number accommodates the number of connections you need. You may also need to increase your open_files_limit to accommodate the number of connections open on your server at the same time.