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3 Ways to Optimize MySQL Performance: Max Connections

In this blog post, we’ll wrap up our three-part series discussing how you can optimize the performance of your MySQL environment. In case you missed our other two posts, check them out:

  • Indexing: See how indexing can impact your MySQL environment and how you can set up your indexes so that they contribute to better performance
  • Buffer Pool Size: Learn why buffer pool size matters — including how you can define it within your environment and associated best practices


After talking through indexing and buffer pool size, this post will cover max connections — a setting that often gets skipped over but offers many benefits for your MySQL performance.  


Resolving “Too Many Connections” Error

Have you tried connecting to your MySQL server only to get the annoying error, “too many connections”? This means that the number of available connections are in use by other clients on the server. And it can be quite annoying to get this error — especially when you have an urgent need to access your MySQL environment.

Luckily, you can easily fix this with the max_connections setting in your environment. Before you get started, there are a few things to know about the max_connections setting.


Max Connections 101

Many database administrators (DBAs) often overlook the max_connections setting in MySQL, mostly because the default value — 151 — is high enough that most databases don’t hit the maximum connections.

However, many applications that connect to the database don’t close their connection. Over time, this means the number of connections that you have for your MySQL database are increasing rapidly — particularly as more applications depend on the database that you have set up.

Whether you have a number of applications accessing your MySQL database or if you have a database that is hit frequently for other reasons, ensure that you have a buffer between your average connections and your max connections. Leveraging a database monitoring tool like SelectStar, you can gather the data you need to determine your average connections.

Accessing key information like this can help you determine the average connections that your system experiences, as well as how your connections are increasing over time. Armed with this data, you can increase your max connections value to ensure you are not close to preventing connections to the database.

Ready to adjust your max connections? I recommend checking out this guide from MySQL. It  offers everything that you need to know, from receiving the “too many connections” error to changing the value in your system to accommodate the number of connections that you need.


Need more visibility into your max connections for your MySQL environment? Try a free trial of SelectStar to get this information — and more — to optimize performance across your databases.



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