In this post, I want to explore a way to establish 100,000 connections to MySQL. Not just idle connections, but executing queries.

100,000 connections. Is that really needed for MySQL, you may ask? Although it may seem excessive, I have seen a lot of different setups in customer deployments. Some deploy an application connection pool, with 100 application servers and 1,000 connections in each pool. Some applications use a “re-connect and repeat if the query is too slow” technique, which is a terrible practice. It can lead to a snowball effect, and could establish thousands of connections to MySQL in a matter of seconds.

So now I want to set an overachieving goal and see if we can achieve it.

Setup

For this I will use the following hardware:

Bare metal server provided by packet.net, instance size: c2.medium.x86
Physical Cores @ 2.2 GHz
(1 X AMD EPYC 7401P)
Memory: 64 GB of …

As a DBA, your top priority is to keep your databases and dependent applications running smoothly at all times. To this end, your best weapon is judicious monitoring of key performance metrics. In a perfect world, you’d want to be up-to-date regarding every aspect of your database’s activity – i.e. how many events occurred, how big they were, precisely when they happened and how long they took.

There certainly is no shortage of tools that can monitor resource consumption, provide instantaneous status snapshots, and generate wait analysis and graphs. The challenge is that some metrics can be expensive to measure, and, perhaps even more importantly, they can require a lot of work to analyze.

The purpose of Part-2 of the blog series is to narrow down the field to those performance metrics that provide the most value for the effort as well as present some tangible ways to capture and study them. It is by tracking the most useful …

In this blog post, we’ll look at how ProxySQL improves MySQL SSL connection performance.

When deploying MySQL with SSL, the main concern is that the initial handshake causes significant overhead if you are not using connection pools (i.e., mysqlnd-mux with PHP, mysql.connector.pooling in Python, etc.). Closing and making new connections over and over can greatly impact on your total query response time. A customer and colleague recently educated me that although you can improve SSL encryption/decryption performance with the AES-NI hardware extension on modern Intel processors, the actual overhead when creating SSL connections comes from the handshake when multiple roundtrips between the server and client are needed.

With ProxySQL’s support for SSL on its backend connections and connection pooling, we can have it sit in front of any application, on the same server (illustrated below):

…

This blog post looks at SSL connections and how they work in MySQL 5.7.

Recently I was working on an SSL implementation with MySQL 5.7, and I made some interesting discoveries. I realized I could connect to the MySQL server without specifying the SSL keys on the client side, and the connection is still secured by SSL. I was confused and I did not understand what was happening.

In this blog post, I am going to show you why SSL works in MySQL 5.7, and it worked previously in MySQL 5.6.

Let’s start with an introduction of how SSL worked in 5.6.

SSL in MySQL 5.6

The documentation for SSL in MySQL 5.6 is quite detailed, and it explains how SSL works. But first let’s make one thing …

The MySQL server supports a variety of client connection methods. To summarize: you have TCP/IP (v4 and v6) on all OSes (with or without TLS/SSL encryption), Unix Domain Sockets on Unix/Linux, and Named Pipes and/or Shared Memory on Windows.

Each of these connection methods has its own set of pros and cons: speed, security, portability, and ease-of-use.…

Stop increasing max_connections every time there’s a 1040: Too Many Connections error. Every additional connection is another share to further divide the available memory.

Instead, while it would be best to manage the workload, it is also reasonable to properly utilize the available hardware with good server configuration.

There are three relevant server configuration options for managing connection counts as they relate to satisfying web requests.

1. max_connections – the queue depth
2. innodb_thread_concurrency – the count of queue consumers
3. innodb_concurrency_tickets – the amount of work a consumer can do on a query before switching to the next query request

Correctly configuring these three variables, and controlling your workload of course, can prevent 1040 Too many connections errors, assuming, …

Why is it so important to close connections to databases if there’s no explicit need to keep them open (which usually the case)?

Symptoms

• Icinga reports high usage of allowed connections (>90%) on master MySQL server.
• No running queries or any specific in processlist. All the connections are sleeping from the same servers.
• The number of connections was 20 times more than the usual

Root cause

There was tremendous amount of queries doing “copying to tmp table” on the slaves. The connections were opened to both master and slaves and waiting for the slaves to answer the query the connections to master was kept opened. So the sleeping connections was piled up to the limit of max connections.

Lesson

1. When troubleshooting always check slaves too.
2. Close unused connections especially for masters.
3. Keep your query optimized and …

Hi all,

I was asked this question in an e-mail — feel free to ask your questions in the comments, as I will point the original author to this post to answer those questions. There is not a lot of data here, so instead of me asking questions in an e-mail I figured I would open it up to the (MySQL) world. Without further ado, here’s the question:

Basically when we open more than one connection- we’re opening 5, and we do processing in mysql (innodb tables) the server cpu and memory max out and the processing grinds to a halt. One connection at a time is able to run well- even with lots of data. But once we try to process data under 5 concurrent connections, mysql gets bogged down to the point where it’s barely usable.

I’ve researched this and found a number of opinions, including whether this is just poor performance due to where the we are in the 5.1 life cycle (i.e. energies have gone into fixing big bugs not …