What is Throughput?

MySQL Throughput, quantified as Queries per Second (QPS), is a performance metric that plays an important role when monitoring and tuning your MySQL databases. In other words, it measures the volume of queries your database can handle within a second.

Throughput is key to understanding the workload your database can support. High throughput rates signify a well-optimized database, whereas low throughput could indicate potential bottlenecks or other performance issues that need addressing.

Why is Throughput Important for Monitoring and Tuning?

• Capacity Planning – Understanding the maximum throughput your MySQL database can handle helps in planning for scale. It informs decisions about when to scale up (increase resources) or scale out (add more database instances) based on expected load increases.
• Performance Benchmarking – Throughput provides a quantifiable measure of database performance, making it easier to benchmark and compare the efficiency of different configurations, hardware, or optimization strategies.
• Detecting Bottlenecks – A sudden drop in QPS could indicate a bottleneck in the database system, such as inefficient queries, hardware limitations, or configuration issues. Monitoring throughput enables quick identification and resolution of such problems.
• Optimizing Resources – By understanding the throughput capabilities of your MySQL database, you can better allocate resources without overprovisioning, thus managing costs more effectively.

The Role of the RED Method in Throughput Analysis

The RED Method is a monitoring strategy that was primarily designed for microservices architectures, but it can be effectively applied to a wide range of systems, including databases like MySQL. It focuses on three key metrics that provide insights into the health and performance of services.

The acronym "RED" stands for Request Rate, Error Rate, and Duration:

• Rate – The frequency of requests or queries a system processes within a specific timeframe, indicating the system's workload.
• Error Rate – The frequency of requests or queries a system processes within a specific timeframe, indicating the system's workload.
• Duration – The average time taken to respond to requests, reflecting the system's performance and efficiency.

By focusing on these three metrics, the RED Method provides a framework that helps administrators quickly understand the operational state of their database – supporting proactive monitoring and problem-solving.

Releem uses the RED Method as its monitoring strategy for databases.

How Releem Calculates Throughput

Releem calculates this Rate value by extracting the "Questions" variable from the MySQL SHOW GLOBAL STATUS command. This variable tallies the total number of statements processed by the server since its last startup, encompassing both client-sourced statements and those executed within stored procedures. The throughput, or QPS, can then be calculated by measuring the change in the "Questions" value over time.

The SQL query to retrieve the "Questions" variable looks like this:
SHOW GLOBAL STATUS LIKE 'Questions';

By executing this command at two intervals, say T1 and T2, and subtracting the Questions value at T1 from that at T2, you get the total number of queries executed during that period. Dividing this number by the number of seconds between T1 and T2 gives you the average QPS (Queries per Second).

Step-By-Step Example

• Initial Measurement (T1) – At 10:00 AM, you execute SHOW GLOBAL STATUS LIKE 'Questions'; and receive a result indicating that 100,000 queries have been processed since the MySQL server started.

T1 = 100,000 queries

• Second Measurement (T2) – At 10:05 AM, you execute the same command again and find out that the total number of processed queries has increased to 120,000.

T2 = 120,000 queries

• Calculate the Difference in Queries – Subtract the initial query count from the second to find the total number of queries processed during this period.

120,000−100,000 = 20,000 queries

• Calculate the Time Interval in Seconds – Since the measurements were taken 5 minutes apart, convert this interval to seconds for the QPS calculation.

5 minutes = 300 seconds

• Compute the Average QPS – Divide the total number of queries by the elapsed time in seconds to find the average QPS.

20,000 queries / 300 seconds = 66.67 QPS

Let Releem Calculate and Monitor Throughput Automatically

Managing a MySQL database effectively requires constant monitoring, detecting performance issues and optimization, tasks that can be both time-consuming and complex. This is where Releem steps in – offering a comprehensive solution to automate these processes. Releem calculates QPS and uses throughput data and trends to make configuration suggestions that can dramatically improve your database performance.