Did you ever need to determine the performance of a query over time? One of the problems with database query optimizations is that the underlying data is always churning. Add in an increase in the number of users, expanding server demand use, and other items that impact your query. What was optimized is no longer performing as expected.

MySQL added a JSON format option to the output of the EXPLAIN command quite a while ago. More recently, Oracle added the feature of saving the output into a variable (see https://dev.mysql.com/doc/refman/9.0/en/mysql-nutshell.html and https://dev.mysql.com/blog-archive/explain-into-and-explain-for-schema-in-mysql-81-and-82). This provides a way to access the data in that variable and plop it into a database. The saved result can be compared to current or other past responses for analysis. 

mysql> explain format=json into @var
       SELECT * from …

At Percona, we’ve always prioritized performance, and recent trends in MySQL’s development have been a point of concern for us. In particular, the performance deterioration in the MySQL 8.4.x and 9.y versions caught our attention, as highlighted in Marco Tusa’s insightful blog post, Sakila, Where Are You Going? We’re pleased to report that the latest […]

Used to be that replication lag was as simple as Seconds_Behind_Master (renamed to Seconds_Behind_Source). But with multi-threaded replication (MTR) this is no longer the case. It’s time to relearn replication lag monitoring using Performance Schema tables.

This blog post explains the cause of “ERROR 1412 (HY000): Table definition has changed, please retry transaction” with the specific Isolation level settings. Background As per the MySQL documentation, this error should occur for “operations that make a temporary copy of the original table and delete the original table when the temporary copy is built.” […]

Let’s stay a bit longer with MySQL 3.2x to advance the MySQL Retrospective in anticipation of the 30th Anniversary. The idea of this article was suggested to me by Daniël van Eeden. Did you know that in the early days, and therefore still in MySQL 3.20, MySQL used the ISAM storage format? IBM introduced the […]

This blog is not intended to offer anything extraordinary; instead, consider it an anecdote, a lesson, or simply a proper way of doing things without the need to run a test when in doubt. That said, I must emphasize that, as always, testing everything before deploying to production is essential. Let’s dive into the story: […]

To further advance the MySQL Retrospective in anticipation of the 30th Anniversary, today, let’s discuss the very first version of MySQL that became availble to a wide audient though the popular InfoMagic distribution: MySQL 3.20! In 1997, InfoMagic incorporated MySQL 3.20 as part of the RedHat Contrib CD-ROM (MySQL 3.20.25). Additionally, version 3.20.13-beta was also […]

In this series, “MySQL with Diagrams,” I’ll use diagrams to explain internals, architectures, and structures as detailed as possible. In basic terms, here’s how replication works: the transactions are written into a binary log on the source side, carried into the replica, and applied. The replica’s connection metadata repository contains information that the replication receiver […]

So, as you’ve noticed, I’ve been playing around with MySQL Router v8.4.3 and read-write splitting, and now I’ve come across some issues that my environment has generated and I’ve opened some bugs against the fiend:

Bug 116950 – Router Read-Write splitting config causes PHP RSET_HEADER error

Bug 116951 – mysqlrouter Error parsing stats_updates_frequency errors

Bug 116952 – Router w/ RW split causes ERROR: 4501 if sql script contains comments lines (“– “)

(Yup, I prepared each bug description, repeatable tasks and suggested fix …

This tutorial explores HeatWave GenAI, a cloud service that simplifies interacting with unstructured data using natural language. It combines large language models, vector stores, and SQL queries to enable tasks like content generation, chatbot, and retrieval-augmented generation (RAG). The focus is on RAG and how HeatWave GenAI’s architecture helps users gain insights from their data.

The post Simplifying AI Development: A Practical Guide to HeatWave GenAI’s RAG & Vector Store Features first appeared on dasini.net - Diary of a MySQL expert.