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MySQL Upgrade

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MySQL Upgrade

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MySQL 8.4 disables AHI – Why and What you need to know

Kedar
January 19, 2026

MySQL 8.4 changed the InnoDB adaptive hash index (innodb_adaptive_hash_index) default from ON to OFF, a major shift after years of it being enabled by default. Note that the MySQL adaptive hash index (AHI) feature remains fully available…

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A Unique Foreign Key issue in MySQL 8.4

Kedar
April 24, 2025

Recently, a friend reached out to me for help after encountering an error while restoring a MySQL dump during an upgrade from MySQL 8.0 to 8.4. The error read: At…

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MySQL 8 utf8mb4_0900_ai_ci collation confusion

Kedar
November 18, 2024

Recently I was asked a question: Why am I getting utf8mb4_0900_ai_ci as the default collation in MySQL 8, despite setting the server to use utf8mb4_general_ci? With the upgrade to MySQL…

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Understanding Return Codes of pt-upgrade: A quick guide

Kedar
October 14, 2024

Interpreting the results and exit codes of your upgrade tests is essential for assessing the process’s outcome. In this blog, we’ll explore the significance of pt-upgrade return codes and how…

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How to save money in AWS RDS – Upgrade to MySQL 8

Kedar
February 8, 2024

MySQL 8 is around us for 5 years now. I believe you’re surely considering an upgrade. But if you’re on AWS and still on an older version of MySQL, this…

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MySQL 8 – timestamp cannot be null and explicit_defaults_for_timestamp

Kedar
March 20, 2023

A friend’s application started failing with MySQL causing error about timestamp columns and it needs urgent fixing from the database side. A timestamp column was not accepting the null values…

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