The latest from the MySQL community

Two recent posts on the Percona blog caught my attention. In Replicating from InnoDB into a DuckDB storage engine and The DuckDB MySQL engine at 500 GB, Evgeniy Patlan wired DuckDB into mysqld as a storage engine, pointed row-based replication at it, and measured it at TPC-H scale factor 500. The numbers are striking: loads 25 times faster than InnoDB, one fifth of the disk, and the full 22-query TPC-H suite done in 186 seconds where InnoDB needed about 28 hours and never finished four of the queries.

The posts are also honest about the cost. The work is experimental. The worst bug found was silent data loss on every replicated transaction: the two-phase commit code for mixed-engine transactions dropped prepared DuckDB transactions …

This article is also available in Chinese: 中文版. Browse all English articles.

Have you ever run into a mysqld process that has been starting for a long time and still won’t come up? When that happens, you can use perf top to check what the MySQL process is mainly doing. If what you see looks like the figure below — the MySQL main thread (the one starting from mysqld_main) spending the vast majority of its time rolling back transactions — then you are very likely hitting a large-transaction rollback.

The most common way to get here is a large transaction that fills up the disk while writing its binlog, crashing the instance. The largest binlog file I have run into was over 114GB. Since the Binlog Cache’s …

This article is also available in Chinese: 中文版. Browse all English articles.

Large transactions are a notorious problem in MySQL: they cause not only replication lag but also stability problems. A previous article, MySQL Large Transaction Commit Optimization, covered the problems a large transaction causes at commit time and the optimizations we made in AliSQL. This article looks at the problems a large transaction causes during semi-synchronous replication, and how AliSQL solves them.

In MySQL Large Transaction Commit …

This article is also available in Chinese: 中文版. Browse all English articles.

If you use and operate MySQL, you’ve surely run into a strange slow query like this:

• An INSERT that’s normally instant took 1.3s, and the slow-query log shows no long lock wait.
• Every statement in a multi-statement transaction had already finished, yet the COMMIT alone took 1.3s.

When this happens, the most likely cause is a large transaction committing. Below is a simulated test: we used sysbench to simulate a normal workload, then ran a large UPDATE in the background every 5 seconds. You can see the large UPDATE severely hurts performance.

Root Cause

The …

As promised, my slides from FOSDEM25 and Pre-FOSDEM MySQL Belgian Days :

• MySQL Scalability & Systems Evaluation Overview 2025 [PDF]
• Profiling MySQL Memory & CPU Usage Directly From MySQL [PDF}

And since I was asked several times about MySQL test case demonstrating glibc-malloc memory fragmentation / leaks -- here are all the details :

Read more... (4 min remaining to read)

In MySQL 8.0 we introduced a totally new design for InnoDB REDO Log management. The main difference was about implementing a lock-free solution for user threads, and use dedicated REDO threads for all background IO write work.

for more details, see an excellent and very detailed article by Pawel : https://dev.mysql.com/blog-archive/mysql-8-0-new-lock-free-scalable-wal-design/

However, over a time we also added an option to let users to switch REDO threads=OFF to enforce REDO log processing efficiency in some particular cases. Unfortunately this feature created a lot of confusions for MySQL users, and many ones interpreted this in different ways, providing different and sometimes opposite advices, etc..

My main advice will be always : test each feature yourself and within your …

Just about a month ago, Pavel Ivanov released Ripple under the Apache-2.0 license. Ripple is a MySQL binlog server: software which receives binary logs from MySQL or MariaDB servers and delivers them to another MySQL or MariaDB server. Practically ,this is an intermediary master which does not store any data, except the binary logs themselves, and does not apply events. This solution allows saving of a lot of resources on the server, which acts only as a middle-man between the master and its actual slave(s).

The intermediary server, keeping binary logs only and not doing any other job, is a prevalent use case which allows us to remove IO (binlog read) and network (binlog retrieval via network) load from the actual …

The encrypted binary log file format introduced in MySQL version 8.0.14 was designed to allow a “manual” decryption of the file data when the value of the key that encrypted its file password is known.

Each encrypted binary (or relay) log file is composed by an encrypted binary log file header and the encrypted binary log content (the file data).…

Starting in version 8.0.14, MySQL server can encrypt all new binary and relay log files on disk. In order to do so, you just need to enable the new binlog_encryption option (and also ensure that you have a keyring).…

When deciding on your backup strategy, one of the key components for Point In Time Recovery (PITR) will be the binary logs. Thankfully, the mysqlbinlog command allows you to easily take binary log backups, including those that would otherwise be encrypted on disk using encrypt_binlog=ON.

When

mysqlbinlog

  is used with

--raw --read-from-remote-server --stop-never --verify-binlog-checksum

  then it will retrieve binary logs from whichever master it is pointed to, and store …