Rewriting a MySQL query for performance is an important process that every DBA should be aware of so they can fix the wrong queries on runtime without code changes on the application end. ProxySQL has great support for rewriting the queries, which Alkin Tezuysal already explored in his excellent blog ProxySQL Query Rewrite Use Case.

So far, MySQL community provides two built-in query rewrite plugins to perform this task. Recently they introduced the plugin “ddl_rewriter”.

• query rewriter plugin : It has support for INSERT / UPDATE / DELETE / REPLACE statements from MySQL 8.0.12. 
• ddl_rewritter plugin: It supports the CREATE TABLE statement. Introduced at MySQL 8.0.16.

In this blog, I am going to explain the complete process of the implementation and the …

At the Percona engineering team, we often receive requests to analyze changes in MySQL/Percona Server for MySQL behavior from one version to another, either due to regression or a bug fix (when having to point out to a customer that commit X has fixed their issue and upgrading to a version including that fix will solve their problem).

In this blog post, we will analyze the approach used to fix PS-7019 – Correct query results for LEFT JOIN with GROUP BY.

Each release comes with a lot of changes. For example, the difference between MySQL 8.0.19 to 8.0.20:

git diff mysql-8.0.19..mysql-8.0.20 | wc -l
737454
git diff mysql-8.0.19..mysql-8.0.20 --name-only | wc -l
4495

737K lines in 4495 files have changed from one minor version to another.

git …

MySQL Shell 8.0.21 comes with two utilities which can be used to perform logical dumps of all the schemas from an instance (util.dumpInstance()) or selected schemas (util.dumpSchemas()). These tools offer major performance improvements over the mysqldump utility, some of our benchmarks show a throughput up to 3GB/s!…

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Recently I had the opportunity to test a storage device from ScaleFlux called CSD 2000. In this blog post, I will share the results of using it to run MySQL in comparison with an Intel device that had a similar capacity.

First of all, why do we need another storage device? Why is ScaleFlux any different?

The answer is simple; it gives us built-in compression and atomic writes. For many workloads, but especially for database-type workloads, these are very important features.

Because of built-in compression, we can store more data on the ScaleFlux device than on a similar device with the same capacity.

Because of atomic writes, we can disable InnoDB Double Write buffer which means less writes/fsync on the disk layer. This should give us a performance advantage against non-atomic drives.

I ran many different tests on different data sizes, with different …

Undo Tablespaces can be truncated either implicitly or explicitly in MySQL 8.0. Both methods use the same mechanism. This mechanism could cause periodic stalls on very busy systems while an undo tablespace truncate completes. This problem has been fixed in MySQL 8.0.21.…

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So you have waited two weeks (cause the crash isn’t easily repeatable) and finally you get the crash again. You check your non-datadir core file directory with loads of free space and discover nothing was written. When MySQL crashes, you … Continue reading →

We all know as SQL professionals that a common use of the ALTER TABLE command is that we can change a tables’ structure in a myriad number of ways. And, that’s a good thing too because chances are, you won’t always nail down the initial structure. Due to changing business or application requirements, you may even have to add additional columns that were not considered during the schema design phase. Suppose you have many tables that are structured similarly and they all need a specific column added to their already-existing design. Under certain circumstances, using the MySQL Shell in Python mode (\py), can reduce the number of manual ALTER TABLE statements you have to type. Continue reading to see examples in the MySQL Shell…

Photo by elCarito …

Introduced in MySQL Shell 8.0.21, the new MySQL Shell Dump and Load utilities has as its main goal to minimize the time needed to create and restore logical dumps of large data sets.

Through heavy parallelization and other techniques, we were able to reduce the time needed for these tasks by an order of magnitude compared to previous dump utilities.…

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This second part about the new MySQL Shell Dump & Load utilities aims to demonstrate the performance while also comparing it with various other logical dump and load tools available: mysqldump, mysqlpump & mydumper.

To make the numbers more meaningful, I used several real world production datasets that are available online: stackoverflow.com…

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MySQL Shell 8.0.21 includes some exciting new utilities to create a logical dump and do a logical restore, with a focus on ease of use, performance and integration. In MySQL Shell 8.0.17, we already introduced a multi-threaded CSV import utility util.importTable()…

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