We recently migrated some of EverSQL's workload from AWS RDS MySQL to Aurora MySQL. In this post I'll share several options I explored, and the issues I ran into when using each of them, and specifically AWS DMS, so hopefully you could avoid similar issues when going through the migration process.

Potential solutions for migrating RDS MySQL to Aurora MySQL

Naturally, I first started with AWS's documentation, which states you can migrate RDS MySQL to Aurora MySQL by creating an Aurora read replicate and promoting it after replication is done. Unfortunately, that solution wasn't viable in our case, as the RDS instance was already upgraded to MySQL 8.0.28, while Aurora MySQL only supports …

Question on the Libera/#mysql IRC channel:

Is there a way to split a simple select into multiple returned rows? For example, select 1, 2, 3 to be returned as rows?

This is actually asking for a table literal notation. I know of four ways to construct a table literal in MySQL:

UNION ALL

The oldest way to construct a table literal in any SQL that supports UNION is the UNION ALL construct. Write SELECT statements to return literal rows, and add them together to a table using UNION ALL:

mysql> select i from (
    ->   select 1 as i union all
    ->   select 2 as i union all
    ->   select 3 as i
    -> ) as t;
+---+
| i |
+---+
| 1 |
| 2 |
| 3 |
+---+
3 rows in set (0.00 sec)

This has always worked, even on the oldest versions …

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The title is not entirely true, but ‘FTWRL on MyDumper is not needed anymore for consistent backups’ was a long title. One more time, I wanted to share a new feature in MyDumper. This is related to an important piece: the locking mechanism that mydumper uses to sync all the threads.

MyDumper was born because, at that time, we didn’t have a tool that could take a consistent logical backup using multiple threads. Syncing all the threads was one of the problems, which has been solved using FLUSH TABLE WITH READ LOCK (FTWRL), til all the threads execute START TRANSACTION WITH CONSISTENT SNAPSHOT (STWCS), then we release the FTWRL and all the threads are in sync. We all know that FTWRL is very expensive and difficult to acquire on some database workloads.

I started to think about alternatives to avoid using FTWRL, and my first thought was, why …

One of the questions I am often asked is in what cases I would prefer MyRocks over InnoDB. We have covered MyRocks in our blog previously:

MyRocks Performance – Percona Database Performance Blog

Saving With MyRocks in The Cloud – Percona Database Performance Blog

But it would be good to refresh some materials.

This time I want to take an interesting (and real) data set, which I also covered previously: the Reddit Comments dataset (see Big Dataset: All Reddit Comments – Analyzing with ClickHouse – Percona Database Performance Blog). The dataset is still available for download from …

While equality and inequality filter conditions are very common, many times you wish to filter the FROM clause table rows based on values that are less than or greater than another value. MySQL (and SQL in general) supports the less than (<) and greater than (>) operators. Continue reading and see examples of each…

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Azure Database for MySQL

Introduction

This second blog follows the first blog about deploying MySQL Server on Microsoft Azure. In the first blog, we saw how easy it is to deploy a MySQL server in minutes on the Azure cloud and we connected on it through the MySQL Shell client.

This second blog is more focused on the performance of MySQL in the Azure Cloud. Although I didn’t do any tuning of MySQL parameters, we will see the influence of MySQL Server localization on the latency as well as changes in parameters such as CPU, memory or IOPS on performances using the SysBench tool.

SysBench stress test

Of course there are many tools available to do stress tests. On my side, I decided to use SysBench simply because I know this wonderful free tool and because it is widely deployed. …

The uuid() function in MySQL returns a 36 character hex string, formatted as:

aa479ea9-1d9d-11ed-ba03-564760fe47b7

ColdFusion's createUUID() function returns a 35 character hex string formatted as:

AA479EA9-1D9D-11ED-BA03564760FE47B7

Both store the same amount of data (16 bytes), the only difference is that there is an extra dash in the MySQL uuid() function result.

Here's some SQL I came up with to create a UUID using ColdFusion's formatting in raw SQL:

SELECT upper(concat(left(uuid(), 23), right(uuid(), 12)))

It is not an ideal solution because I am actually calling uuid() twice, but it is sufficient for my use case. You could probably use a regex to remove the extra dash and avoid calling uuid twice if you wanted to try and optimize it. Feel free to post a comment if you can come up with a better way to do it.

Now suppose you want …

During my summer holidays, we released MySQL 8.0.30.

MySQL 8.0.30 was released on July 26th 2022. If you are using 8.0.29, it’s highly recommended to upgrade as there was a bug corrupting InnoDB files in a rare and specific case.

This new release contains several contributions from our awesome Community and on behalf of the entire MySQL Team, as usual, I would like to thanks all our contributors !

This new release contains patches from Facebook/Meta, Marcelo Altmann (Percona), Mengchu Shi, Zhou Xinjing (Tencent), Yuxiang Jiang (Tencent), Namrata Bhave, Hongyuan Li, Alexey Kopytov, Wei Zhao, Piotr Jurkiewicz, Dennis Gao, Zheng Lai, Bin Wang, Hao Wu (Tencent), Weijie Wu and Rahul Malik (Percona).

Once again, thank you all for your great contributions and to the companies you are working for.

…

Welcome back to another issue of OpenLampTech, your source for original and curated MySQL, PHP, and LAMP stack content. We have another packed issue this week. Thanks for reading!

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In OpenLampTech issue #39 we are looking at articles covering:

• PHP traits
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• PHP local development tools
• And much much more.

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