As you are probably aware, Red Hat Enterprise Linux 6 (RHEL 6 or EL 6 in short) officially reached “End of Life” (EOL) on 2020-11-30 and is now in the so-called Extended Life Phase, which basically means that Red Hat will no longer provide bug fixes or security fixes.

Even though EL 6 and its compatible derivatives like CentOS 6 had reached EOL some time ago already, we continued providing binary builds for selected MySQL-related products for this platform.

However, this became increasingly difficult, as the MySQL code base continued to evolve and now depends on tools and functionality that are no longer provided by the operating system out of the box. This meant we already had to perform several modifications in order to prepare binary builds for this platform, e.g. installing custom compiler versions or newer versions of various system …

Earlier last week, Oracle released their Q2 releases series. Unlike previous releases, backward compatibility has now been broken with previous versions of MySQL.

MySQL 8.0.29 extended the support for the online DDL algorithm INSTANT. Prior to 8.0.29 only adding columns to the end of the table was supported.

In 8.0.29, this functionality was extended to allow the INSTANT algorithm the ability to add columns in any position of the table as well to drop columns. This new functionality required the redo log version to increase and new redo log types to be added, thus making it incompatible with older versions of the MySQL server and also older versions of Percona Xtrabackup. Please note that an in-place minor version downgrade of …

Oracle released MySQL Server 8.0.29 on April 26th and this is a quick review of the release notes.  I have put my own comments in italics.

So what is in the ’29 release of MySQL Server?  Does it come festooned with new, neat features or is it a big bug-fix bonanza?

The TL;DR

While this server release has some interesting stuff, there is no compelling feature that will necessitate an immediate upgrade.  Read through the release notes to see if anything in there that is a must for you but for most of us, MySQL 8.0.29 does not require an immediate update.  If this was a birthday or holiday present, ’29 is the equivalent of getting a fresh box of dental floss – useful but not thrilling.

The shell is evolving too and the new version for VS Code looks promising.

MySQL Server 8.0.29 UTF8MB3?

The server now makes extensive use of UTF8MB3 (yes 3, not …

In the last quarter of 2021, AWS released Aurora version 3. This new version aligns Aurora with the latest MySQL 8 version, porting many of the advantages MySQL 8 has over previous versions.

While this brings a lot of new interesting features for Aurora, what we are going to cover here is to see how DDLs behave when using the ONLINE option. With a quick comparison with what happens in MySQL 8 standard and with Group Replication.

Tests

All tests were run on an Aurora instance r6g.large with a secondary availability zone. The test was composed of:

        Four connections

• • #1 to perform DDL
  • #2 to perform insert data in the table I am altering
  • #3 to perform insert data on a different table 
  • #4 checking the other node operations

In the Aurora instance, a …

When one is responsible for promoting application development from Dev through the various environments such as QA, UAT, etc., through Production, it is often useful to ensure that configurations in test environments are comparable to the final production environment.  This is especially true with systems where a team of DBAs manage the servers.

Obviously, the difference in performance could be due to differences in hardware, storage, networking, software configuration, etc.  The question is how does one quickly and efficiently find the differences without having to run a lot of different commands and compare the output.  Fortunately, our Percona Toolkit has a couple of utilities that can make this much easier.  When you are tasked with supporting large numbers of servers, efficiency is paramount and this is where the toolkit can really help you!

You can find more information on the Percona Toolkit here: …

As a best practice before dropping a large table in MySQL, pt-archiver can be used to delete all the records in batches. This helps to avoid a situation where your server may get stalled under certain circumstances.

I recently read a comment from a user saying “The pt-archiver is not working as expected! It is skipping the last record, which seems like a bug.”. Let’s examine pt-archiver’s default behavior and understand why the author of this comment believes that pt-archiver is bugged (Spoiler: It’s not!).

But wait, before continuing on busting the blame, let me clarify why to use pt-archiver before dropping large tables.

When we drop a table in MySQL:

• Table data/index (ibd) and definition (frm) files are removed.
• Triggers are removed.
• Table definition cache is updated by removing the table being dropped.
• InnoDB buffer pool is scanned for associated pages to …

Ingress is a resource that is commonly used to expose HTTP(s) services outside of Kubernetes. To have ingress support, you will need an Ingress Controller, which in a nutshell is a proxy. SREs and DevOps love ingress as it provides developers with a self-service to expose their applications. Developers love it as it is simple to use, but at the same time quite flexible.

High-level ingress design looks like this: 

1. Users connect through a single Load Balancer or other Kubernetes service
2. Traffic is routed through Ingress Pod (or Pods for high availability)
   • There are multiple flavors of Ingress Controllers. Some use nginx, some envoy, or other proxies. See a curated list of Ingress Controllers here.
3. Based on HTTP headers traffic is routed …

Abstract:

By diving into the details of our case study, we will explain how incorrect table statistics may lead the optimizer to choose a suboptimal execution plan. We will also go into how MySQL calculates the table statistics and the ways to correct the table statistics to prevent it from happening again.

Case study: Incorrect table statistics lead the optimizer to choose a poor execution plan.

A customer reported a drastic performance degradation of a query while there were no code changes and no configuration changes made. The data in this article has been edited for brevity and modified to mitigate the exposure of confidential information. The case has also been approved for publication by the customer.

We obtained the query execution plan, and got the results as shown below (execution plan #1):

mysql> explain 
-> SELECT count(con.id)          ,
->        MAX(DAYNAME(con.date)) ,
-> …

Last month I performed a review of the Percona Operator for MySQL Server which is still Alpha.  That operator is based on Percona Server for MySQL and uses standard asynchronous replication, with the option to activate semi-synchronous replication to gain higher levels of data consistency between nodes. 

The whole solution is composed as:

Additionally, Orchestrator (https://github.com/openark/orchestrator) is used to manage the topology and the settings to enable on the replica nodes, the semi-synchronous flag if required. While we have not too much to say when using standard Asynchronous replication, I want to write a few words on the needs …

Do you wonder if MySQL tells you the truth about writes to tables that have foreign key constraints? The situation is complex, and getting visibility on what is really happening can be a problem.

I found this issue intriguing and decided to share and highlight some examples.

Query Plan

Let us take this example table:

CREATE TABLE `product` (
  `category` int NOT NULL,
  `id` int NOT NULL,
  `price` decimal(10,0) DEFAULT NULL,
  PRIMARY KEY (`category`,`id`)
) ENGINE=InnoDB;

We want to know how costly an example UPDATE against this table will be:

mysql > EXPLAIN update product set id=id+1 where id=65032158 and category=3741760\G
*************************** 1. row ***************************
           id: 1
  select_type: UPDATE
        table: product
   partitions: NULL
         type: range
possible_keys: PRIMARY
          key: PRIMARY
      key_len: 8
          ref: const,const
         rows: 1 …