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Displaying posts with tag: 8.0 (reset)
Fun with Bugs #73 - On MySQL Bug Reports I am Subscribed to, Part X

It's time to continue my review of MySQL bug reports that I considered interesting for some reason recently. I had not got any notable reaction from Oracle engineers to my previous post about recent regression bugs in MySQL 8.0.13, so probably this topic is not really that hot. In this boring post I'll just review some bugs I've subscribed to since August that are still not closed, starting from the oldest.

Let me start with a couple of bug reports that remain "Open":

  • Bug #91959 - "UBSAN: signed integer overflow in lock_update_trx_age". It's really unusual to see bug reported by …
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MySQL InnoDB Cluster with 2 Data Centers for Disaster Recovery: howto

As you know, MySQL InnoDB Cluster is a High Availability solution for MySQL. However more and more people are trying to use it as a Disaster Recovery solution with 2 data centers. Natively, this is not yet supported. But it’s already possible to realize such setup if we agree with the following points:

  •  a human interaction is required in case of Disaster Recovery which, by my own experience, is often acceptable
  • a human interaction is required if the any Primary-Master acting as asynchronous slave leaves its group  (crash, network problem, …) or becomes secondary

These are not big constraints and it’s relatively easily to deal with them.

The Architecture

The situation is as follow:

  • 2 data centers (one active, one inactive, only used for disaster recovery)
  • 2 MySQL InnoDB Clusters (one in each DC)
  • 3 members in each …
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MySQL Memory Consumption and Open Prepare Statements

Today I read the nice post of Bhuvanesh on the memory leak issue they experienced with MySQL. In fact when you read the post, you realize that MySQL was just following the parameters that were setup (the default of max_prepare_stmt_count is 16382 even on 5.6).

I’m still convinced that the problem should be resolved in the application even if the use of ProxySQL for multiplexing is great.

In MySQL 8.0, we have enabled the …

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MySQL: when will the password of my users expire ?

Has you may already know, in MySQL it is possible to set an expiration period for passwords.

It’s not always obvious to see when the password will expire. And most of the time if you don’t pay much attention you will get something like this:

ERROR 1820 (HY000): You must reset your password using
ALTER USER statement before executing this statement.

Let me share you a small query that check for how long your password is still valid in case it was created with an expiration delay or if the global default_password_lifetime is set on …

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Innotop for MySQL 8.0

Recently, I did some maintenance on Innotop and I merged several pull requests including one to support MySQL 8.0 (thank you yoku0825 for the contribution).

As you know, Innotop is written in Perl and to be able to use it with MySQL 8.0, you need to have Perl DBD for MySQL compatible with MySQL 8.0 too (a driver that support the new default authentication plugin, caching_sha2_password).

If you are using Fedora 29, I created such package and you can download it here: …

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On Some Recent MySQL Optimizer Bugs

Yet another topic I missed in my blog post on problematic MySQL features back in July is MySQL optimizer. Unlike with XA transactions, it was done in purpose, as known bugs, limitations and deficiencies of MySQL optimizer is a topic for a series of blog posts if not a separate blog. At the moment the list of known active bug reports in optimize category consists of …

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On MySQL XA Transactions

One of the features I missed in my blog post on problematic MySQL features back in July is XA transactions. Probably I was too much in a hurry, as this feature is known to be somewhat buggy, limited and not widely used outside of Java applications. My first related feature request, Bug #40445 - "Provide C functions library implementing X/OPEN XA interface for Bea Tuxedo", was created almost 10 years ago, based on the issue from one of MySQL/Sun customers of that time. I remember some …

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Master-Slave Replication with MySQL 8.0 in 2 mins

There are multiple way to setup replication with MySQL 8.0 and our replication offer as never been so rich: asynchronous, semi-synchronous, group replication, multi-source, … and much more options !

But if you want to setup a very quick Master-Slave environment from scratch for a quick test (you can always use dbdeployer), here are some commands to make it right the first time

Requirements

You need to have MySQL 8.0 installed and running on both servers and with the same initial data (a fresh install for example). Here we use mysql1 and mysql2. We will also use GTID as it’s much more convenient.

Servers Configuration

Let’s setup mysql1 first:

mysql1> SET PERSIST server_id=1; 
mysql1> SET …
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MySQL and Memory: a love story (part 2)

We saw in the previous post that MySQL likes memory. We also saw how to perform operating system checks and some configuration changes for Swap and NUMA.

Today, we will check what MySQL server can tell us about its memory usage.

Introduced in MySQL 5.7 and enabled by default in MySQL 8.0, the Performance_Schema‘s Memory instrumentation allows us to have a better overview of what MySQL is allocating and why.

Let’s check on our MySQL server using SYS:

Pay attention that there is a bug related to how InnoDB Buffer Pool statistics are accounted in Performance_Schema. This is fixed in 8.0.13. …

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On MySQL Replication Bugs

While writing about problematic Oracle MySQL features previously I concentrated mostly on InnoDB problems that I have to fight with really often and deliberately skipped replication from even the preliminary list of features to study in details for that blog post. First of all, I mostly work with MariaDB users now, and implementation of many replication features in MariaDB is notably different already (and has its own list of known problems). But this happened also because (asynchronous) replication plays a key role in most MySQL environments and deserves a detailed study in a separate post.

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