The benefits of jemalloc versus glibc memory allocator for use with MySQL have been widely discussed. With jemalloc (along with Transparent Huge Pages disabled) there is less memory fragmentation, and thus more efficient resource management of the server memory. For MySQL 5.6, installing jemalloc is enough to enable it when starting the MySQL process. However, for MySQL 5.7 and 8.0.X series, you will need to take a few extra steps.

Enabling jemalloc on Percona Server for MySQL

Installing the jemalloc package is simple for Percona. This is because the library is available on the Percona repository, which is available for both apt and yum package management:

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If you use SQL on a regular basis, then you are well aware that Window Functions are powerful. They allow us to simplify queries that would otherwise be quite the mess. We can provide meaningful insight across rows of data without collapsing the results into a single value. I have written numerous blog posts on Window Functions, many here recently. I decided to make this blog post a compilation of all the Window Function posts I have written, providing a one-stop source for any readers interested in learning more about Window Functions…

Image by Free-Photos from …

The tables in PERFORMANCE_SCHEMA (P_S) are not actually tables. You should not think of them as tables, even if your SQL works on them. You should not JOIN them, and you should not GROUP or ORDER BY them.

Unlocked memory buffers without indexes

The stuff in P_S has been created with “keep the impact on production small” in mind. That is, from a users point of view, you can think of them as unlocked memory buffers – the values in there change as you look at them, and there are precisely zero stability guarantees.

There are also no indexes.

Unstable comparisons

When sorting a table for a GROUP BY or ORDER BY, it may be necessary to compare the value of one row to other rows multiple times in order to determine where the row goes. The value compared to other rows can change while this happens, and will change more often the more load the server has. The end …

I am pretty new on the Oracle Cloud Infrastructure technology, so maybe I am talking about something you already know. But anyway I prefer to share this case: it can help if you encounter the same problem as me. Let’s take the risk to have too much information rather than nothing!

The problem

I was doing some tests on the new MySQL Database Service and during the setup I decided to generate my ssh keys via the OCI console:

When I tried to connect via PuTTY or MobaXterm to my compute instance using the opc account and my private key (generated previously), I got the following …

I am pretty new on the Oracle Cloud Infrastructure technology, so maybe I am talking about something you already know. But anyway I prefer to share this case: it can help if you encounter the same problem as me. Let’s take the risk to have too much information rather than nothing!

The problem

I was doing some tests on the new MySQL Database Service and during the setup I decided to generate my ssh keys via the OCI console:

When I tried to connect via PuTTY or MobaXterm to my compute instance using the opc account and my private key (generated previously), I got the …

How scheduler and script stand in supporting failover (Percona and Marco example) 

In part one of this series,  I had illustrated how simple scenarios may fail or have problems when using Galera native support inside ProxySQL. In this post, I will repeat the same tests but using the scheduler option and the external script.

The Scheduler

First a brief explanation about the scheduler.

The scheduler inside ProxySQL was created to allow administrators to extend ProxySQL capabilities. The scheduler gives the option to add any kind of script or application and run it at the specified interval of time. The scheduler was also the initial first way we had to deal with Galera/Percona XtraDB Cluster (PXC) node management in case of issues. 

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How native ProxySQL stands in failover support (both v2.0.15 and v2.1.0)

In recent times I have been designing several solutions focused on High Availability and Disaster Recovery. Some of them using Percona Server for MySQL with group replication, some using Percona XtraDB Cluster (PXC). What many of them had in common was the use of ProxySQL for the connection layer. This is because I consider the use of a layer 7 Proxy preferable, given the possible advantages provided in ReadWrite split and SQL filtering. 

The other positive aspect provided by ProxySQL, at least for Group Replication, is the native support which allows us to have a very quick resolution of possible node failures.

ProxySQL has Galera …

We are pleased to announce that you can find MySQL session (in Italian) on RIOS OpenSource Week during Dec 1-4, 2020. See details below:

• Event Name: RIOS OpenSource Week
• Event Date: Dec 1-4, 2020
• URL
• MySQL Session (under Finance Track): "MySQL nel fintech: una storia enterprise" (in Italian)
• Speaker: Vittorio Cioe, the MySQL Sales Consultant for Eastern Europe, CIS, Israel and Turkey
• Session date & time: Dec 3, 2020 @ 11:20 CET

MySQL talk is visible for registered people only, so please feel free to register! 

We are happy to invite you to Open Source Week and our MySQL talk!

On a previous blog post, we saw how to create an account on the Oracle OCI using the Oracle Cloud Free Tier offer and then how to instal MySQL Server on the Compute instance.
Some weeks later, the new MySQL Database Service (MDS) was out and I can show you now how to install and configure it.

We are talking about the MySQL 8.0 Enterprise Edition on the on Oracle Generation 2 Cloud Infrastructure. For the moment it’s only available on some of the data regions (Frankfurt and London for the EMEA zone), but normally others will be activated …

On a previous blog post, we saw how to create an account on the Oracle OCI using the Oracle Cloud Free Tier offer and then how to instal MySQL Server on the Compute instance.
Some weeks later, the new MySQL Database Service (MDS) was out and I can show you now how to install and configure it.

We are talking about the MySQL 8.0 Enterprise Edition on the on Oracle Generation 2 Cloud Infrastructure. For the moment it’s only available on some of the data regions (Frankfurt and London for the EMEA zone), but normally others will be …