This is a 3 part blog series:

• Part 1: The SYSTEM_USER Dynamic Privilege
• Part 2 : Partial Revokes from Database Objects
• Part 3 : How to create multiple accounts for an app?

You can now grant CREATE USER so that your web apps would be able to use multiple accounts without you risking the end user hijacking the database by changing your root credentials for example.  …

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Percona is glad to announce the release of Percona XtraBackup 2.4.14 on May 1, 2019. You can download it from our download site and apt and yum repositories.

Percona XtraBackup enables MySQL backups without blocking user queries, making it ideal for companies with large data sets and mission-critical applications that cannot tolerate long periods of downtime. Offered free as an open source solution, it …

In this research,  I wanted to see what kind of performance improvements could be gained by using a ClickHouse data source rather than PostgreSQL. Assuming that I would see performance advantages with using ClickHouse, would those advantages be retained if I access ClickHouse from within postgres using a foreign data wrapper (FDW)? The FDW in question is clickhousedb_fdw – an open source project from Percona!

The database environments under scrutiny are PostgreSQL v11, clickhousedb_fdw and a ClickHouse database. Ultimately, from within PostgreSQL v11, we are going to issue various SQL queries routed through our clickhousedb_fdw to the ClickHouse database. Then we’ll see how the FDW performance compares with those same queries executed in native PostgreSQL and native ClickHouse.

Clickhouse Database

ClickHouse is an open source column based database management system which can achieve performance of between 100 and …

War story of the day: do not use — or be very careful when using — the max_connections beta database flag on CloudSQL... because it has many bugs.

I was hit by this today: we set the max_connections flag to 8000 on a primary server a few days ago, we had a failover last night, and the flag was not set on the replica (bug #1).

Update 2019-05-03: there is another bug (bug #1.5).  If you set the

Last week, Oracle reported on the list of MySQL Community Contributors for 2019 and we’re proud to say that five serving Perconians made it to the list of 19 people recognized as such. Entries are nominated by the MySQL community and their nominations are assessed against six criteria by a volunteer committee of community mavens.

1. The most active code contributor
2. Bug reporter
3. The most active MySQL blogger
4. People who plays very active role in translation/documentation of MySQL articles
5. People who provides feedback on DMR releases, Labs releases, or change proposals
6. Anyone in the community who worked their butt off or did really useful work that you feel should be thanked publicly

The members of Percona who will be proudly wearing their community …

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MySQL 8.0.16 was released last week and includes many great features including support for CHECK constraints and upgrades without the need of mysql_upgrade. As usual there are also several contributions from the community. These are the ones, I would like to highlight in this blog to say “thank you for the contributions”.

Facebook has contributed with another two patches and so has Daniel Black. Additionally, there are patches from Yuhui Wang, Wei Zhao, Yan Huang, and Dirkjan Bussink. The contributions are:

• mysql-test-run.pl now supports the MTR_UNIQUE_IDS_DIR environment variable, which may be set to specify a unique-IDs directory to be used as the common location …

Join Percona CEO Peter Zaitsev and PingCAP Senior Product and Community Manager Morgan Tocker as they present How to horizontally scale MySQL with TiDB while avoiding sharding issues on Wednesday, May 1st, 2019, at 11:00 AM PDT (UTC-7) / 2:00 PM EDT (UTC-4).

Register Now

In this joint webinar, PingCAP will provide an introduction and overview of TiDB, tailored for those with a strong background in MySQL. PingCAP will use MySQL as an example to explain …

(In the previous post, Part 1, we covered Data Writing.)

In this blog post, we continue on our series of exploring MyRocks mechanics by looking at configurable server variables and column family options. In our last post, I explained at a high level how data first entered memory space and in this post, we’re going to pick up where we left off and talk about how the flush from immutable memtable to disk occurs. We’re also going to talk about how newly created secondary indexes on existing tables get written to disk.

We already know from our previous post in the series that a flush can be prompted by one of several events, the most common of which would be when an active memtable is filled to its maximum capacity and is rotated into immutable status.

When your immutable memtable(s) is ready …

This post is just a reminder on how to find which settings have been set on MySQL Server.

If you have modified some settings from a configuration file or during runtime (persisted or not), these two queries will show you what are the values and how they were set. Even if the value is the same as the default (COMPILED) in MySQL, if you have set it somewhere you will be able to see where you did it.

Global Variables

First, let’s list all the GLOBAL variables that we have configured in our server:

SELECT t1.VARIABLE_NAME, VARIABLE_VALUE, VARIABLE_SOURCE
FROM performance_schema.variables_info t1
JOIN performance_schema.global_variables t2
ON t2.VARIABLE_NAME=t1.VARIABLE_NAME
WHERE t1.VARIABLE_SOURCE != 'COMPILED';

This is an example of the output:

Session Variables

And now the same query for the session variables:

SELECT t1.VARIABLE_NAME, VARIABLE_VALUE, …

As of 8.0.16, the mysql_upgrade binary is deprecated, but its functionality is moved into the server. Let’s call this functionality the “server upgrade”. This is added alongside the Data Dictionary upgrade (DD Upgrade), which is a process to update the data dictionary table definitions.…

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