I am always surprised to learn something new whenever I talk to a member of the open-source community. No matter how much I think I have heard of every use case there is for Liquibase (and database change management in general), I always hear something that makes this space still feel new. There’s always something left to discover.

Today, that new something is the problem of how to perform large batches of changes with SQL ALTER TABLE statements. No problem you say? Okay, but this ALTER needs to happen in production. Still not worried? Well, let’s say you have millions of rows, and because you’re so successful, you have many transactions happening per minute (maybe even per second). Yeah…now we are talking. You can’t alter the table because you can’t afford to lock that table for the …

Earlier this week, Oracle released their Q4 releases series. As on the previous releases, backward compatibility has been broken with previous versions of the server. This time on both MySQL 5.7 and 8.0:

MySQL 5.7.32

While our QA team was performing an extensive test on it,  we found out this version introduced a new compression format version. This change breaks backward compatibility with older versions of MySQL, which is expected on the 8.0 series but is not on 5.7. As Percona XtraBackup (PXB) is based on MySQL code, it makes MySQL 5.7.32 incompatible with current versions of Percona XtraBackup 2.4.20 and prior.

The issue does not affect only Percona XtraBackup but also prevents users from downgrading the server from 5.7.32 to any lower version on the 5.7 series – More details at …

One of the most exciting storage-related features in Kubernetes is Volume snapshot and clone. It allows you to take a snapshot of data volume and later to clone into a new volume, which opens a variety of possibilities like instant backups or testing upgrades. This feature also brings Kubernetes deployments close to cloud providers, which allow you to get volume snapshots with one click.

Word of caution: for the database, it still might be required to apply fsfreeze and FLUSH TABLES WITH READ LOCK or

LOCK BINLOG FOR BACKUP

.

It is much easier in MySQL 8 now, because as with atomic DDL, MySQL 8 should provide crash-safe consistent snapshots without additional locking.

Let’s review how we can use this feature with Google Cloud Kubernetes Engine and …

Google Cloud Platform (GCP), with its CloudSQL offering, has become a leading platform for database-as-a-service workload deployments for many organizations. Scale and High Availability have surfaced as primary goals for many of these deployments. Unfortunately, the attainment of these objectives has been challenging.

Often, the answer has been to simply add more CloudSQL databases. Many, however, have found a better solution in Percona’s fully managed MySQL environment based in Google’s GCE. Percona’s fully managed MySQL offering provides benefits similar to CloudSQL, plus the ability to run MySQL with an unlimited number of tables and much more reliable database availability. This has empowered these organizations to reclaim control over their architecture decisions. With Percona’s fully managed MySQL, your database architecture choices are once again based on your needs and the needs of your workload, rather than the capabilities …

Changing the default value (3) of log_error_verbosity in MySQL/Percona Server for MySQL 5.7 can have a hidden unintended effect! What does log_error_verbosity do exactly? As per the documentation:

“The log_error_verbosity system variable specifies the verbosity for handling events intended for the error log.“

Basically a value of 1 logs only [Errors]; 2 is 1)+[Warnings]; and 3 is 2)+[Notes].

For example, one might be tempted to change the default of log_error_verbosity since the error.log might be bloated with thousands (or millions) of lines with [Notes], such as:

2020-10-08T17:02:56.736179Z 3 [Note] Access denied for user 'root'@'localhost' (using password: NO)
2020-10-08T17:04:48.149038Z 4 [Note] Aborted connection 4 to db: 'unconnected' user: 'root' host: 'localhost' (Got timeout reading communication packets)

(P.S. you can read more about those Notes on this other Percona blog posts):

For what reason should I use a real multi-primary setup?

To be clear, not a multi-writer solution where any node can become the active writer in case of needs, as for Percona XtraDB Cluster (PXC) or Percona Server for MySQL using Group_replication. No, we are talking about a multi-primary setup where I can write at the same time on multiple nodes. I want to insist on this “why?”.

After having excluded the possible solutions mentioned above, both covering the famous 99.995% availability, which is 26.30 minutes of downtime in a year, what is left?

Disaster Recovery? Well, that is something I would love to have, but to be a real DR solution we need to put several kilometers (miles for imperial) in the middle.

And we know …

Recently I was dealing with an unexpected issue raised by our Support customer, in which data became inconsistent after a schema change was applied.

After some investigation, it turned out that affected tables had a special word in the comments of some columns, which triggered an already known (and fixed) issue with the TableParser.pm library of Percona Toolkit.  The problem is that the customer was using an outdated Toolkit version, where pt-online-schema-change was using that buggy parser.

This bug applies only to Percona Toolkit versions up to 3.0.10, so if you have already 3.0.11 or newer installed, you can skip the rest of this post as these are no longer affected.

I am writing this post to warn every user of pt-online-schema-change who has not upgraded the toolkit, as …

Visibility is a blessing, and with databases, visibility is a must. That’s true not only for metrics but for the queries themselves. Having info on all the stats around query execution is priceless, and Percona Monitoring and Management (PMM) offers that in the form of the Query Analytics dashboard (QAN).

But where to start? QAN helps you with that by calculating the query profile. What is the profile? It’s a rank of queries, ordered by Load, so it is easy to spot the heaviest queries hitting your database. The Load is defined as the “Average Active Queries” but can also be defined as a mix of Query Execution Time Plus Query count. In other words, all the time the query was alive and kicking.

The Profile in PMM 2.10.0 looks like this:

The purpose of this profile is to facilitate the task of finding the …

Schema changes are the big challenges in Galera replication. So, it is recommended to understand the schema changes operation for everyone who uses the Percona XtraDB Cluster (PXB)/Galera clusters. In this blog, I am going to explain the operation and impact of the various schema changes methods used in the PXB/Galera cluster.

• Schema changes with “wsrep_OSU_method = TOI”
• Schema changes with “wsrep_OSU_method = RSU”
• Schema changes with “ONLINE ALGORITHMS”
• Schema changes with “pt-osc”
• Schema changes with “gh-ost”

For testing:

• I have configured the 3-node Percona Xtradb Cluster (8.0.19).
• Executing read/write load using the sysbench.

mysql> select @@wsrep_cluster_address\G
*************************** 1. row …

Hello everyone, in this little post we will review a new feature in MySQL 8.

What is “CHECK Constraint”?

This is a new feature to specify a condition to check the value before INSERT or UPDATE into a row. The constraint could return an error if the result of a search condition is FALSE for any row of the table (but not if the result is UNKNOWN or TRUE).

This feature starts working on MySQL 8.0.16, and in previous versions, we could create it, but it doesn’t work, meaning the syntax is supported but it is not working,

There are some rules to keep in mind…

– AUTO_INCREMENT columns are not permitted
– Refer to another column in another table is not permitted
– Stored functions and user-defined functions are not permitted (you can not call a function or any user-defined functions)
– Stored procedure and function parameters are not permitted (you cannot call …