In Percona Server for MySQL 8.0.29-21, we added one more patch that helps us to build server code on macOS. To be precise here, we still could do this even before this patch but only partially. Now it is possible to build RocksDB Storage Engine as well.

A word of disclaimer here, at the moment, by macOS we still understand macOS for Intel x86_64 architecture (the most recent ARM versions with Apple M1 / M2 processors are out of the scope of this blog post). Moreover, Percona does not provide …

A few weeks ago, we did a Galera Cluster webinar on Managed Galera Clusters on DigitalOcean.

Some of you may notice that the current version of Galera Manager is 1.6.4, and one of the major fixes we have in there is to support the new API token format of DigitalOcean. DigitalOcean has documented this here: Updated API Tokens new management features: in partnership with GitHub –Secret Scanning, Prefixes, and more! and as a consequence we needed to update to accept new API tokens, or it would fail in deployment. If you’re wondering how to create a …

When we run a SELECT in a replica server and it returns a different result to the one we would have obtained had we queried the source server instead, due to changes in the dataset that have not yet been replicated or synchronized to the replica, we get what is known as a stale read. My colleague Marcelo has blogged about Stale Reads and How to Fix Them before.

The need to avoid stale reads is a constraint that leads people into migrating to Percona XtraDB Cluster (PXC) / Galera Cluster or, more recently, Group Replication. I am focusing on PXC and Galera in this short blog post, which, similar to Group Replication, implements not exactly a synchronous replication model but what is commonly referred to as a …

If you write C applications that need to connect to MySQL, you can use the MySQL C API aka libmysqlclient. The MySQL C API replaces the outdated MySQL-Connector-C.

If you want to use MySQL 8.0 as a Document Store with the X Protocol, you need then to use MySQL Connector/C++ 8.0.

Some have asked how to compile only the MySQL C API.

Compiling only libmysqlclient

As the FAQ stipulates it, it’s not possible to only build the library. However, as mentioned in the documentation, it’s possible to reduce the amount of compiled products with some …

The challenge If you have a large MySQL table and you're trying to add a new column and index it, you may have ran into this error:

Creating index 'Name' required more than 'innodb_online_alter_log_max_size' bytes 
of modification log. Please try again.

So how can you address it?

The solution

By default, recent MySQL versions will execute the ALTER statement with the INPLACE flag (unless it's eligible for INSTANT alter, though that's not always the case). this means that the database is using a temporary log (size of innodb_online_alter_log_max_size) which is by default 128MB in most recent versions, to keep track of DML changes happening during the ALTER command. So if the database is executing an UPDATE/INSERT/DELETE during the ALTER, it will keep track of those changes in the temp file, and then after the ALTER is done, it will apply those changes to the table as well.
So you have several options we can …

The following is a short HOWTO about deployment and use of Benchmark-kit (BMK-kit). The main idea of this kit is to simplify your life in running various MySQL benchmark workloads with less blood and minimal potential errors.

Generally as simple as the following :

$ bash /BMK/sb_exec/sb11-Prepare_50M_8tab-InnoDB.sh 32   # prepare data

$ for users in 1 2 4 8 16 32 64 128 256 512 1024 2048
do   
  # run OLTP_RW for 5min each load level..
  bash /BMK/sb_exec/sb11-OLTP_RW_50M_8tab-uniform-ps-trx.sh $users 300
  sleep 15
done

the latest public online version of the following HOWTO is always available from here : http://dimitrik.free.fr/blog/posts/mysql-perf-bmk-kit.html

UPDATE : May.2021 -- workaround fixes for A1 ARM64 systems

UPDATE : Sep.2021 -- dedicated Sysbench binary for MySQL 8.0 & SSL

UPDATE : Oct.2021 -- …

Is SQL, or Structured Query Language, a programming language? That’s a great question! A question that many answer with emphasis: “No, SQL is not a programming language!” There are some who answer yes; and they usually qualify that answer with something like: “SQL is a programming language designed to communicate with relational databases.”

It strikes me that those saying “yes” are saying that SQL is only a collection of interface methods to read from and write to a database engine. Those saying SQL is not a programming language often qualify that a programming language must have conditional logic and iterative structures, which don’t exist in SQL.

There’s a third group that are fence sitters. They decline to say whether SQL is a programming language, but they also say individuals who only write SQL aren’t programmers. That’s a bit harsh from my perspective.

Before …

This is the second article of the series dedicated to MySQL trending.

As I wrote before, understanding your workload and seeing the evolution of it over time can help anticipating problems and work on solutions before the breakdown.

This article covers MySQL History List Length also known as HLL.

MySQL History List is related to InnoDB Undo Logs. InnoDB is a multi-version storage engine (MVCC). It keeps information about old versions of changed rows to support transactional features such as concurrency and rollback. This information is stored in undo tablespaces in a data structure called a rollback segment.

This means that you can start a transaction and continue to see a consistent snapshot even if the data changed by other transaction. This behavior is related to the …

The binary logging format in MySQL has been ROW by default since MySQL 5.7, yet there are still many users sticking with STATEMENT or MIXED formats for various reasons. In some cases, there is just simple hesitation from changing something that has worked for years on legacy applications. But in others, there may be serious blockers, most typically missing primary keys in badly designed schemas, which would lead to serious performance issues on the replicas.

As a Support Engineer, I can still see quite a few customers using STATEMENT or MIXED formats, even if they are already on MySQL 8.0. In many cases this is OK, but recently I had to deal with a pretty nasty case, where not using ROW format was found to cause the replicas to silently lose data updates, without raising any replication errors! Was it some really …

Codership is pleased to announce a new Generally Available (GA) release of the multi-master Galera Cluster for MySQL 5.7 and 8.0, consisting of MySQL-wsrep 5.7.37 (release notes, download) and MySQL-wsrep 8.0.28 (release notes, download) with Galera replication library 3.37 (release notes, download) implementing wsrep API …