Storing JSON in a relational database is something developers have done for quite some time. There are a variety of reasons why you would want to store JSON in a database table – user preferences and configuration data are two good examples. The JSON Data Type was introduced to MySQL in version 5.7.8. This data type allows […]

Looking at how people are using COUNT(*) and COUNT(col), it looks like most of them think they are synonyms and just use what they happen to like, while there is a substantial difference in performance and even query results. Also, we find a difference in execution on InnoDB and MyISAM engines.

NOTE: All tests were applied for MySQL version 8.0.30, and in the background, I ran every query three to five times to make sure that all of them were fully cached in the buffer pool (for InnoDB) or by the filesystem (for MyISAM).

Count function for Innodb engine:

Let’s have look at the following series of examples for InnoDB engine:

CREATE TABLE count_innodb (
  id int(10) unsigned NOT NULL AUTO_INCREMENT,
  val_with_nulls int(11) default NULL,
  val_no_null int(10) unsigned NOT NULL,
  PRIMARY KEY idx (id)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

(mysql) > select count(*) from count_innodb; …

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If you have data stored in a Microsoft SQL Server database and you want to import it into MySQL HeatWave Database Service in OCI, you can use the procedure described in this article.

There are several ways you can try to speed up a MySQL replica. Here are some ideas:

When performing physical backup on system that are heavily used, it can happen that the backup speed cannot keep up with the redo log generation. This can happen when the backup storage is slower than the redo log storage media and this can lead in inconsistency in the generated backup. MySQL Enterprise Backup (aka MEB) […]

What is MySQL InnoDB Redo Log Archiving ? How does it work ? Discover this important MySQL InnoDB feature reading this blog post.

In this article we will see how to perform a live migration from Azure/MySQL to OCI/MySQL HeatWave. As Azure allows public connections directly to the database, this is what I will use to migrate and replicate the data between both clouds. Also, since this content is focused on data migration, I won’t explore all the […]

Live Migration from Azure Database for MySQL to MySQL HeatWave Database Service on Oracle Cloud (OCI)

Recently, I wrote several articles on how to load data from CSV files to migrate from different databases to MySQL Database Service: We saw that the most complicate is to write the CREATE TABLE statement that matches the data. I also received some questions about how to generate the table’s definition when only the CSV […]