Introduction In this article, we are going to test the MySQL 8 implementation of custom SQL CHECK constraints. Although the CHECK clause is a standard SQL feature, prior to MySQL 8.0.16, the clause was parsed and ignored, so this functionality could only be emulated via BEFORE INSERT and UPDATE triggers. Custom SQL CHECK constraints As I explained in this article, custom SQL CHECK constraints are very useful to ensure non-nullability constraints for JPA entity subclass-specific attributes when using the SINGLE TABLE JPA inheritance strategy. To understand the problem, consider we have the... Read More
Since 8.0.16, MySQL Server supports a --validate-config option
that enables the startup configuration to be checked for problems
without running the server in normal operational mode.
--validate-config can be used any time, but is particularly useful after an upgrade, to check whether any options previously used with the older server are considered by the upgraded server to be deprecated or obsolete.
MySQL (really) supports CHECK CONSTRAINT since version 8.0.16. In this article I will show you 2 things: - An elegant way to simulate check constraint in MySQL 5.7 & 8.0. - How easy & convenient it is to use CHECK constraints in 8.0.16.
MariaDB 10.2 includes some long-awaited features. In this blog, we are going to discuss the improvements to some table definitions: the DEFAULT clause and the CHECK constraints. These clauses describe columns default values and rules for data validation.
Note that MariaDB 10.2 is still in alpha stage. This article describes the current state of these features, which could change before MariaDB 10.2 becomes GA.
The DEFAULT clause
The DEFAULT clause has always been supported in MariaDB/MySQL, but traditionally it only accepted literal values (like “hello world” or “2”). MariaDB 10.2 removes this limitation, so DEFAULT can now accept most SQL expressions. For example:
- fiscal_year …
It felt like the right time for us to look back at some useful commands for table maintenance that some of us may not have mastered as much as we might like to think.
In my post about gathering index statistics, I referred to
ANALYZE TABLE, and
REPAIR TABLE — but I never explained in depth what
the different commands do, and what the differences between them
are. That is what I thought I would do with this post, focusing
on InnoDB and MyISAM, and the differences in how they treat those
commands. I will also look at different cases and see which one
is right for in each case.