Can we consider the Wordpress database a relational database? Some tables are related to each other, but it doesn't work with foreign keys. So, is it a relational database??

Can we consider the Wordpress database a relational database? Some tables are related to each other, but it doesn't work with foreign keys. So, is it a relational database??

• database

• There is no "WordPress database". WordPress does use MySQL or MariaDB, which are relational databases. – fuxia ♦ Commented Aug 31, 2019 at 21:18
• 1 @fuxia I mean the structure of the database in Wordpress. – Rowayda Khayri Commented Aug 31, 2019 at 21:28

2 Answers 2

The data within the database has functionals relationships. For example, user_meta and user. In that regard, it would be considered relational data.

On the other hand, if you mean, that referential integrity is strictly enforced, no it is not. This is mostly a product of MyISAM which is faster but does not support foreign key checks. On the whole, with projects such as WordPress, a simple index of fields used in WHERE clauses more than suffice.

This is often the same as most projects that use MySQL - the table relationships are implied through naming but enforced at the logic layer, not the data layer. This is because only WordPress is expected to read the database and nothing else. Therefore there is no reason to put data and key services into action (which is the design rationale behind MyISAM (as far as I understand).

If you were to dig intot the core of WordPress, you would find WHERE clauses and even joins which expect there to be a relationship between data in one table and data in another. Comments would not work if the individual comments could not be tracked back to the post they were made on. Which is why comments and posts are considered related.

TL;DR: Yes but the key relationships are not enforced due to design considerations.

As to if WordPress covers the requirements of, say, third normal form, that's a whole other debate.

Foreign key constraints cannot be used with MyISAM tables. InnoDB tables support them. You can change all MyISAM tables to InnoDB tables with the following code:

function changeAllMyIsamToInnoDB() {
    global $wpdb;

    $sql = "SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES
        WHERE TABLE_SCHEMA = 'your-database-name' 
        AND ENGINE = 'MyISAM'";

    $rs = $wpdb->get_results($sql);

    foreach ($rs as $row) {
        $tbl = $row->TABLE_NAME;
        $sql = "ALTER TABLE `$tbl` ENGINE=INNODB";
        $wpdb->query($sql);
    }
}
changeAllMyIsamToInnoDB();

Do your database backup, first!

Insert the above code into functions.php of your current theme, replacing your-database-name with the name of your database.

Remove the code after the change is done.