This is an update for MySQL 8 Stored PSM to add the ONLY_FULL_GROUP_BY mode to the global SQL_MODE variable when it’s not set during a session. Here’s the code:

/* Drop procedure conditionally on whether it exists already. */
DROP PROCEDURE IF EXISTS set_full_group_by;

/* Reset delimter to allow semicolons to terminate statements. */
DELIMITER $$

/* Create a procedure to verify and set connection parameter. */
CREATE PROCEDURE set_full_group_by()
  LANGUAGE SQL
  NOT DETERMINISTIC
  SQL SECURITY DEFINER
  COMMENT 'Set connection parameter when not set.'
BEGIN

  /* Check whether full group by is set in the connection and
     if unset, set it in the scope of the connection. */
  IF EXISTS
    (SELECT TRUE
     WHERE NOT REGEXP_LIKE(@@SESSION.SQL_MODE,'ONLY_FULL_GROUP_BY'))
  THEN
    SET @@GLOBAL.SQL_MODE := CONCAT(@@SESSION.sql_mode,',ONLY_FULL_GROUP_BY');
  END IF;
END;
$$

/* Reset the default delimiter. */
DELIMITER ;

You can call the …

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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In OpenLampTech issue #60, we are looking at some fantastic articles covering:

• Laravel Eloquent and Query Builder tips
• Drupal’s updated CKEditor 5
• How Symfony powers Drupal
• Best SQL Editors
• WooCommerce Payment Gateways
• And much more

Want to help OpenLampTech be a success …

Space constraint has been an endless and painstaking process for many of us, especially in systems that have a high number of transactions and data growth exceeding hundreds of GBs in a matter of days. In this blog, I will share a solution to remove this space and remove rows from tables in a few seconds regardless of the size of a table without causing any additional load on the database using table partitions.

The first approach that comes to anyone’s mind for deleting the row is using a DELETE query in SQL. Suppose, one wants to delete rows from a table that are older than one year—the query for such operations would be like this:

DELETE FROM salaries WHERE from_date <DATE_SUB(NOW(),INTERVAL 1 YEAR);

The above query is pretty straightforward but there are a few caveats:

• Server business will grow exponentially and could impact the usual traffic on the server.
• To speed up the above query …

Recently, we performed a database engine major version upgrade in one of our customers’ environments from MySQL 5.7.26 to 8.0.27. After this version upgrade, we experienced issues with backups and replication for one of the nodes.

In this article, I will explain these issues in detail and recommend a way to take backups from a replication environment.

To begin with, we upgraded all the database nodes from 5.7.26 to 8.0.27 and as a recommended way we have a backup set-up from one of the replica nodes. Physical backups are being taken using Percona XtraBackup (PXB) so it does not lock the database during the backup.

With MySQL 5.7, a backup was taken using PXB 2.4. Due to the new data dictionaries, redo log and undo log in MySQL 8.0, we also upgraded PXB to 8.0.27 to avoid …

In Managed Services, we have many customers, and as each has a different kind of config and environment, working on their environment is always fun and interesting. In this blog post, I will showcase an issue we faced when dropping a table and how it was resolved.

There was a ticket to drop a table in a client’s production environment (MySQL 5.7). The table had a # symbol at the beginning of the table’s name. I thought it was easy that we can use quotes or backtick symbols to specify the table to drop. But it did not work as I expected and I came to know why the customer created the ticket to drop the table.

The following example recreates the problem. It shows the table, but you are unable to see the structure and cannot drop it.

mysql> show tables;
+--------------------------+
| Tables_in_percona        |
+--------------------------+
| …

Let’s examine COMMIT latency on Aurora v2 (MySQL 5.7) vs. Aurora v3 (MySQL 8.0) vs. RDS MySQL 8.0 2-AZ vs. RDS MySQL 8.0 3-AZ “cluster”.

Let’s examine COMMIT latency on Aurora v2 (MySQL 5.7) vs. Aurora v3 (MySQL 8.0) vs. RDS MySQL 8.0 2-AZ vs. RDS MySQL 8.0 3-AZ “cluster”.

Let’s examine COMMIT latency on Aurora v2 (MySQL 5.7) vs. Aurora v3 (MySQL 8.0) vs. RDS MySQL 8.0 2-AZ vs. RDS MySQL 8.0 3-AZ “cluster”.

In MySQL, the ORDER BY clause is used to sort the records fetched by the SELECT statement, in ascending or descending order. And while the usage of this command is simple in basic cases, there are more complex scenarios requiring much more attention. This article will explore the essence, the syntax, and the usage scenarios […]

The post MySQL ORDER BY Clause: Syntax and 13 Examples appeared first on Devart Blog.