The problem

In PXC 5.6 and 5.7, when using xtrabackup-v2 as the SST method, the DBA must create a user with the appropriate privileges for use by Percona XtraBackup (PXB). The username and password of this backup user are specified in the wsrep_sst_auth variable.

This is a problem because this username and password was being stored in plaintext and required that the configuration file be secured.

The PXC 8.0 solution

(This feature is still under development and may change before PXC 8.0 GA)

Because the wsrep_sst_auth is only needed on the donor side to take a backup, PXC 8.0 uses an internal user (created specifically for use by PXC) with a randomly generated password. Since this user is only needed on the donor, the plaintext password is not needed on the joiner …

SQL LTRIM Function Example is today’s topic. SQL LTRIM function is used for removing all the leading whitespaces or specified characters from the string, i.e. from the left-hand side of the string. In this tutorial, you will learn how to use a MySQL and SQL Server LTRIM() function to remove leading blanks from a string. Oracle/PLSQL LTRIM function removes all specified characters from the left-hand side of a string.

SQL LTRIM Function

The LTRIM() function returns the string after removing leading blanks.

The following shows the syntax of the LTRIM() function.

SELECT LTRIM (input_string, [trim_string])

PARAMETERS

Input_string: It is the string from where the characters have to be removed from the left-hand side.

Trim_string: It is completely optional. It is mainly used for specifying the characters to be removed. If this parameter is omitted, then …

MySQL to ClickHouse Replication 

MySQL works great for Online Transaction Processing (OLTP) systems, MySQL performance degrades with analytical queries on very large database infrastructure, I agree you can optimize MySQL query performance with InnoDB compressions but why then combine OLTP and OLAP (Online Analytics Processing Systems) when you have columnar stores which can deliver high performance analytical queries more efficiently? I have seen several companies building dedicated MySQL servers for Analytics but over the period of time they end spending more money in fine tuning MySQL for Analytics with no significant improvements, There is no point in blaming MySQL for what it is not built for, MySQL / MariaDB is any day a bad choice for columnar analytics / big data solutions.  Columnar database systems are best suited for handling large quantities of data: data stored in columns typically is easier to compress, it is …

At Shopify, we run a large fleet of MySQL servers, with numerous replica-sets (internally known as “shards”) spread across three Google Cloud Platform (GCP) regions. Given the petabyte scale size and criticality of data, we need a robust and efficient backup and restore solution. We drastically reduced our Recovery Time Objective (RTO) to under 30 minutes by redesigning our tooling to use disk-based snapshots, and we want to share how it was done.

Challenges with Existing Tools

For several years, we backed up our MySQL data using Percona’s Xtrabackup utility, stored its output in files, and archived them on Google Cloud Storage (GCS). While pretty robust, it provided a significant challenge when backing up and restoring data. The …

Percona is happy to announce the first experimental binary of Percona XtraDB Cluster 8.0 on October 1, 2019. This is a major step for tuning Percona XtraDB Cluster to be more cloud- and user-friendly. This release combines the updated and feature-rich Galera 4, with substantial improvements made by our development team.

Improvements and New Features

Galera 4, included in Percona XtraDB Cluster 8.0, has many new features. Here is a list of the most essential improvements:

• Streaming replication supports large transactions
• The synchronization functions allow action coordination (wsrep_last_seen_gtid, wsrep_last_written_gtid, wsrep_sync_wait_upto_gtid)
• More granular and improved error logging. wsrep_debug is now a multi-valued variable to assist in controlling the logging, and logging messages have been significantly improved.
…

Lower() Function Example In MySQL and SQL Server is today’s topic. The SQL LOWER function converts all the characters in a string into lowercase. If you want to convert all characters in a string into uppercase, you should use the UPPER function. SQL LOWER function is used for lowering the case of a string, i.e. all the characters in the specified string will be converted to lower case. This is one of the String functions.

SQL LOWER Function

See the following syntax.

SELECT LOWER (input_string)

PARAMETERS:

Input_string: It is the string whose characters are to be converted to lowercase. The input string can be any string or any table column.

NOTE:

If any number …

MySQL Galera Cluster 4.0 is the new kid on the database block with very interesting new features. Currently it is available only as a part of MariaDB 10.4 but in the future it will work as well with MySQL 5.6, 5.7 and 8.0. In this blog post we would like to go over some of the new features that came along with Galera Cluster 4.0.

Galera Cluster Streaming Replication

The most important new feature in this release is streaming replication. So far the certification process for the Galera …

SQL Left Function Example | LEFT() In SQL Server And MySQL is today’s topic. LEFT FUNCTION in SQL is used for extracting a substring starting from the left, followed by the number of characters. The LEFT() function extracts several characters from the string (starting from left).

SQL Left Function

The LEFT() function extracts a given number of characters from the left side of a supplied string.

The syntax of the LEFT() function is as follows.

SELECT LEFT (string, no_of_characters);

See the following parameters.

PARAMETERS:

1. String: An input string from which the substring will be extracted and can be a literal string, variable or a column.
2. No_of_characters: Number of characters you wish to extract from the string.

The LEFT() function returns a value of VARCHAR when …

Overview

Clustering provides high availability and disaster recovery, along with the ability to read-scale both locally and globally. Some clusters even provide active/active capabilities, which others have a single master.

Real time database replication is a must for clustering and other key business purposes, like reporting. There are a number of replication technologies available for MySQL, and some are even bundled into various solutions. When choosing a replication methodology, it is paramount to understand just how the data moves from source to target. In this blog post, we will examine how asynchronous, synchronous, and “semi-synchronous” replication behave when used for clustering. Also, we will explore how …

MySQL has had an interesting optimization for years now1, which has popped up from time to time: in certain circumstances, it may choose to use an index that is index-wise less efficient, but provides the resulting rows in order, to avoid a filesort of the result.

What does this typically look like in production? A query that seems simple and easy takes much longer than it should, sometimes. (Perhaps in production, the query gets killed by pt-kill or exceeds the max_execution_time provided.) The query could be very simple indeed:

SELECT ... WHERE `other_id` = 555 ORDER BY `id` ASC LIMIT 1

There’s an index on other_id, and running the query with an appropriate USE INDEX, the query is fast. Even weirder, changing the query to use LIMIT 10 causes it to …