Introduction Ever wanted to connect to a relational database using Java and didn’t know which JDBC Driver Maven dependency to use? If so, this article is surely going to help you from now on. Oracle Since September 2019, the Oracle JDBC Driver is available on Maven Central. For JDK 10 and 11, use the following Maven dependency: For JDK 8, use the ojdbc8 artifact instead: For more details about the proper version to use, check out the following Maven Central link. MySQL The MySQL Driver is available on Maven Central, so just... Read More

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There is an interesting feature in MySQL 5.7+: the global variable super_read_only.  MySQL 5.6 and before only had the read_only global variable which is not preventing a user with SUPER privilege to write to the database.  With super_read_only, those users cannot write anymore.  But this feature comes with a surprise.

TL&DR: changing super_read_only to ON also sets read_only to ON and setting

                                   Recently, One of our client reached our Remote DBA team with a requirement to reduce the size of the table as it is having many text columns with huge number of records. At preliminary check , I have validated the table size and its row format, as it was  in compressed  format already. 

Later I checked on other possibilities to compress the text columns further, At that time, then I came across per-column compression feature in Percona MySQL server (From 5.7.17-11) which features individual column compression and we were using …

This week is almost over, and it pass after two nice event that I had attended.

PerconaLive 2019 in Amsterdam Schiphol and ProxySQL Technology Day in Ghent.

What are my takeaways on both events?

Well, let us start with PerconaLive first. Venue

The venue was nice, the hotel comfortable and rooms were nice as well, clean and quiet. Allow to have good rest and same time decent space to work if you have to. The conference was just there so I was able to attend, work and rest without any effort, A+.

The hotel was far away from the city and the Amsterdam’s distractions, which it may be a negative thing for many, but honestly IF I spend money, and time of my life to attend a conference, I want to take the most out of it. Have the chance to stay focus on it and to talk with all attendees, customer and experts is a plus. If you want to go around and be a tourist, take a day more after or before the conference …

Starting with the experimental release of Percona XtraDB Cluster 8.0, we have made changes to the SST process to make the process more robust and easier to use.

• mysqldump and rsync are no longer supported SST methods.

  Support for mysqldump was deprecated starting with PXC 5.7 and has now been completely removed.

  MySQL 8.0 introduced a new Redo Log format that limited the use of rsync while upgrading from PXC 5.7 to 8.0. In addition, the new Galera-4 also introduced changes that further limits the use of rsync.

  The only supported SST method is xtrabackup-v2.

• A separate Percona XtraBackup installation is no longer required.

  The required …

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.
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