Recently I had a customer where every single query was running in a transaction, as well as even the simplest selects. Unfortunately, this is not unique and many connectors like Java love to do that.

In their case, the Java connector changed autocommit=off for the connection itself at the beginning, and as these were permanent connections they never or almost never reconnected.

In the slow query log we could see after every select there was a commit. So why is this a problem?

Test Case

Like always, the best way to deal with a problem to test it. I have created two EC2 instances t3.xlarge with Ubuntu, one for application and one for the databases.  I have used sysbench to run my tests.

I have created a table with 1 million records and was running simple primary key point selects against the database. I was using …

In one of my latest database restore jobs, I was helping a MySQL client with issues related to mysqlbinlog and I wanted to share it here. In case you didn’t know, MySQL is a simple SQL shell with input line editing capabilities, while mysqlbinlog is a utility for processing binary logs a MySQL server. In this case, the server was MariaDB, but the utilities are the same. The database version was 10.1.38-MariaDB.

So, why use mysqlbinlog?

There are many reasons for using mysqlbinlog to process binary log files, but in this case, it was used for point-in-time recovery.

Let’s say you have an erroneous transaction that you run at 3:05 p.m. and your last full backup was run at 12 p.m. To be able to restore your database up to 3:05 p.m., you will need to restore the full backup that you took at 12 p.m. and then apply the events from your binary logs up to the time before you ran the erroneous transaction. This procedure is …

SQL Views Example | Views In SQL Tutorial is today’s topic. SQL views is a kind of virtual tables which have rows and columns as they are in a real database. A view can be accompanied with all the rows of a particular table or selected rows based on a certain condition. In Structured Query Language, a view is a virtual table based on the result-set of an SQL statement.

SQL VIEWS

SQL view contains rows and columns, just like the real table. The fields in the view are fields from one or more real tables in the database. You can add the SQL functions, WHERE, and JOIN statements …

Author: Robert Agar

An organization’s databases contain information that is essential for its survival. This may encompass sensitive customer data, employee records, online sales catalogs, and intellectual capital to name just a few uses of a database. The responsibility of keeping these vital resources available falls to the enterprise’s team of DBAs. Failure to properly maintain these systems can lead to serious negative consequences that can cripple a company’s ability to do business.

Almost every application of any real utility is backed by a database, which in turn is administered through a database management system (DBMS). MySQL is an extremely widely-used DBMS whose popularity is only exceeded by that of Oracle. Countless business-critical applications rely on the availability and performance of MySQL databases. A common …

SLEEP thread causing "Waiting for table metadata lock"
We might have faced some scenarios once our db connection threads are getting locked and we try to find the culprit thread id which is locking the thread, to kill and release the connections. 
Here I am going to focus on one of the scenarios when db connection threads are locked at state "waiting for table metadata lock" and when we see the processlist, we can't find any thread which is running and using the same table, i.e., all threads are in SLEEP state except the locked threads.

Such as : 
mysql [localhost:5726] {msandbox} (world) > show …

During the last conferences, I had the chance to discuss a lot with many colleagues. Some of them, like me, feel we have lost ourselves, not totally but a bit. 

I had start to think why, and this is my reasoning, not saying is right, but I think is not far from the truth.

Let us start just mentioning few events in the 2019 schedule, February Fosdem, end of May Percona live US, mid-June DataOps Barcelona, September Oracle open World, end of September-October Percona Live Europe, plus an undefined number of secondary events or MariaDB roadshows.

Where is the MySQL (and related) conference?

Do not get me wrong, we talk about MySQL a lot during each one of the above (or MariaDB, tometo/tomato). But it seems to me, that in a subtle way, the community had lost his conference.

There is nothing wrong if each company is trying to get the most out of their investment, so implicitly driving the show to get …

Two important MySQL 8.0 Shell Utilities we use regularly are the upgrade checker utility and  JSON import utility . The upgrade checker utility simplifies the pre-upgrade compatibility audit (whether MySQL server instances are ready for upgrade), We have blogged about MySQL upgrade checker utility here . The upgrade checker utility does not support checking MySQL Server instances at a version earlier than MySQL 5.7. From MySQL Shell 8.0.16, the upgrade checker utility can check the configuration file (my.cnf or my.ini) for the server instance. The utility checks for any system variables that are defined in the configuration file but have been removed in the target MySQL Server release, and also for any system variables that are …

(Image credit: Pixabay).

In my earlier post, I showed how MySQL, since version 8.0.14, has support for LATERAL derived tables. With LATERAL, a JOIN can have a second table – a subquery-based derived table – be defined based on values from columns of the first table, and thus be re-calculated for each row of the first table.…

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What is new with MySQL 8.0 Delayed Replication ?

Delayed Replication – You can deliberately execute transactions later than the master by a specific duration of time , Why you do that and for what ? Consider this, Accidentally someone did a wrong UPDATE / DELETE in the master and the transaction is committed, Now how can DBA rollback the database system to the last known good condition ? This is when we benefit from MySQL delayed slave replication investment. The default replication delay in MySQL is “0” seconds, To delay the slave by N seconds use the CHANGE MASTER TO MASTER_DELAY = N, The transactions received from the master is not executed until N seconds later than it’s commit on the immediate master. We have blogged here how to setup …

MySQL Roles are becoming more and more popular. Therefor, we receive more and more questions related to them.

First I encourage you to read this previous 2 posts:

• MySQL 8.0 Roles and GraphML
• MySQL 8.0: Listing Roles

In this post, I will share you some queries I find useful when using MySQL Roles.

Listing the Roles

The first query allows you to list the Roles created on your MySQL Server and if they are assigned to users, and how many:

SELECT any_value(User) 'Role Name', 
       IF(any_value(from_user) is NULL,'No', 'Yes') Active,
       count(to_user) 'Assigned  …