Introduction When executing an entity query (e.g. JPQL, HQL or Criteria API), you can use any SQL function without having to register it as long as the function is passed directly to the WHERE clause of the underlying SQL statement. However, if the SQL function is used in the SELECT clause, and Hibernate has not … Continue reading The best way to use SQL functions in JPQL or Criteria API queries with JPA and Hibernate →

The post The best way to use SQL functions in JPQL or Criteria API queries with JPA and Hibernate appeared first on Vlad Mihalcea.

MySQL partitioning makes data distribution of individual tables (typically we recommend partition for large & complex I/O table for performance, scalability and manageability) across multiple files based on partition strategy / rules. In very simple terms, different portions of table are stored as separate tables in different location to distribute I/O optimally. The user defined division of data by some rule is known as partition function, In MySQL we partition data by RANGE of values / LIST of values / internal hashing function / linear hashing function. By restricting the query examination on the selected partitions by matching rows increases the query performance by multiple times compared to the same query on a non partitioned table, This methodology is also called partition pruning (trimming of unwanted partitions), Please find below example of partition pruning:

The common wisdom with database performance management is that a “cold” database server has poor performance. Then, as it “warms up”, performance improves until finally you reach a completely warmed up state with peak database performance. In other words, that to get peak performance from MySQL you need to wait for database warm up.

This thinking comes from the point of view of database cache warmup. Indeed from the cache standpoint, you start with an empty cache and over time the cache is filled with data. Moreover the longer the database runs, the more statistics about data access patterns it has, and the better it can manage database cache contents.

Over recent years with the rise of SSDs, cache warmup has become less of an issue. High Performance NVMe Storage can do more than 1GB/sec read, meaning you can warm up a 100GB database cache in less than 2 minutes. Also, SSD IO latency tends to be quite good so you’re not …

Amazon RDS for MySQL offers the option to automate minor version upgrades using the minor version upgrade policy, a property that lets you decide if Amazon is allowed to perform the upgrades on your behalf. Usually the goal is not to upgrade automatically every RDS instance but to keep up to date automatically non-production deployments. This helps you address engine issues as soon as possible and improve the automation of the deployment process.

If your are using the AWS Command Line Interface (CLI) and you have an instance called test-rds01 it is as simple as changing

[--auto-minor-version-upgrade | --no-auto-minor-version-upgrade]

For example:

aws rds modify-db-instance --db-instance-identifier test-rds01 --apply-immediately …

Announcing the opening of the Percona Live Europe Open Source Database Conference 2018 in Frankfurt, Germany call for papers. It will be open from now until August 10, 2018. The conference takes place November 5–7.

Our theme this year is
Connect. Accelerate. Innovate.

As a speaker at Percona Live Europe, you’ll have the opportunity to CONNECT with your peers—open source database experts and enthusiasts who share your commitment to improving knowledge and exchanging ideas. ACCELERATE your projects and career by presenting at the premier open source database event, a great way to build your personal and company brands. And influence the evolution of the open source software movement by demonstrating how you INNOVATE!

Community initiatives …

In MariaDB 10.2.12, these two don’t yet work together. GTID = Global Transaction ID.  In the master-slave asynchronous replication realm, this means that you can reconnect a slave to another server (change its master) and it’ll happily continue replicating from the correct point.  No more fussing with filenames and offsets (which of course will both differ on different machines).

So in concept the GTIID is “globally” unique – that means it’s consistent across an entire infra: a binlogged write transaction will have the same GTID no matter on which machine you look at it.

• OK: if you are transitioning from async replication to Galera cluster, and have a cluster as slave of the old infra, then GTID will work fine.
• PROBLEM: if you want to run an async slave in a Galera cluster, GTID will currently not work. At least not reliably.

The overview issue is …

There could be from one to over ten ports used within your MySQL ecosystem.  It really depends on what you have enabled, which components you are using, how your applications connect, and other characteristics of your environment.

From a security point, these ports need to be opened just wide enough to allow the various components  that should communicate to talk while blocking out anything else trying to hack its way in – the goal being to enforce the security principle of “least privilege”. …

Since MySQL 5.7 we have a new player in the field, MySQL InnoDB Cluster. This is an Oracle High Availability solution that can be easily installed over MySQL to get High Availability with multi-master capabilities and automatic failover.

This solution consists in 3 components: InnoDB Group Replication, MySQL Router and MySQL Shell, you can see how these components interact in this graphic:

In this three blog post series, we will cover each of this components to get a sense of what this tool provides and how it can help with architecture decisions.

Group Replication

This is …

Scary movies for teenagers and database administration tasks share some common traits. Usually, the movie starts with a group of teens making unwise choices. Maybe you, as a DBA, are no longer a teenager, but you shouldn’t underestimate your ability to do the same.

$ sudo su -
Darrera entrada: ds jun 2 14:43:53 UTC 2018 des de a a pts/0
[root@mysql ~]# cd /var/lib/mysql
[root@mysql mysql]# df -h .
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00 38G 35G 3G 92% /
[root@mysql mysql]#

Back to the movie…today is just another regular day. Checking Jira (or whatever your ticketing system is), answering emails and phone calls. Maybe a couple of meetings. And in the meantime, you will perform some critical tasks on the most important systems for your company. Just the usual stuff!

[root@mysql mysql]# ls -l *.log
ls: cannot access *.log: No such file or directory
[root@mysql mysql]# ls -l *log*
-rw-r-----. 1 …

There was an interesting but hard to read post on StackOverflow about how 'insert select delete' data from a MySQL JSON data type column.  The first line of the writer's problem is a little confusing '
In order to record user mac_address and count mac_address to restrict user login's pc or notebook to control user available max for example (it's work)' but the examples reveled more about what was desired. The idea was to track MAC address used by various users and the author of the question was wondering how to up data a JSON Array of values with JSON_INSERT.  INSERT is for inserting and the better choice would be JSON_ARRAY_APPEND or JSON_ARRAY_INSERT.    But what caught my eye was the second question: Select sql command for json column ? could be …