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Displaying posts with tag: Java (reset)
High-Performance Java Persistence Newsletter, Issue 22

Introduction Welcome to a new issue of the High-Performance Java Persistence Newsletter in which we share articles, videos, workshops, and StackOverflow answers that are very relevant to any developer who interacts with a database system using Java. Articles From version 2.12, Percona PMM uses Victoria Metrics instead of Prometheus. Victoria Metrics provides better disk I/0 utilization and less memory usage. For more details about this change and its benefits, check out this article. By default, the MySQL JDBC Driver only emulates prepared statements. If you wonder whether server-side prepared statements perform better... Read More

The post High-Performance Java Persistence Newsletter, Issue 22 appeared first on …

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X DevAPI Traffic Compression With Connector/J

X Protocol traffic compression is available on MySQL Server since version 8.0.19. A connector that also supports compression on its end can leverage this feature and reduce the byte streams that are exchanged with the Server.

By default, connections to a MySQL server are uncompressed, thus permitting exchanging data with a client or connector that doesn’t support compression. However, given a client or connector that also supports compression, it is recommended that client and server negotiate the connection compression by default. If this negotiation concludes successfully, both ends can then compress the data they send.

Compression at this level allows reducing the amount of bytes exchanged over the network, but at the cost of additional CPU resources required to run data inflate and deflate operations. The benefits of compression, therefore, occur primarily on low network bandwidth. One can assess the gain or loss due to the …

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MySQL 8.0.20 JDBC

In April, when I updated from MySQL 8.0.17 to MySQL 8.0.19, I found that my Java connection example failed. That’s because of a change in the JDBC driver, which I blogged about then. Starting yesterday, I began updating a base Fedora 30 configuration again to MySQL 8.0.20. I wrote a testing program for the Java JDBC file last time, and when I ran it this time it told me that I didn’t have the JDBC driver installed, or in the $CLASSPATH. My Java diagnostic script,, returned the following error message:

Error: Could not find or load main class MySQLDriver

The Java JDBC test program code is in the prior post. It simply loads the user, password, database, host, and port statically for my student …

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Use MySQL in Quarkus with Hibernate and Panache

Quarkus is a supersonic Java framework built with a cloud-native first mentality. It’s blazing fast in startup and has a much smaller memory footprint compared to Spring Boot. Quarkus is [...]

The post Use MySQL in Quarkus with Hibernate and Panache appeared first on Geeky Hacker.

Java & MySQL 8.0.19

It’s the in-between term time and we’re all stuck at home. I decided to update the image for my Fedora 30 virtual machine. I had a work around to the update issue that I had encountered last October in Bug #96969 but it was not required with the current version. However, after updating from MySQL 8.0.17 to MySQL 8.0.19, I found that my Java connection example failed.

The $CLASSPATH value was correct:


The first error that I got was the my reference to MySQL JDBC driver was incorrect. The error message is quite clear:

Loading class `com.mysql.jdbc.Driver'. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver'. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.
Cannot connect to database server:
The server time zone …
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Communications link failure MySQL JDBC with TLS

Ran into an interesting situation trying to configure a MySQL JDBC driver to connect over TLS (though the driver may call it SSL, TLS is the name for more recent versions of the protocol).

The error I was getting was pretty generic:

Communications link failure The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.

With the relevant parts of the stacktrace, also being non helpful:

at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(
        at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(
        at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(
        at com.mysql.cj.jdbc.ConnectionImpl.(
        at com.mysql.cj.jdbc.ConnectionImpl.getInstance(
        at …
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SQL Triggers Tutorial With Example | Triggers in SQL

SQL Triggers Tutorial With Example | Triggers in SQL is today’s topic. SQL trigger is invoked by the database automatically when any change in the event occurs. It is known as a particular type of stored procedure because triggers are called directly, which is not done in case of stored procedures. The only difference between SQL triggers and stored procedures is that stored procedure needs to be called explicitly, whereas SQL triggers are called implicitly. SQL triggers are invoked when a row is inserted in a table, or any columns are being updated.

SQL Triggers Tutorial With Example

Triggers are the stored programs, which are automatically fired or executed when some events take place. It is like event-based programming. Triggers are written to be executed in the response to any of the …

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Why is My Java Application Freezing Under Heavy I/O Load?

The Question Recently, a customer asked us:

Why would heavy disk IO cause the Tungsten Manager and not MySQL to be starved of resources?

For example, we saw the following in the Manager log file tmsvc.log:

2019/06/03 00:50:30 | Pinging the JVM took 29 seconds to respond.
2019/06/03 00:50:30 | Pinging the JVM took 25 seconds to respond.
2019/06/03 00:50:30 | Pinging the JVM took 21 seconds to respond.
2019/06/03 00:50:30 | Pinging the JVM took 16 seconds to respond.
2019/06/03 00:50:30 | Pinging the JVM took 12 seconds to respond.
2019/06/03 00:50:30 | Pinging the JVM took 8 seconds to respond.

The Answer Why a Java application might be slow or freezing

The answer is that if a filesystem is busy being written to by another process, the background I/O will cause the Java JVM garbage collection (GC) to pause.

This problem is not specific to Continuent Tungsten …

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MySQL Connector/J 8.0.15 has been released

Dear MySQL users,

MySQL Connector/J Version 8.0.15 is the GA release of the 8.0
branch of MySQL Connector/J. It is suitable for use with MySQL Server
versions 8.0, 5.7, 5.6, and 5.5. It supports the Java Database
Connectivity (JDBC) 4.2 API, and implements the X DevAPI.

This release includes the following new features and changes, also
described in more detail on

As always, we recommend that you check the “CHANGES” file in the
download archive to be aware of changes in behavior that might affect
your application.

To download MySQL Connector/J 8.0.15 GA, see the “Generally Available
(GA) Releases” tab at …

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On Innovation. Interview with Scott McNealy

“We made it a point to hire really smart, visionary people and then let them do their work.
I wanted to delegate and let people be in charge of things. My own decision-making process was to decide who got to decide. To make decisions, you have to first outline the problem, and if you hire really great people, they’re going to know more about the problem they’re dealing with than you ever will.”–Scott McNealy

I have interviewed Scott McNealy. Scott is a Silicon Valley pioneer, most famous for co-founding Sun Microsystems in 1982. We talked about Innovation, AI, Big Data, Redis, Curriki and Wayin.


Q1. You co-Founded Sun Microsystems in 1982, and served as CEO and Chairman of the Board for 22 years. What are the main lessons learned in all these years?

Scott …

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