MySql table listener in Java

Question

Here is my requirement:

My java service is continuous running process. When the java service start, it loads the configuration from one of the table in MySql database.

When there are any changes (can be insert/update/delete, outside the java service also possible), java service should reloaded the configuration immediately.

I saw a post in stackoverflow which is for Oracle database, but I am looking for Mysql database.

I can able to achieve this using separate thread, which polling the database table with some interval. But, polling for change is a not a good way to do. Instead, I am looking for any Watcher/Listener which will notify when there is any change in the MySql table.

Can anybody help me to achieve this?

Note: If this question is already answered somewhere, please post the link in the comment, I will remove this question.

it appears like this might help you. after all, it is an sql statement, that will return a result set: serverfault.com/questions/112468/mysql-database-listener — Instinct
– Instinct, Commented Jul 25, 2018 at 7:22
@instinct, Thanks for the response, but again I have to poll the database with some interval right. I am trying to avoid it. — Amaresh Narayanan
– Amaresh Narayanan, Commented Jul 25, 2018 at 7:28
Have you considered using a configuration file or a properties file (instead of a database table)? One can detect the file change using a java.nio.file.WatchService. — prasad_
– prasad_, Commented Jul 25, 2018 at 7:48
There is nothing that works out of the box, you might be interseted in the answers here: stackoverflow.com/questions/23031723/… — StephaneM
– StephaneM, Commented Jul 25, 2018 at 7:59
@prasad, for some other reason, we have to use mysql as configuration source. I had thought about the file as configuration. Anyway, thanks for the comment. — Amaresh Narayanan
– Amaresh Narayanan, Commented Jul 25, 2018 at 8:20

wargre · Accepted Answer · 2018-07-25 08:13:36Z

1

You want to do a Change Data Capture system. Perhaps you could use one based on Kafka.

You can use kafka-connect with Debezium on it. This connector first snapshot your table, then read the mysql binlog to be able to have a consistent kafka topic with insert/modify/delete on the table.

If you don't want use it, perhaps you can fork the code to use the same thing as they do, just modifying the output to be your application listener.

answered Jul 25, 2018 at 8:13

wargre

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2 Comments

Gunnar Over a year ago

No need really to fork; if needed you also can use Debezium as a library embedded into your Java applications, allowing you to manually handle change messages as needed. (Disclaimer: I'm the Debezium project lead)

wargre Over a year ago

Hey, I didn't know this nice feature to embed debezium. Really nice.

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