DbVisualizer is a very popular GUI application to view the data stored on a database. It supports various databases such as Oracle, MySQL etc. It relies on different database drivers to connect to the database server and access the data stored there.
In this post, we will try to solve one problem when accessing the latest MySQL database(8.0+) through DbVisualizer. MySQL database starting from 8.0 has lots of changes which may not be compatible with old version of software or libraries which interact with it. There are also lots of issues reported while accessing the 8.0+ version of MySQL database.
The issue we will try to solve is "Unknown system variable 'query_cache_size'". MySQL 8.0+ has removed this query_cache_size setting and if one uses the old JDBC driver to connect to it, the issue would occur.
If one sees this error, first check the JDBC driver being used to connect to the database server. Go to Tools -> Driver Manager... -> MySQL, the current JDBC driver available will be displayed.
The JDBC driver version is 5.1 here which is not the minimum required to access MySQL 8.0+. So go to download the JDBC driver version 8.0+. Once the driver is downloaded, unzip the compressed file and copy the jar file into a folder on the disk. Thereafter on the MySQL driver setting panel, click the +(Open file) button to add the new driver.
Once the driver is added, move the added driver to the top level.
MySQL JDBC driver 8.0 is available now. Close the Driver Manager window and try to connect to the MySQL database again, the database should be able to be connected now.
Hope this helps those who see this issue while using DbVisualizer.
