During my development I often encounter some issues with database connection when using MuleSoft's Database connector, especially when connecting to an Oracle Database. I researched and found that sometimes but not very often, Oracle in particular have some issue with managing connection pool.
This is just a conjecture from my side, since I can only say that this is from my experience only. So the issue I encountered was, I wasn't able to fetch data from database if I inserted them from Mule Application. i.e. if I inserted some data into Oracle table via SQL Developer, I wasn't able to retrieve from MuleSoft If I use the included Out of the Box connection configuration. I had to configure data source using third party libraries such as DBCP2 or C3PO.
All I did was to configure a Data Source, connection pooling and voila it was working fine without any issue. This behaviour was observed in Mule 4 only.
I tested this behaviour in Mule 4.1.x. I haven't tested this in Mule 4.2 or later. I will update this post with additional details after I have test results from Mule 4.2 and later.
If you guys like this post, please feel free to comment and we can discuss your experiences. Please do let me know if I've mistaken in any of the above, I really appreciate it.