[Java] How to implement cross database queries similar to presto

### Describe the usage question you have. Please include as many useful details as possible.

The document explanation is not very clear. If I want to cross database query and join two datasets through Arrow, how to do it, how to implement the language layer, Arrow memory format data, how to obtain other services, and through a web server?

### Component(s)

Java

Start by reviewing the existing Arrow Java documentation and its guidance on cross-database queries. Clarify whether the requested work is documentation or an implementation proposal; completion would require a specific scope for the language layer, Arrow memory handling, service access, and web-server integration.

Written by the indexing model from the issue text.