[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

首先檢閱現有的 Arrow Java 文件及其關於跨資料庫查詢的指引。釐清所要求的工作是文件撰寫還是實作提案；要完成這項工作，需要為語言層、Arrow 記憶體處理、服務存取和 Web 伺服器整合訂定具體範圍。

由索引模型根據 Issue 內容生成。