Support for TSDB

[minorcong]

• Internal: We should find databases to improve the performance of curve queries. Of course, inappropriate ORM should be the first one to be replaced.
• External: CSV is a simple format, but it can't satisfy all scenes. We MAY support a method to add data directly from external database.

[linjinjin123]

You can try Druid, an open-source data store designed for sub-second queries on real-time and historical data.