CKB indexer using SQL as the storage backend.
While the SQL based indexer provides the same interface as the basic RocksDB based indexer, using a SQL backend means the developers are free to express more possible queries than the ones enabled in the CellCollector interface.
Note: this is a highly experimental package for now. We are still experimenting and evaluating the proper way to support CKB indexing into SQL database. We might rewrite this package completely at a later time.