Function parse_catalog_and_schema_from_db_string 

pub fn parse_catalog_and_schema_from_db_string(db: &str) -> (String, String)

Attempt to parse catalog and schema from given database name

The database name may come from different sources:

• MySQL schema name in MySQL protocol login request: it’s optional and user and switch database using USE command
• Postgres database parameter in Postgres wire protocol, required
• HTTP RESTful API: the database parameter, optional
• gRPC: the dbname field in header, optional but has a higher priority than original catalog/schema

When database name is provided, we attempt to parse catalog and schema from it. We assume the format [<catalog>-]<schema>:

• If [<catalog>-] part is not provided, we use whole database name as schema name
• if [<catalog>-] is provided, we split database name with - and use <catalog> and <schema>.