Fyi. This flip using index as child source option prefix because we may use the same connector as hybrid child sources. e.g.
create table hybrid_source( f0 varchar, f1 varchar, f2 bigint ) with( 'connector'='hybrid', 'sources'='filesystem,filesystem', '0.path' = '/tmp/a.csv', '0.format' = 'csv', '1.path' = '/tmp/b.csv', '1.format' = 'csv'" ); In this case, we must distinguish the format and path option belonging to which filesystem connector. But as Timo says, it's not clear. He suggest another way like this: CREATE TABLE hybrid_source WITH ( 'sources'='historical;realtime', -- Config option of type string list 'historical.connector' = 'filesystem', 'historical.path' = '/tmp/a.csv', 'historcal.format' = 'csv', 'realtime.path' = '/tmp/b.csv', 'realtime.format' = 'csv'" ) `sources` option is user-custom name instead of the concrete connector type. And we use this user-custom name as prefix, and using prefix.connector to call concrete connector impl.
