Lookups / one key -> multiple values

Suppose you use druid to store web tracking data (url).
Suppose also you assign one or more categories to each url in a mysql database.

What would be the best way to query druid on categories? I thought I would create a lookup that would give me a multi value dimension.

However, according to my tests, the lookup is a single value dimension. Am I right ?

note that according to documentation the “tsv lookupParseSpec” has a listDelimiter parameter

It should fail on


in MapPopulator.java because the map is only <String, String> and does not accept <String, List>

The option is there because the parser accepts the option, but it should break things if you try to use it.