Does Marklogic provides a way to search across multiple databases(These databases are in same Marklogic server).
We could manually search in both and collate result but if Marklogic provides then it will be easier and better solution.
MarkLogic has the ability to create sub-databases as part of the Tiered Storage features.
You may be interested in the specific feature of a Super Database
However.... I suggest you consider when this is the best option vs collections or specific forests (range or query indexes as part of the assignment policy) that can be included or excluded as part of your queries.. There are many considerations when using a super-database. As an example, I seem to remember that the total index size may be larger and the sub and super databases need the same index settings. Different databases is the right choice sometimes. I just urge you to consider strongly when to isolate content in completely separate databases that you then want to query together. At the same time, a single sub-database can belong to multiple super-databases - a powerful feature for some use-cases.