Query multiple collections Arangodb

Question

FOR col_name IN ['col_1', 'col_2']

FOR d IN FULLTEXT(col_name, 'label', @value)

RETURN d

does not works

but

FOR d IN FULLTEXT('col_1', 'label', @value)

RETURN d

works fine

I am using arango 3.4.2-1

Answer 1

in general you can query two collections like this:

FOR col1doc IN col_1
  FILTER col1doc.foo == 'bar'
    FOR col2doc IN col_2
      FILTER col1doc.joinfield == col2doc.joinfield
RETURN {col1doc: col1doc, col2doc: col2doc} 

as its documented in the AQL manual for joins

Please note that simple string equalities can be done using FILTERs and don't need fulltext indices.

To the old fulltext index for two collections you can use subqueries like this:

let col1Documents = (FULLTEXT(col_1, 'label', @value))
let col2Documents = (FULLTEXT(col_2, 'label', @value))

RETURN CONCAT(col1Documents, col2Documents)

The more modern way to achieve this would be to use ArangoSearch views which can handle numerous collections.