Is it possible to use multiple IN operators in one VQL query?
Using multiple IN operators in one VQL query is not supported.
If more than two IN operators are used as below, an error occurs: unsupported operator: IN.
select id, name__v from documents where id in
(select id from document_product__vr where id in (select id from event__c))
Instead of using one VQL query, the user needs to run multiple queries and do some post-processing.
Also, caching any of the previously extracted data locally may save on the API calls.
Vault Help Documentation: Rest API