Subpath for EXTERNAL dataset queries

There is a functionality that we added for Analytics external collections some time ago, but i don’t believe there was documentation for it.

It’s here in this patch: https://asterix-gerrit.ics.uci.edu/c/asterixdb/+/17395

The functionality is to allow you to specify kind of a “path” when running a query (under the bucket/definition) from which to read the documents. it adds another layer to the bucket and definition.

The functionality is exposed through a hint called subpath that is provided after the FROM clause and before the name of of the collection. Here is an example.

CREATE ANALYTICS COLLECTION my2019Collection 

ON myReviewsDataContainer 

AT myLink 

USING "reviews/2019" 

WITH {"format": "json"};

SELECT *

FROM /*+ subpath /multi-lines-with-arrays/json */ my2019Collection;

if we haven’t documented, then we should add documentation for it.

I’m referencing some blogs for context.

• https://www.couchbase.com/blog/optimize-performance-of-external-analytics-collections-in-couchbase/
• https://www.couchbase.com/blog/external-datasets-extend-your-reach-with-couchbase-analytics/