is it possible to query design document views with multiple-indices?

[fangq]

I am struggling in creating a design document key to enable flexible queries (involving multiple conditions in AND or OR) of a complex database stored with CouchDB 3.3.2.

After reading related documentations and previous posts on this topic, I realized that it may not be even possible to query a view using more than one condition.

For example, if I let my design document to emit an array key with multiple fields like below (I am not entirely sure if I have to pad 0 to the numbers so that they can be sorted lexically in the right order)

 emit(
  [
   ('0000' + age).slice(-5),
   ('000' + gender).slice(-4),
   ('000' + sessionlist.length).slice(-4),
   ('000' + modalitylist.length).slice(-4),
   ('000' + tasklist.length).slice(-4),
   ('000' + runlist.length).slice(-4),
   subj.substring(4)
  ]
  , null );

I would get keys like ["08300","000M","0001","0001","0001","0000","045"] with the order matching age*100, gender, and length of certain search fields.

With this index, I can search the range of the first field (age) with startkey=["02000",{}]/endkey=["08000",{}], but I as long as I want to use other fields in AND to further filter the data, I could not - from what I understood, couchdb's index left-side keys takes higher priority than the keys on the right, I can only fully determine the left-sided keys first and only allow only one key to filter the data.

I can also use a different index strategy - by emitting multiple keys

emit([('A000' + age).slice(-5),1]);
emit([('G00' + gender).slice(-4),2]);
emit([('S00' + sessionlist.length).slice(-4),3]);
emit([('M00' + modalitylist.length).slice(-4),4]);
emit([('T00' + tasklist.length).slice(-4),5]);
emit([('R00' + runlist.length).slice(-4),6]);

however, the problem with this is still that I can only use one index (startkey/endkey) to filter the data.

I see a number of posts suggesting to create different design documents one for each search key, but again, when using startkey/endkey to query each design document, it can only handle a single condition, not a joint condition.

is it even possible to use views to filter data with multiple keys in CouchDB? am I doing this incorrectly?

[fangq]

anyone wants to share your experience on setting up couchdb design document indices?

[nickva]

I see a number of posts suggesting to create different design documents one for each search key, but again, when using startkey/endkey to query each design document, it can only handle a single condition, not a joint condition.

You're right. Both the map-reduce views and _find queries operate on one underlying b-tree index at a time. It won't work to do arbitrary AND or OR queries on 2+ indices and combine them automatically.

If you go with having multiple design documents, each with a different view, you might be able to make your index a bit more efficient by putting multiple views in the same design document. That way they'll update together when the index updates (but they'll also invalidate together). But you'd still have to query them separately.