Hi Norbert, I quite like this proposal. I’d suggested something similar a few years back when we were first designing Mango but we never got around to implementing it. I’d defer to Paul, Tony or anyone else deeply familiar with Mango on the level of effort required to establish this linkage, but it doesn’t seem crazy. If you like, please create an issue in JIRA:
https://issues.apache.org/jira/browse/COUCHDB You’ll need an account first if you don’t already have one: https://issues.apache.org/jira/secure/Signup!default.jspa Cheers, Adam > On Jan 20, 2017, at 1:10 PM, Norbert Nemec <[email protected]> wrote: > > Hi there, > > I am quite new to the world of CouchDB and I know that this is quite a > fundamental proposal, but I very much hope that it will still be received and > discussed openly: > > The Mango Query Server aims at offering a simpler alternative to MapReduce > queries. As it stands now, it is also fundamentally limited in terms of > expressiveness an performance. Indices can be defined only over a plain set > of fields with none of the possibilities that a map function offers. > Selectors allow powerful combinations, but require to perform much of the > computational effort at query time. The $regex operator, for example even > contains a warning about this in the documentation. > > My proposal would be to add an alternative way to define indices by > explicitly providing a design document map function. The 'fields' argument of > such a "computed index" would not have to exist as an actual field in the > database, but would be made available as a "computed field" for regular use > in subsequent find requests. > > Ultimately, this approach would bridge the gap between the simple-but-limited > Mango queries and the powerful-but-unwieldy MapReduce queries. Rather than > having to decide between both approaches, developers could start with the > simple Mango approach and then just learn one more concept if they need the > full power. > > (It is my understanding that the currently recommended approach is to add > computed fields to the documents directly at creation time. Though this is a > workaround for the limitations of selectors, it does not offer any guarantees > for internal consistency of a database and mixes the concerns of content > creation with those of retrieval.) > > Thank you for your careful consideration. I am looking forward to > constructive discussion! > > Greetings, > Norbert Nemec
