Thanks for the encouragement!
-> https://issues.apache.org/jira/browse/COUCHDB-3280
Am 24/01/2017 um 6:52 schrieb Adam Kocoloski:
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
