'startkey_docid' should function like 'startkey'
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Key: COUCHDB-485
URL: https://issues.apache.org/jira/browse/COUCHDB-485
Project: CouchDB
Issue Type: Improvement
Components: HTTP Interface
Affects Versions: 0.10
Environment: N/A
Reporter: Christopher Groskopf
Priority: Minor
The 'startkey_docid' and 'endkey_docid' parameters provide a way of
sub-selecting rows for pagination when a view emits many rows with identical
key values. However, it seems both confusing and unintentionally limiting that
'startkey_docid' does not function the same as 'startkey' with regard to how
included documents are identified.
By this I mean, that if a a group of data is emitted with ISO 8601 timestamps
as keys (e.g. "2009-08-25T12:00:00Z") then its possible to specify
'startkey="2009-08"' and include that example data, because it is collated
after 'startkey'. However, it those timestamps were emitted as doc ids instead
of keys, 'startkey_docid' will only act to filter the data if it _exactly_
matches a doc id. Specifying 'startkey_docid="2009-08"' would not filter the
data at all, even if every selected row has the same key.
The benefit of implementing this change is that views which emit many identical
keys could be sub-filtered based on document id. In the case of my
application, the first portion of a document's id is a timestamp, so I would be
able to select a chronological subset of rows after they had been filtered by
key. Another possible use case is where doc ids are slugs--this would make it
possible to select an alphabetical range after specifying a category as a key
parameter.
I haven't looked under the hood and I have never written Erlang, so I have no
way of accurately estimating how significant this change would be. Unless I'm
misunderstanding something, this change should not break existing code.
Looking forward to reading any feedback/comments/alternatives.
Thanks,
Chris
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