On Sep 16, 2009, at 11:51 PM, Paul Davis wrote:
I don't think I see how this would affect a partitioning scheme. I
guess it could make people more willing to split documents that might
be better served as a single doc, but that'd be the same regardless
with features like multi-key fetch.
Actually, it is the other way around. The wiki proposal effectively
uses docid as an entity identifier and would provide advantages to
designs where an entity and doc are synonymous. The patch can
accomplish the same end result, but it doesn't add magic to the JSON.
This appears to be better, but it seems to be assigning some magic
behavior
to the second argument so it specifies both the value. Was there
previous
discussion or a bug report filed on this that I missed?
There wasn't a ticket, but the new bit is only a minor tweak to a
lesser know feature. Using the _rev member of an emitted object comes
from the ?include_docs=true feature. When I wrote that I fretted over
the race condition of pulling a doc revision that was different than
the one that emitted the row. The best answer at the time was "allow
people to specify a _rev" which was all and good.
The new bit just extends that slightly.
I'm thinking it would be cleaner to support an optional 3 argument
to emit
with { _id:"", _rev:"" }? The current two argument emit() would be
the
equivalent of emit(key, value, { _id:doc._id, _rev:doc.rev}).
I think this is a pretty good idea. Though unless I'm missing
something the implementation difficulty rises noticeably. The only
initial drawback I see is how we explain the semantics of default
behavior. For ?include_docs=true it was simply "current version or
version specified by _rev". Obviously adding _id makes that weirder,
but I'm don't see a more clear explanation with the third parameter
version.
Paul Davis
In the current code, I don't see how you would emit a string, array or
other value and also affect the included documents. If added as a
third parameter, we could also dispense with using the underscores in
the argument, so it would really be:
emit(key, value, { id:doc._id, rev:doc._rev});
