Using the actual view functions would be awfully convenient. People are
going to want comet feeds of their fancy generated views. Having to
rebuild them on the client would be a let down.
How about a view parameter that adds a seq field to each row and orders
results by seq instead of key (but you still get the key)? Could that
even work for reduced views, where seq would be reduced with max()?
With any comet scheme, wouldn't you want to return seq with all DB reads
so that you can sync up your comet gotten data with non-comet data?
Chris Anderson wrote:
On Thu, Dec 11, 2008 at 12:58 PM, Damien Katz <[email protected]> wrote:
I'm thinking of removing the _all_docs_by_seq HTTP view and replacing it
with something that will allow for more flexibility and also allow for Comet
like events, by providing a filter function that finds documents that meet a
criteria, and to be notified immediately when new documents are saved that
meet that criteria. This is meant to be used by the replicator and external
indexers, but to also try to make it be like a regular view and while
supporting all the other stuff is pointlessly complex.
I think if we support an HTTP resource that provides GET and HEAD
responses, representing a range of documents, in a JSON format like
the one views use now, I'd call it a view.
GET /db/_by_seq?since=200&full=true
could return all changes since seq 200. And if a client makes the
request when the db seq is 150, the response will just hang (like
Comet) until 51 seq #s are incremented. We could optimize with a batch
parameter, so the client could request that CouchDB never send less
than N seqs in a single response. Or there could be an option to keep
the connection open while waiting for new seqs to increment. (I think
I'm describing a system Damien remarked about in IRC.)
I guess I think there's some gain to be had if the replication stream
JSON format is similar to what comes back from a view request. For one
thing, it would make it simpler to implement other non-CouchDB
replication clients, which is a good thing.
