On Jul 13, 2008, at 20:25, Peter Eddy wrote:
On Sun, Jul 13, 2008 at 12:46 PM, Jan Lehnardt <[EMAIL PROTECTED]> wrote:
To get on write view update semantics, you can write a little daemon
script that runs alongside CouchDB and is specified in couch.ini
as DbUpdateNotificationProcesses. This deamon gets sent a
notification each time the database is changed and could in turn
trigger a view update every N document inserts or every Y seconds,
whichever occurs first. The reason not to integrate each doc as
it comes in is that it is horribly inefficient and CouchDB is
designed
to do view index updates very fast, so batching is a good idea.
Thanks for this information, Jan. I think this solution is a lot
better than trying to figure out when it's necessary to update views
in application code. However I'd still argue that people will want
this as their default behavior most of the time, and I wonder if it
wouldn't be more efficient to just build the daemon functionality into
the server, maybe with tunable N and Y values.
I have no number to back it up, but in a usual web-app reads
outnumber writes by far and the incremental index update will
be fast enough. Yes you can always contrive counter examples,
but they can use the proposed solution.
I don't think that an erlang module to handle this would be that
much more efficient than an external daemon. After all, it
is only a few bytes exchanged. But as outlined in my last
paragraph, it makes sense to bundle such a system with
CouchDB but we haven't gotten to it yet. (This is your cue
to jump in *hint* :)
Cheers
Jan
--
- Peter
To get a list of all views in a database, you can do a
GET /db/_all_docs?startkey=_design/&endkey=_design/ZZZZ
(we will have a /db/_all_design_docs view to make the ZZZZ-hack
go away).
That should solve your problem.
Yes, such a daemon should be shipped with CouchDB, but we
haven't got around to work on the deployment infrastructure yet.
Any contributions to this are very welcome. I think the developer's
choice of language for helper scripts is Python, but any will do,
whatever suits you best.
Cheers
Jan
--
The FaQ entry is at the bottom of this page.
http://wiki.apache.org/couchdb/FrequentlyAskedQuestions
BTW: Is there a FaQ module or whatever for MoinMoin? it
would be nice to get a MediaWiki-like table of contents at
the top. Noah?
