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Subject: Re: multiview on github
From: J Chris Anderson <jchris@apache.org>
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Date: Thu, 5 Aug 2010 17:26:03 -0700
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On Aug 5, 2010, at 4:32 PM, Jan Lehnardt wrote:

> Hi Norman,
>=20
> I still plan to look at your code, I know the others here
> are fairly busy too, sorry for the review delay :)
>=20

The code looks clean (but could use better comments about where in the =
flow each module comes into play). I don't think we can guess about =
performance, instead we should benchmark to make sure the ring approach =
is right.

In CouchDB currently, it is possible to isolate requests against a =
single db. So you use the security settings to prevent access to =
databases, etc. For this, using the userCtx and switching away from =
couch_db:open_int() would make a big difference.

This way people can query across dbs if they have read access to all of =
them.

I think if you package this as a CouchDB fork on Github and add a few =
JavaScript tests, it will be really useful for some folks. I like that =
it has geo support. Maybe we can target it for inclusion in trunk just =
after GeoCouch goes in trunk (if Volker wants to put it in.)

Also, for realtime hacking on this, you might find that the #couchdb IRC =
channel on Freenode is a good place to solicit feedback. There are a lot =
of people on there doing Geo things that would benefit from this. (They =
really wanna be able to intersect a Geo query with a Map Reduce query, =
etc.)

Chris

> Cheers
> Jan
> --=20
>=20
>=20
> On 5 Aug 2010, at 18:12, Norman Barker wrote:
>=20
>> Hi,
>>=20
>> is there any interest in the multiview, I have fixed (3) below, but =
am
>> still interested in approaches for (1) and (2).
>>=20
>> thanks,
>>=20
>> Norman
>>=20
>> On Fri, Jul 30, 2010 at 3:39 PM, Norman Barker =
<norman.barker@gmail.com> wrote:
>>> Hi,
>>>=20
>>> a very initial version of the multiview is at
>>> http://github.com/normanb/couchdb-multiview for discussion.
>>>=20
>>> The views are intersected by using a ring of processes where each =
node
>>> in the ring represents a view as follows;
>>>=20
>>> % send an id from the start list to the next node in the ring, if =
the
>>> id is in adjacent node then this node sends to the next ring node =
....
>>> % if the id gets all round the ring and back to the start node then =
it
>>> has intersected all queries and should be included. The nodes in the
>>> ring
>>> % should be sorted in size from small to large for this to be =
effective
>>> %
>>> % In addition send the initial id list round in parallel
>>>=20
>>> this is implemented in the couch_query_ring module.
>>>=20
>>> I have a couple of questions
>>>=20
>>> 1) in the module multiview, is there a quicker way to find the =
counts
>>> from startkey to endkey rather than iterating?
>>> 2) In the module couch_query_ring is there a quicker way to test for
>>> inclusion rather than iterating?
>>> 3) Finally, if I hit this concurrently I get an exception,
>>>=20
>>> [error] [<0.201.0>] Uncaught error in HTTP request: {exit,
>>>                                {noproc,
>>>                                 {gen_server,call,
>>>=20
>>> (so ignore my previous email, I am able to trap the msg)
>>>=20
>>> I am going to look into (3) but if you have seen this before.
>>>=20
>>> I am developing on windows, but also test on linux I will work on
>>> getting a linux makefile, but the Makefile.win should be a start.
>>>=20
>>> Any help and comments appreciated.
>>>=20
>>> Norman
>>>=20
>=20