On Nov 13, 2008, at 10:39 AM, Damien Katz wrote:
My answer is "Don't do that". Values in documents shouldn't depend
on values in other documents, that's a better fit for a relational
or OO DB. In your example though, CouchDB's views could be used to
compute the sums.
i don't think that's realistic. consider something like the following:
let's say we write a publishing system, users can create documents
with content and tags. at the end of the month the editor is going to
write a summary of the content from that month, obviously this summary
should be tagged with the union of the tags from all summarized
content - for later searching. regardless of whether we store the
tags inside the document or outside of it we have quite a task - we
need to get a consistent read of all content for the month, with all
it's tags, in order to properly construct the summary document with
it's aggregate tags. this isn't strict dependence - it's merely a
read/write consistency issue which nearly any application is going to
face. we can argue that it's not important that the summary of tags
exactly mirrors the tags of it's constituent parts, but that kind of
thinking results not in an information store, but a collection of
valueless data.
anyhow, i think it's important to be able to agree upon best practices
for this kind of operation. saying that values shouldn't depend on
values in other documents is quite a statement - it means couch should
no be used for any information store where the information value needs
to grow recursively. in my case we're modeling financial information
which gets processed in increasingly sophisticated ways - where
documents are inputs to processes which produce other documents. i
can't think of an application that does not do the same thing: a blog
comment depends on the blog post, a 'friends list' depends on the
users, etc.
are you referring to 'values' as different from 'ids' ?
kind regards.
a @ http://codeforpeople.com/
--
we can deny everything, except that we have the possibility of being
better. simply reflect on that.
h.h. the 14th dalai lama
