On 08/01/2009, at 1:24 PM, Paul Davis wrote:
[..]
function(doc)
{
for(var field in doc)
{
emit([field, doc._id], doc[field]);
}
}
I call that an "exploded index" and worry somewhat about its storage
usage.
Two concerns:
- you'd be needlessly re-storing the large data that the OP wanted to
avoid transferring. Presumably it's big. You might be able to manually
exclude it if it always has the same name, of course
- if there's a lot of records with a lot of small fields, index
overhead might double or even triple the database size
An alternative might be to take the reverse to that approach, and
write a view which returned all the field except the large entry (if
known) you're trying to avoid transferring. That way, you'd avoid
having to re-store those large fields in the index as well.
Storage is cheap*, but obviously it would be bad practise to
needlessly double (or worse) the database size.
I have often wondered the exact overhead of a row in a view index.
Obviously, if it's more than a few bytes, it's going to be a factor to
consider when contemplating view index strategies which generate an
awful lot of index rows. If there are a large number of fields with a
small amount of data in each, and a large number of documents, it is
quite plausible the "exploded index" could be several times the
original size of the data.
Anyone with inside knowledge want to chip in on that? What would be
the approximate overhead, per-entry, of an exploded view index as
described by Paul? Or maybe I should just test it, since I've been
wondering about that for a while ...
Sho
* good storage is not actually cheap
Then to access a specific property:
http://127.0.0.1:5984/db_name/_view/view_name/by_property?
key=["foo", "docid1"]
HTH,
Paul Davis
On Wed, Jan 7, 2009 at 4:18 PM, Robert Koberg <[email protected]> wrote:
Hi,
first, couchdb is just beautiful! :) (using 0.8.1-incubating from
MacPorts)
I am very new, and have read the available docs and several blog
posts.
Can you drill into a doc with a simple GET?
Say I have a doc like:
{"_id": "a", "_rev": "123", "foo":{"bar": 1}, "big-ass-prop": "huge
amount
of stuff"}
Ideally I would like to be able to call something like:
http://127.0.0.1:5984/mydb/a/foo
to return {"bar":1} and avoid downloading "big-ass-prop"
Is this or something like it possible?
(I realize "foo" is a 'sibling' of the _id in the document, but it is
probably treated more like a parent in the DB?)
If not possible, is it possible to create some kind of default
action/filter/? that does something like the above? That is, reads
the
request uri, recognizes it is a document and that there is extra
path info
which should be used to resolve a property.
thanks,
-Rob
