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From Benoit Chesneau <>
Subject Re: show/list
Date Thu, 14 Nov 2013 18:24:39 GMT
On Thu, Nov 14, 2013 at 6:58 PM, Filippo Fadda <> wrote:

> Any application that uses CouchDB as a pure database doesn't need show and
> list handlers. They are simply useless, in fact I didn't implement (yet)
> them in ElephantOnCouch library because I don't see any use case for them.
> And I'm not sure if I will never implement them, probably not. If you are
> using Ruby, Python, PHP, you'll never produce HTML directly from CouchDB,
> because there are frameworks in plenty with template engines aimed to do
> the job.
> I don't know the history about show and list, but they remember me Lotus
> Domino. Of course you need them if you are developing a CouchApp.
> -Filippo

On the contrary I think they are very useful for a database. A rather smart
way to  transform and query the data (doc or views).

To do a bit of history the first proposal for them had only one handler
called "form", a way to format the data or send a form.  We settled on a
simpler form distinguishing docs and views and the way to handle them.
Sometime after you had the updates functions. They are not per see related
to the couchapps. You can do couchapps without them.

On the other contrary lists and shows are a way to handle in memory on the
server side the results you fetch and provides new results depending on the
params you pass to the URL. All results can the be streamed to the client.
They can replace in some cases the queries you can do on some dbs like the
relational db or some document databases with more capabilities of query by
default. After all most of a SQL query is handled in memory.

But actually they have their caveats. They can be slow due to the way the
JS engine work. The way we can improve this is known (in fact there aremany
different way: improving the messages between erlang and js, adding a DSL,
using a native language..). The other thing that should be improved is the
way the lists are working. For now we can't access to more than one view
(or secondary index) in a list which means we can't do yet complex queries
based on multiple index(views) like a relational or others databases like
datomic can do. Such change should be easy though.

In short I don;t think we should deprecate such functions. We should on the
contrary improve them. And stop to associate them to "couchapps". They are

- benoit

> On Nov 14, 2013, at 5:49 PM, wrote:
> > Hi all,
> >
> > just watched Joan Touzet presentation
> > (
> >
> > )
> > On slide 27 she says:
> >
> > "... show/list is the last resort ..."
> > "... it is _not_ for rendering images (ok) html (?) ..."
> > "... show/list is ugly ...should probably be deprecated ..."
> >
> > I like the concept of show/list and would like to know
> > what the community thinks.
> >
> >
> > Regards
> > Thomas

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