Hi,
I made views faster! :)
I wrote a patch* that introduces the concept of a view filter.
A new design doc option acts as a document filter and
prevents a doc from getting serialized and sent to the view
server. This is useful to avoid unnecessary computation
when using views that use the `if(doc.type == "foo") {…`
pattern.
* http://github.com/janl/couchdb/commit/a47a4831db74e3e0400c6faaaa29984e10ac861c
The filter works like this:
{
_id:"_design/test_foo",
language: "javascript",
options: {
filter: [{type: "foo"}, {type: "bar"}] // oh hey, proplists in
JSON! :)
},
views: {
all_docs: { // really, only all foo and bar docs
map: "function(doc) { emit(doc.integer, null); }"
}
}
};
If *any* of the `{field, value}`** objects match a *top level* field and
value in a document, it gets sent to the view server.
** Yeah, `field` is not hardcoded to `type`, so if you use
`class:"foo"`,
this patch works for you.
A few notes:
- It would be nice if we could extend this so…
No — I don't like to add any more bells an whistles to this as
eventually this will lead to pure Erlang views which we want
to get anyway.
- In the light of other view server improvements, this might prove
to gain only marginal speed.
- Can we have a filter per view, not a filter per design doc? — Not
without major reworking of the view server and with losing other
optimisations.
I don't think I should just go and commit this without discussion. In
fact, I'd opt to only include this patch if there's demand. I'm happy
to maintain the patch outside of CouchDB for those who need that
speedup.
Cheers
Jan
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