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From Robert Newson <rnew...@apache.org>
Subject Re: Question about multiple keys with ranges
Date Tue, 14 Feb 2012 15:30:24 GMT
These results;

{"id":"344e921af796598bcd709ba973003c60","key":["26de9c438e5d1c0f075f2ae6ad0b39b2",null,null,null],"value":"344e921af796598bcd709ba973003c60"},
{"id":"344e921af796598bcd709ba973004cd9","key":["26de9c438e5d1c0f075f2ae6ad0b39b2",null,null,null],"value":"344e921af796598bcd709ba973004cd9"},

are the output of your map function, so you *are* emitting null, null,
null from your map function. This explains why your queries don't work
as you expected.

B.

On 14 February 2012 15:21, Mathieu Castonguay <mcastonguay@justlexit.com> wrote:
> I tried lowercase "startkey" it made no difference.
>
> As for the doc.timeScheduled, it's normally formatted timestamps and none
> are null, ie
>
> "2012-02-13T16:18:19.565+0000"
>
>
> On Tue, Feb 14, 2012 at 4:38 AM, Simon Metson <simonmetson@googlemail.com>wrote:
>
>> Hi,
>> Looks like the Date.parse is failing, try emitting the doc.timeScheduled
>> as the value instead of the _id (aside: it's probably not worth emitting
>> the _id as a value since it's in the view result anyway...) and then
>> checking on the command line that what's returned is parseable.
>> Cheers
>> Simon
>>
>>
>> On Tuesday, 14 February 2012 at 01:54, Mathieu Castonguay wrote:
>>
>> > Actually disregard that, it's still not working... :(
>> >
>> > The view:
>> >
>> > function(doc) { if(doc.userId && doc.timeScheduled) {var d = new
>> > Date(Date.parse(doc.timeScheduled)); emit([doc.userId,
>> > d.getFullYear(), d.getMonth(), d.getDate()], doc._id)} }
>> >
>> >
>> >
>> > When I do ?startKey=["226de9c438e5d1c0f075f2ae6ad0bcc82",2012,1,11]
>> >
>> > I get these results, which seems to get null for those values.
>> >
>> >
>> {"id":"344e921af796598bcd709ba973003c60","key":["26de9c438e5d1c0f075f2ae6ad0b39b2",null,null,null],"value":"344e921af796598bcd709ba973003c60"},
>> >
>> {"id":"344e921af796598bcd709ba973004cd9","key":["26de9c438e5d1c0f075f2ae6ad0b39b2",null,null,null],"value":"344e921af796598bcd709ba973004cd9"},
>> >
>> {"id":"344e921af796598bcd709ba973001d3f","key":["26de9c438e5d1c0f075f2ae6ad0bcc82",null,null,null],"value":"344e921af796598bcd709ba973001d3f"},
>> >
>> {"id":"344e921af796598bcd709ba973002c01","key":["26de9c438e5d1c0f075f2ae6ad0bcc82",null,null,null],"value":"344e921af796598bcd709ba973002c01"}
>> >
>> > If I do the full thing with the end key:
>> >
>> ?startKey=["226de9c438e5d1c0f075f2ae6ad0bcc82",2012,1,11]&endkey=["226de9c438e5d1c0f075f2ae6ad0bcc82",2012,3,25]
>> >
>> > I get no results:
>> >
>> > {"total_rows":4,"offset":0,"rows":[]}
>> >
>> >
>> > On Mon, Feb 13, 2012 at 8:18 PM, Mathieu Castonguay <
>> > mcastonguay@justlexit.com (mailto:mcastonguay@justlexit.com)> wrote:
>> >
>> > > Yes, it was me that misunderstood your example, I've been trying a few
>> > > things now and it's working great, thank you for your help.
>> > >
>> > >
>> > > On Mon, Feb 13, 2012 at 7:46 PM, Michael Miller <mike@cloudant.com(mailto:
>> mike@cloudant.com)> wrote:
>> > >
>> > > > Thanks Simon,
>> > > >
>> > > > Mathieu I'm afraid that I may have misunderstood what you're trying
>> to
>> > > > do. I assumed the timestamp was a static property of the document.
>> The
>> > > > role of the map function is to render those static properties into
a
>> static
>> > > > index, and then to use dynamic start/stop keys at query time to to
>> range
>> > > > queries. It's a common misperception to thing that you are
>> interacting
>> > > > with the map function at query time, but you aren't. You can only
>> interact
>> > > > with the output of the map function, so you want to put the logic
>> into the
>> > > > startkey/endky to slice into the index appropriately. Are we on the
>> right
>> > > > track?
>> > > >
>> > > > -M
>> > > >
>> > > > On Feb 13, 2012, at 4:33 PM, Simon Metson wrote:
>> > > >
>> > > > > Hi,
>> > > > > Do you mean how do you query the view for a given date? Once
the
>> > > > >
>> > > >
>> > > > document is written I'd assume it has a fixed date, e.g. you'd do
>> something
>> > > > like:
>> > > > > > var d = new Date(Date.parse(doc.date));
>> > > > >
>> > > > >
>> > > > >
>> > > > > You don't want to dynamically generate the date in the view,
as
>> this
>> > > > will be the date the view was created, not the date of the query or
>> the
>> > > > date associated to the data.
>> > > > > Cheers
>> > > > > Simon
>> > > > >
>> > > > >
>> > > > > On Monday, 13 February 2012 at 21:27, Mathieu Castonguay wrote:
>> > > > >
>> > > > > > Thanks for the explanation Michael. This works great if
you
>> already
>> > > > know
>> > > > > > the value of the date, but if it's dynamic, how can I replace
>> this line
>> > > > > >
>> > > > > > var d = new Date(Date.parse("2012-02-11T22:00:00"))
>> > > > > >
>> > > > > > with the date from the key? Can I access key[0] or something
>> along
>> > > > those
>> > > > > > lines from inside my map function?
>> > > > > >
>> > > > > > On Mon, Feb 13, 2012 at 3:46 PM, Michael Miller <
>> mike@cloudant.com (mailto:mike@cloudant.com)(mailto:
>> > > > mike@cloudant.com (mailto:mike@cloudant.com))> wrote:
>> > > > > >
>> > > > > > > Hi Mathieu,
>> > > > > > >
>> > > > > > > Sorry to jump in on this conversation late. This is
a bit
>> verbose, but
>> > > > > > > I've seen this question go by unanswered way too many
times and
>> > > > > > >
>> > > > > >
>> > > > > >
>> > > > >
>> > > >
>> > > > decided to
>> > > > > > > be proactive.
>> > > > > > >
>> > > > > > > *Long story short: CouchDB is ideal for this, even
on big data
>> sets.
>> > > > It
>> > > > > > > will be fast at scale.
>> > > > > > >
>> > > > > > > * Details: When working with dates in couchdb, I almost
always
>> find
>> > > > > > > myself using the following pattern:
>> > > > > > >
>> > > > > > > 1) Store the date-time in either epoch seconds or a
ISO std
>> format,
>> > > > both
>> > > > > > > of which are convenient to work with in javascript
(for
>> server-side
>> > > > > >
>> > > > >
>> > > >
>> > > > views
>> > > > > > > as well as client applications). Your choice of ISO
8601
>> formatted
>> > > > > >
>> > > > >
>> > > >
>> > > > works
>> > > > > > > nicely with the JS Date class:
>> > > > > > >
>> > > > > > > var d = new Date(Date.parse("2012-02-11T22:00:00"))
>> > > > > > >
>> > > > > > > 2) Then, in preparation for future reduces you will
likely end
>> up
>> > > > wanting,
>> > > > > > > I'd use a compound key structured like:
>> > > > > > > [<userId>, year, month, day]
>> > > > > > >
>> > > > > > > So, the map code would be:
>> > > > > > >
>> > > > > > > function(doc){
>> > > > > > > if (doc && doc.userId && doc.timeScheduled
&& doc.dollarValue)
>> {
>> > > > > > > var d = new Date(Date.parse("2012-02-11T22:00:00"));
>> > > > > > > //note, Month runs [0,11]
>> > > > > > > emit( [doc.userId, d.getFullYear(), d.getMonth(), d.getDate()],
>> > > > > > > doc.dollarValue);
>> > > > > > > }
>> > > > > > > }
>> > > > > > >
>> > > > > > > where I've assumed that you may want to aggregate on
some
>> fictitious
>> > > > > > > doc.dollarValue numerical field. For that, you would
add to
>> your
>> > > > > > >
>> > > > > >
>> > > > >
>> > > >
>> > > > design
>> > > > > > > document a builtin reduce function:
>> > > > > > >
>> > > > > > > "reduce": "_stats"
>> > > > > > >
>> > > > > > > to get the count, sum, min value, max value, mean and
std-dev.
>> Let's
>> > > > > > > suppose we call this view "idByTime" and it lives in
the
>> design_doc
>> > > > > > >
>> > > > > >
>> > > > >
>> > > >
>> > > > called
>> > > > > > > "selectors".
>> > > > > > >
>> > > > > > > 3) Now, to query this for the SELECT you want you would
do:
>> > > > > > >
>> > > > > > > curl -X GET '
>> > > >
>> http://demo.cloudant.com/dbname/_design/sectors/_view/idByTime?reduce=false&startkey=\[
>> > > > > > > "bob",2012,0,1\]&endkey=\["bob",2012,0,25\]'
>> > > > > > >
>> > > > > > > to get the list of document ids that fall within Jan
1, 2012
>> and Jan
>> > > > 25,
>> > > > > > > 2012 for user id "bob".
>> > > > > > >
>> > > > > > > Now, if you want to get the full documents, you can
just
>> change that
>> > > > to:
>> > > > > > >
>> > > > > > > curl -X GET '
>> > > >
>> http://demo.cloudant.com/dbname/_design/sectors/_view/idByTime?reduce=false&startkey=\[
>> > > > > > > "bob",2012,0,1\]&endkey=\["bob",2012,0,25\]&include_docs=true'
>> > > > > > >
>> > > > > > > 4) Now, the real fun comes when you can use that same
index to
>> do
>> > > > > > > query-time rollup that's super fast. For this the thing
you
>> want to
>> > > > > > >
>> > > > > >
>> > > > >
>> > > >
>> > > > note
>> > > > > > > is the group_level option at query time. If you have
a key of
>> 'n'
>> > > > > > > dimensions (n=4 in our case), then you can roll it
up from
>> > > > > > >
>> > > > > >
>> > > > >
>> > > >
>> > > > dimensionality
>> > > > > > > n=0 through n=4. So, at full dimensionality:
>> > > > > > >
>> > > > > > > curl -X GET '
>> > > >
>> http://demo.cloudant.com/dbname/_design/sectors/_view/idByTime?group_level=4
>> > > > > > > '
>> > > > > > >
>> > > > > > > will give you the values for all users aggregated by
day. You
>> can add
>> > > > > > > startkey and endky just as before to slice into the
range.
>> > > > > > >
>> > > > > > > Now if you want to roll it up by user/year/month:
>> > > > > > >
>> > > > > > > curl -X GET '
>> > > >
>> http://demo.cloudant.com/dbname/_design/sectors/_view/idByTime?group_level=3
>> > > > > > > '
>> > > > > > >
>> > > > > > > by user/year:
>> > > > > > >
>> > > > > > > curl -X GET '
>> > > >
>> http://demo.cloudant.com/dbname/_design/sectors/_view/idByTime?group_level=2
>> > > > > > > '
>> > > > > > >
>> > > > > > > by user:
>> > > > > > >
>> > > > > > > curl -X GET '
>> > > >
>> http://demo.cloudant.com/dbname/_design/sectors/_view/idByTime?group_level=1
>> > > > > > > '
>> > > > > > >
>> > > > > > > and ultimately roll up over all users:
>> > > > > > >
>> > > > > > > curl -X GET '
>> > > >
>> http://demo.cloudant.com/dbname/_design/sectors/_view/idByTime?group_level=0
>> > > > > > > '
>> > > > > > >
>> > > > > > > Note that group_level=0 => "group=false", and group_level
= n
>> =>
>> > > > > > > "group=true" in the view query options at:
>> > > > > > >
>> > > > > > > http://wiki.apache.org/couchdb/HTTP_view_API#Querying_Options.
>> > > > > > >
>> > > > > > > I prefer to just be explicit with the group_level and
forget
>> that
>> > > > > > > group=true/false exists.
>> > > > > > >
>> > > > > > > Thanks, Mike
>> > > > > > >
>> > > > > > > p.s., apologies for any typos, I was cribbing this
from some
>> cloudant
>> > > > > > > blog-posts in the making.
>> > > > > > >
>> > > > > > >
>> > > > > > >
>> > > > > > > On Feb 13, 2012, at 11:11 AM, Mathieu Castonguay wrote:
>> > > > > > >
>> > > > > > > > I tried that exact example with
>> > > >
>> ?startKey=["26de9c438e5d1c0f075f2ae6ad0bcc82","2012-02-11T22:00:00"]&endkey=["26de9c438e5d1c0f075f2ae6ad0bcc82",{}]
>> > > > > > > > and I still get records in the past:
>> > > > > > > >
>> > > > > > > > {"total_rows":3,"offset":0,"rows":[
>> > > >
>> {"id":"344e921af796598bcd709ba973003c60","key":["26de9c438e5d1c0f075f2ae6ad0b39b2","2012-02-13T16:18:19.565+0000"],"value":"344e921af796598bcd709ba973003c60"},
>> > > > > > > >
>> > > > > > >
>> > > > > >
>> > > > >
>> > > >
>> > > >
>> {"id":"344e921af796598bcd709ba973001d3f","key":["26de9c438e5d1c0f075f2ae6ad0bcc82","2012-02-10T21:44:14.920+0000"],"value":"344e921af796598bcd709ba973001d3f"},
>> > > > > > > >
>> > > > > > >
>> > > > > >
>> > > > >
>> > > >
>> > > >
>> {"id":"344e921af796598bcd709ba973002c01","key":["26de9c438e5d1c0f075f2ae6ad0bcc82","2012-02-10T22:05:48.218+0000"],"value":"344e921af796598bcd709ba973002c01"}
>> > > > > > > > ]}
>> > > > > > > >
>> > > > > > > >
>> > > > > > > > The view's map function is:
>> > > > > > > >
>> > > > > > > > function(doc) { if(doc.userId && doc.timeScheduled)
>> > > > > > > > {emit([doc.userId,doc.timeScheduled], doc._id)}
}
>> > > > > > > >
>> > > > > > > >
>> > > > > > > >
>> > > > > > > >
>> > > > > > > > On Mon, Feb 13, 2012 at 1:55 PM, James Klo <jim.klo@sri.com(mailto:
>> jim.klo@sri.com) (mailto:
>> > > > jim.klo@sri.com (mailto:jim.klo@sri.com))> wrote:
>> > > > > > > >
>> > > > > > > > > Not sure how you are querying, but are you
doing the
>> equivalent to
>> > > > this?
>> > > > > > > > > startkey and endkey should be expressed as
JSON
>> > > > > > > > >
>> > > > > > > > > curl -g '
>> > > >
>> http://localhost:5984/orders/_design/Order/_view/by_users_after_time?startkey=[
>> > > > > > > > >
>> > > > > > > >
>> > > > > > >
>> > > > > >
>> > > > >
>> > > >
>> > > >
>> "f98ba9a518650a6c15c566fc6f00c157","2012-01-01T11:40:52.280Z"]&endkey=["userid",{}]'
>> > > > > > > > >
>> > > > > > > > >
>> > > > > > > > > *
>> > > > > > > > > Jim Klo
>> > > > > > > > > Senior Software Engineer
>> > > > > > > > > Center for Software Engineering
>> > > > > > > > > SRI International
>> > > > > > > > > e. jim.klo@sri.com (mailto:jim.klo@sri.com)
>> > > > > > > > > p. 805.542.9330 x121
>> > > > > > > > > m. 805.286.1350
>> > > > > > > > > f. 805.546.2444
>> > > > > > > > > *
>> > > > > > > > >
>> > > > > > > > > On Feb 13, 2012, at 10:27 AM, Mathieu Castonguay
wrote:
>> > > > > > > > >
>> > > > > > > > > I tried reversing the keys with no luck.
I still get
>> timestamps that
>> > > > > > > are in
>> > > > > > > > > the past (before the startKey).
>> > > > > > > > >
>> > > > > > > > > On Sat, Feb 11, 2012 at 6:37 PM, James Klo
<
>> jim.klo@sri.com (mailto:jim.klo@sri.com)(mailto:
>> > > > jim.klo@sri.com (mailto:jim.klo@sri.com))> wrote:
>> > > > > > > > >
>> > > > > > > > > Reverse the key. [userid, time]
>> > > > > > > > >
>> > > > > > > > >
>> > > > > > > > > CouchDB is all about understanding collation.
Basically
>> views are
>> > > > > > > > >
>> > > > > > > > > sorted/grouped from left to right alphanumeric.
See
>> > > > > > > > >
>> > > > > > > > > http://wiki.apache.org/couchdb/View_collation
for the
>> finer
>> > > > details as
>> > > > > > > > >
>> > > > > > > > > there are more rules than the basics I mention.
>> > > > > > > > >
>> > > > > > > > >
>> > > > > > > > > so the reversal sorts the view by userid
first, then date
>> as string.
>> > > > > > > > >
>> > > > > > > > > Instead of sorting by dates then userids.
>> > > > > > > > >
>> > > > > > > > >
>> > > > > > > > > You do it this way because you know the exact
userid, but
>> not the
>> > > > exact
>> > > > > > > > >
>> > > > > > > > > date. If you knew the exact date, but not
the userid, what
>> you have
>> > > > > > > > >
>> > > > > > > > > currently would be better.
>> > > > > > > > >
>> > > > > > > > >
>> > > > > > > > > - Jim
>> > > > > > > > >
>> > > > > > > > >
>> > > > > > > > >
>> > > > > > > > > Sent from my iPad
>> > > > > > > > >
>> > > > > > > > >
>> > > > > > > > > On Feb 11, 2012, at 1:54 PM, "Mathieu Castonguay"
<
>> > > > > > > > >
>> > > > > > > > > mcastonguay@justlexit.com (mailto:
>> mcastonguay@justlexit.com)>
>> > > > wrote:
>> > > > > > > > >
>> > > > > > > > >
>> > > > > > > > > I have a simple document named Order structure
with the
>> fields id,
>> > > > name,
>> > > > > > > > >
>> > > > > > > > > userId and timeScheduled.
>> > > > > > > > >
>> > > > > > > > >
>> > > > > > > > > What I would like to do is create a view
where I can find
>> the
>> > > > > > > > >
>> > > > > > > > > document.idfor those who's userId is some
value and
>> timeScheduledis
>> > > > > > > > >
>> > > > > > > > > after a given date.
>> > > > > > > > >
>> > > > > > > > >
>> > > > > > > > > My view:
>> > > > > > > > >
>> > > > > > > > >
>> > > > > > > > > "by_users_after_time": {
>> > > > > > > > >
>> > > > > > > > > "map": "function(doc) { if (doc.userId &&
>> doc.timeScheduled) {
>> > > > > > > > >
>> > > > > > > > > emit([doc.timeScheduled, doc.userId], doc._id);
}}"
>> > > > > > > > >
>> > > > > > > > > }
>> > > > > > > > >
>> > > > > > > > >
>> > > > > > > > > If I do
>> > > >
>> localhost:5984/orders/_design/Order/_view/by_users_after_time?startKey="[2012-01-01T11:40:52.280Z,f98ba9a518650a6c15c566fc6f00c157]"
>> > > > > > > > >
>> > > > > > > > > I get every result back. Is there a way to
access key[1]
>> to do an if
>> > > > > > > > >
>> > > > > > > > > doc.userId == key[1] or something along those
lines and
>> simply emit
>> > > > on
>> > > > > > > > >
>> > > > > > > > > the
>> > > > > > > > >
>> > > > > > > > > time?
>> > > > > > > > >
>> > > > > > > > >
>> > > > > > > > > This would be the SQL equivalent of select
id from Order
>> where
>> > > > userId =
>> > > > > > > > >
>> > > > > > > > > "f98ba9a518650a6c15c566fc6f00c157" and timeScheduled
>
>> > > > > > > > >
>> > > > > > > > > 2012-01-01T11:40:52.280Z;
>> > > > > > > > >
>> > > > > > > > >
>> > > > > > > > > I did quite a few Google searches but I can't
seem to find
>> a good
>> > > > > > > > >
>> > > > > > > > > tutorial
>> > > > > > > > >
>> > > > > > > > > on working with multiple keys. It's also
possible that my
>> approach
>> > > > is
>> > > > > > > > >
>> > > > > > > > > entirely flawed so any guidance would be
appreciated.
>> > > > > > > > >
>> > > > > > > > >
>> > > > > > > > > Thank you,
>> > > > > > > > >
>> > > > > > > > >
>> > > > > > > > > Matt
>>
>>

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