I'm not sure if that will give me what I want exactly.
I want to search for these exact numbers only nothing in-between
>> 0123456789
>> 012345678
>> 01234567
>> 0123456
>> 012345
>> 01234
Therefore the most documents it could possibly return is 6 i.e. even though
startKey is "01234" and endkey is "0123456789" the number "012346" is not a
valid match.
Hope that makes sense!
John
On 24 Jul 2010, at 20:49, J Chris Anderson wrote:
>
> On Jul 24, 2010, at 12:35 PM, John wrote:
>
>> Hi
>>
>> Thanks to you both for the answers so far. Indeed my setup is far more
>> complex than I have exposed to date but I'm making it into bite sized chunks
>> around the Use Cases that I think are the more challenging for me.
>>
>> Although your answers were useful they don't quite hit the mark and that's
>> probably because I didn't explain my problem well enough to start with!
>>
>> The database will contain entries from multiple lists (many thousands
>> perhaps) so the _id will never be unique on a telephone number. Perhaps this
>> might work though:
>>
>> GET /database/<list _id>#0123456789
>>
>> or I could just keep the _id as a uuid and move this problem (find by list
>> id and number) to the view.
>>
>
> for now I'd say just go with uuids and you can have a view by telephone
> number for direct (or starts_with) lookups.
>
>> The view by list wont work for me. I need to be able to query the view with
>> something like:
>>
>> GET /database/_design/portability/_view/NP?key=0123456789&list=<_id of list>
>>
>> In fact in some cases the problem is more complex than this as I need to
>> search for "widest match":
>>
>> GET /database/_design/portability/_view/NP?key=0123456789&list=<_id of
>> list>&min_width=5
>>
>> which would return the widest match in:
>>
>> 0123456789
>> 012345678
>> 01234567
>> 0123456
>> 012345
>> 01234
>>
>>
>> I even have another use case where I need to do a STARTS_WITH e.g. provide a
>> key of 01234 and return true if there are any numbers that start 01234.
>>
>
> this is easy. have a view like:
>
> function(doc) {
> emit([doc.list_id, doc.number], null)
> }
>
> Then you can query with
>
> ?startkey=["mylist", "012"]&endkey=["mylist", "013"]
>
> to get everything with a prefix of "012" in the "mylist" list. you can mess
> around with the endkey_inclusive (or is it inclusive_endkey) = true / false
> to not get the exact number "013" in your result set.
>
> from this technique you can see how you could do starts-with against just
> phone numbers also, with a view like
>
> function(doc_ {
> emit(doc.number, null)
> }
>
> Note I have telephone numbers as strings in this example as a regular number
> 012 is the same as 12.
>
>> This is a typical telecom problem and it would be good to document a Design
>> Pattern for this Use Case. In fact there's a discussion for another day on
>> how/where we could document this patterns and get peer reviews on them.
>>
>> Thanks again
>>
>> John
>>
>> On 24 Jul 2010, at 19:15, J Chris Anderson wrote:
>>
>>>
>>> On Jul 24, 2010, at 7:41 AM, [email protected] wrote:
>>>
>>>> Hello,
>>>>
>>>> 1/ it's a little hard to answer this question, your setup is certainly a
>>>> little more complex than what you expose in your email :-) However
>>>> thousands of documents are gracefuly handled by CouchDB.
>>>>
>>>> 2/ At first sight your documents will look like :
>>>> { "_id": 0123456789 , "list": "mylist", "type": "NP", "status":"portedIn",
>>>> "operatorId":1234 }
>>>>
>>>> That way you can query your document by phone number :
>>>>
>>>> GET /database/0123456789
>>>>
>>>> and have all documents belonging to the list "mylist" by creating a view
>>>> that emits the "list" field :
>>>>
>>>> function (doc) {
>>>> if ( doc.list && doc.type == "NP" ) {
>>>> emit (doc.list,null);
>>>> }
>>>> }
>>>>
>>>> and fetching them with something like :
>>>>
>>>> GET /database/_design/portability/_view/NP?key="mylist"&include_docs=true
>>>>
>>>> 3/ When updating a document : the document is of course immediately
>>>> available. However the view index won't be updated. In CouchDB view
>>>> indexes are rebuilt on view query (not on document update). When you'll
>>>> query CouchDB "give me all the documents of the view NP", Couch will take
>>>> all documents that have changed (added, updated, deleted) since the last
>>>> time you asked Couch for the view, and will update indexes accordingly.
>>>> You have the option of fetching the view without rebuilding the index,
>>>> with the "stale" parameter, but in this case, of course, you won't see the
>>>> changes. During the rebuilt of the index, subsequent view queries are
>>>> queued until the index is up to date.
>>>>
>>>> 4/ I setup CouchDB to parse network logs. A view took something like 25
>>>> minuts for 100 millions documents, on a Dell PowerEdge 2950 Xen Virtual
>>>> Machine with two dedicated processors and 4gigs ram. Numbers can heavily
>>>> vary according to the complexity of the view, so it's always hard (and
>>>> dangerous) to give numbers. Moreover my indexes were not only numbers, but
>>>> also strings.
>>>>
>>>
>>> this is a good response. I'd only follow up to say that there are some
>>> techniques you can use to further tune view-generation performance. one:
>>> keysize and entropy can make a big difference. the view by list, as above,
>>> looks pretty good on that front.
>>>
>>> CouchDB can also be configured to store view indexes on a separate disk
>>> from the database file, which can reduce IO contention if you are at the
>>> edge of what your hardware can do.
>>>
>>> Also, there is the option to query views with stale=ok, which will return a
>>> query based on the latest snapshot, with low latency, so clients aren't
>>> blocked waiting for generation to complete. then you can use a cron-job
>>> with a regular view query and limit=1 to keep the index up to date. so
>>> clients always see a fairly recent snapshot, with low latency.
>>>
>>>>
>>>> What you should be aware of is that CouchDB requires maintenance tasks to
>>>> keep great performances, it's called "compact" and should be run on
>>>> databases (to rebuilt the db file that is append-only) and on databases
>>>> views (to rebuild the index file that is append-only). During the compact,
>>>> database is still available but performances are degraded (from my
>>>> personnal experience).
>>>> Also, a new replication engine is in the pipe and should greatly improve
>>>> the replication experience.
>>>>
>>>>
>>>> Mickael
>>>>
>>>> ----- Mail Original -----
>>>> De: "John" <[email protected]>
>>>> À: [email protected]
>>>> Envoyé: Samedi 24 Juillet 2010 11h37:56 GMT +01:00 Amsterdam / Berlin /
>>>> Berne / Rome / Stockholm / Vienne
>>>> Objet: Large lists of data
>>>>
>>>> Hi
>>>>
>>>> I'm currently evaluating couchdb as a candidate to replace the relational
>>>> databases as used in our Telecom Applications.
>>>> For most of our data I can see a good fit and we already expose our
>>>> service provisioning as json over REST so we're well positioned for a
>>>> migration.
>>>> One area that concerns me though is whether this technology is suitable
>>>> for our list data. An example of this is Mobile Number Portability where
>>>> we have millions of rows of data representing ported numbers with some
>>>> atrributes against each.
>>>>
>>>> We use the standard Relational approach to this and have an entries table
>>>> that has a foreign key reference to a parent list.
>>>>
>>>> On our web services we do something like this:
>>>>
>>>> Create a List:
>>>>
>>>> PUT /cie-rest/provision/accounts/netdev/lists/mylist
>>>> { "type": "NP"}
>>>>
>>>> To add a row to a list
>>>> PUT /cie-rest/provision/accounts/netdev/lists/mylist/entries/0123456789
>>>> { "status":"portedIn", "operatorId":1234}
>>>>
>>>> If we want to add a lot of rows we just POST a document to the list.
>>>>
>>>> The list data is used when processing calls and it requires a fast lookup
>>>> on the entries table which is obviously indexed.
>>>>
>>>> Anyway, I'd be interested in getting some opinions on:
>>>>
>>>> 1) Is couchdb the *right* technology for this job? (I know it can do it!)
>>>>
>>>> 2) I presume that the relationship I currently have in my relational
>>>> database would remain the same for couch i.e. The entry document would ref
>>>> the list document but maybe there's a better way to do this?
>>>>
>>>> 3) Number portability requires 15 min, 1 hour and daily syncs with a
>>>> central number portability database. This can result in bulk updates of
>>>> thousands of numbers. I'm concerned with how long it takes to build a
>>>> couchdb index and to incrementally update it when the number of changes is
>>>> large (Adds/removes).
>>>> What does this mean to the availability of the number? i.e. Is the entry
>>>> in the db but its unavailable to the application as it's entry in the
>>>> index hasnt been built yet?
>>>>
>>>> 4) Telephone numbers like btrees so the index building should be quite
>>>> fast and efficient I would of thought but does someone have anything more
>>>> concrete in terms of how long it would take typically? I think that the
>>>> bottleneck is the disk i/o and therefore it may be vastly different
>>>> between my laptop and one of our beefy production servers but again I'd be
>>>> interested in other peoples experience.
>>>>
>>>> Bit of a long one so thanks if you've read it to this point! There's a lot
>>>> to like with couchdb (esp the replication for our use case) so I'm hoping
>>>> that what i've asked above is feasible!
>>>>
>>>> Thanks
>>>>
>>>> John
>>>>
>>>>
>>>
>>
>
