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From Jan Lehnardt <...@apache.org>
Subject Re: Updating views on save
Date Wed, 30 Apr 2008 11:08:10 GMT

On Apr 29, 2008, at 23:13, Guby wrote:
> Hm...
> On my server I just noticed CouchDB had started 14 instances of the  
> DbUpdateNotificationProcess!
> Is this normal, and in case, why so many? And why do they all keep  
> running when the CouchDB is somewhat idle and doesn't need them at  
> all?

CouchDB should only start one instance. It will kill and spawn a new
one in case of a problem. Maybe you have old instances of the
daemon that decided not to die and CouchDB happily spawned
fresh copies. What's the state of all the processes? Do they all
receive updates?

Cheers
Jan
--

>
>
> Best regards
> Sebastian
>
>
>
> On Apr 28, 2008, at 1:55 PM, Guby wrote:
>
>> Added to wiki: http://wiki.apache.org/couchdb/RegeneratingViewsOnUpdate
>> Edit as you see fit.
>>
>> S
>>
>>
>> On Apr 28, 2008, at 1:14 PM, Guby wrote:
>>
>>> Sure!
>>> That makes more sense than having it here in the mailinglist :)
>>>
>>> S
>>>
>>> On Apr 28, 2008, at 12:58 PM, Jan Lehnardt wrote:
>>>
>>>>
>>>> On Apr 28, 2008, at 17:18, Guby wrote:
>>>>> I am very happy with the way this discussion turned out!
>>>>> Now I have written a tiny ruby script that updates the views for  
>>>>> every tenth document update and at most once every second under  
>>>>> heavy updates.
>>>>> Here on my development machine it uses about 1.2 mb of ram, and  
>>>>> I can live with that.
>>>>>
>>>>> I'll include it here in case somebody reads this discussion in  
>>>>> the future and needs a similar script.
>>>>
>>>> Would you mind putting it on the Wiki? For the obvious benefits :)
>>>>
>>>> Good work there,
>>>>
>>>> Cheers
>>>> Jan
>>>> --
>>>>
>>>>
>>>>>
>>>>>
>>>>> Thanks again for all the help and for a great database!
>>>>>
>>>>> Best regards
>>>>> Sebastian
>>>>>
>>>>>
>>>>> **********************************
>>>>>
>>>>> CONFIG: couch.ini:
>>>>> add line:
>>>>> DbUpdateNotificationProcess=/PATH/TO/view_updater.rb
>>>>>
>>>>> **********************************
>>>>>
>>>>> SCRIPT: view_updater.rb
>>>>>
>>>>> #!/usr/bin/ruby
>>>>>
>>>>> ###
>>>>> # CONF
>>>>> ###
>>>>>
>>>>> # The smallest amount of changed documents before the views are  
>>>>> updated
>>>>> MIN_NUM_OF_CHANGED_DOCS = 10
>>>>>
>>>>> # URL to the DB on the CouchDB server
>>>>> # Only supports one database at the moment as that is what I need
>>>>> # Should be easy to improve for several databases if needed
>>>>> URL = "http://localhost:5984/kleio"
>>>>>
>>>>> # Set the minimum pause between calls to the database
>>>>> PAUSE = 1 # seconds
>>>>>
>>>>> # One for each design document
>>>>> VIEWS = ["feed/to_check",
>>>>>     "feed_entries/list_for_user_by_feed",
>>>>>     "subscription/number_of_subscriptions",
>>>>>     "subscription_requests/request",
>>>>>     "user/by_email",
>>>>>     "couch_object_has_many_relations/related_documents"]
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> ###
>>>>> # "MAIN LOOP"
>>>>> ###
>>>>>
>>>>> run = true
>>>>> number_of_changed_docs = 0
>>>>>
>>>>> threads = []
>>>>>
>>>>> # Updates the views
>>>>> threads << Thread.new do
>>>>>
>>>>> while run do
>>>>>
>>>>> if number_of_changed_docs >= MIN_NUM_OF_CHANGED_DOCS
>>>>>
>>>>>  number_of_changed_docs = 0
>>>>>
>>>>>  VIEWS.each do |view|
>>>>>    `curl #{URL}/_view/#{view}?count=0`
>>>>>  end
>>>>>
>>>>> end
>>>>>
>>>>> sleep PAUSE
>>>>>
>>>>> end
>>>>>
>>>>> end
>>>>>
>>>>> # Receives the update notification from CouchDB
>>>>> threads << Thread.new do
>>>>>
>>>>> while run do
>>>>>
>>>>> update_call = gets
>>>>>
>>>>> # When CouchDB exits the script gets called with
>>>>> # a never ending series of nil
>>>>> if update_call == nil
>>>>>  run = false
>>>>> else
>>>>>  number_of_changed_docs += 1
>>>>> end
>>>>>
>>>>> end
>>>>>
>>>>> end
>>>>>
>>>>> # Good bye
>>>>> threads.each {|thr| thr.join}
>>>>>
>>>>>
>>>>
>>>
>>
>


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