> Am 08.08.2015 um 10:38 schrieb Sabine Manaa <manaa.sab...@gmail.com>:
>
> Hi Norbert,
>
> lol, I had to google that: https://en.wikipedia.org/wiki/Heisenbug
> funny but that's it. It is always a good feeling when I know what the reason
> for a certain behavior is.
> Now I can proceed with the implementation of the search functionality.
>
> no, in Mongo I don't store the back references, they are created when the
> objects are instantiated in pharo.
> Wouldn't you do it like this? What is the background for your question?
>
The background is that there is a difference between an in-memory graph and a
persisted one. So storing forth and backreferences is asking for trouble.
Having back references being transient and reestablishing them on
materialization is a good way of having the best of both world.
Norbert
> Regards
> Sabine
>
> 2015-08-07 15:06 GMT+02:00 NorbertHartl [via Smalltalk] <[hidden email]>:
>>
>>> Am 07.08.2015 um 14:53 schrieb Sabine Manaa <[hidden email]>:
>>>
>>> Hi Norbert, Hi Phil,
>>>
>>> thanks for your help! Now I know what the problem is/was. :-)))
>>>
>>> The query was right, the index was used, all is fine.
>>>
>>> BUT:
>>> I used an inspector to look at the query's result and opening the inspector
>>> forced to load all the other objects which belong to the object found.
>>> Explanation: I have a person which has N trips with N receipts, all with
>>> back pointers. Opening an Inspector with one trip loads its person and all
>>> other trips of this person hahaha. The magritte description isLazy but the
>>> inspector forced the loading of the objects in the VOMongoRepository at
>>> first time after image starting.
>>>
>>> Time millisecondsToRun: [(RKATrip selectMany: {
>>> 'receipts.receiptDescription' -> 'a' } asDictionary) size] 764 .
>>> Time millisecondsToRun: [(RKATrip selectMany: {
>>> 'receipts.receiptDescription' -> 'a' } asDictionary) inspect] 17234
>>>
>>> So, I messed around with myself.
>> Well, we call this an inversed Heisenbug, don't we? :) That is a problem we
>> should be aware when using proxy implementations and tools like gt tools. It
>> is very likely that a powerful tool will inquire special information on a
>> proxy that will trigger it.
>>
>>> Currently I do not have so much data but I hope in future there will be a
>>> lot and I want the application prepared for that.
>> It depends on the tool and your model. Are you storing those backreferences
>> in mongo as well?
>>
>> Norbert
>>
>>> BTW: I found this nice document:
>>> https://ci.inria.fr/pharo-contribution/job/EnterprisePharoBook/ws/Voyage/Voyage.pdf
>>> I was mentioned there, thanks! Esteban, if you want, you could change my
>>> name, I married and changed my name to Manaa.
>>>
>>> have a nice weekend
>>> Sabine
>>>
>>> 2015-08-06 15:36 GMT+02:00 NorbertHartl [via Smalltalk] <<a
>>> href="x-msg://13/user/SendEmail.jtp?type=node&node=4841464&i=0"
>>> target="_top" rel="nofollow" link="external" class="">[hidden email]>:
>>>
>>>> Sabine,
>>>>
>>>>> Am 06.08.2015 um 14:49 schrieb Sabine Manaa <[hidden email]>:
>>>>>
>>>>> Norbert,
>>>>>
>>>>> I have to come back to your answer.
>>>>>
>>>>> With the .explain option, I can see, how performance is with and without
>>>>> index on the _mongo console_.
>>>>> As an example, I see: with index only 2 objects scanned, without: 200.
>>>>> Performance is perfect with index.
>>>>>
>>>>> But _from smalltalk_, it seems to iterate over all objects, also with the
>>>>> index set. Slow.
>>>>>
>>>>> You wrote: "The index will be selected automatically." It seems that it
>>>>> does not.
>>>>
>>>> Usually it does.
>>>>
>>>>> My question:
>>>>> MongoQuery has an attribute named "where" which is filled with the
>>>>> mentioned "receipts.receiptDescription".
>>>>> Because of the name of this attribute "where" and the slow performance, I
>>>>> assume that the mongo classes use the $where command:
>>>>>
>>>>> http://docs.mongodb.org/manual/reference/operator/query/where/
>>>>>
>>>>> Is this right?
>>>>>
>>>>> In this case with the statement
>>>>> Trip selectMany: { 'receipts.receiptDescription' -> 'Tankquittung' }
>>>>> asDictionary
>>>>> the index would not be set automatically.
>>>>>
>>>>> "The $where provides greater flexibility, but requires that the database
>>>>> processes the JavaScript expression or function for each document in the
>>>>> collection. "
>>>>>
>>>>> Then my question is if the mongo classes support database queries with
>>>>> index and if yes, how.
>>>>>
>>>>> I am very interested in your opinion and I think other users should have
>>>>> the same requirements (querying indexed variables) - how did they solve
>>>>> this?
>>>> The handling of indexes needs to be automatic. The rule of thumb is that
>>>> if you use where clause like b = , c = , a= than you need an compound
>>>> index in the same order being index(b,c,a). This is handled by the
>>>> database when it analyzes the query it tries to find an appropriate index.
>>>> Or seeing it from the other side: If you issue a query with index and the
>>>> index does not fit the query it is a problem anyway. Are you sure you have
>>>> only this one thing in the where query?
>>>>
>>>> I use e.g.
>>>>
>>>> COInstalledApp selectOne: {
>>>> 'device.id' -> aString.
>>>> 'application.__id' -> anApplication voyageId } asDictionary
>>>>
>>>> on a collection that has approx. 1 Mio. entires and it is fast. I didn't
>>>> check with explain but I'll do if I find time :)
>>>>
>>>> If I were you I would step in the debugger down to the Voyage part after
>>>> serialization. Then you have the exact Dictionary that is used to send to
>>>> mongo. You can then use this query to do an "explain" on it and that
>>>> should show you something. Another thing you can try (although I don't
>>>> think makes any difference) is to use the non-javascript query variant.
>>>> That would be
>>>>
>>>> Trip selectMany: {
>>>> 'receipts' -> {
>>>> 'receiptDescription' -> 'Tankquittung' } asDictionary }
>>>> asDictionary
>>>>
>>>> Norbert
>>>>
>>>>> Regards
>>>>> Sabine
>>>>>
>>>>>
>>>>> 2015-08-04 14:47 GMT+02:00 Sabine Manaa <[hidden email]>:
>>>>>
>>>>> >
>>>>> > Hi Norbert,
>>>>> >
>>>>> > I didn't want to use "use database" for queries but for defining the
>>>>> > index from within smalltalk. But if creating indexes is not supported,
>>>>> > I will set the indexes within the mongo console.
>>>>> >
>>>>> > The explain option is very helpful I did not know this.
>>>>> >
>>>>> > Your answer was very helpful for me, thanks a lot!
>>>>> > Sabine
>>>>> >
>>>>> >
>>>>> >
>>>>> > 2015-08-04 10:42 GMT+02:00 NorbertHartl [via Smalltalk] <[hidden
>>>>> > email]>:
>>>>> >>
>>>>> >> Sabine,
>>>>> >>
>>>>> >> Am 04.08.2015 um 07:08 schrieb Sabine Manaa <[hidden email]>:
>>>>> >>
>>>>> >> Hi,
>>>>> >>
>>>>> >> I have 2 questions concerning use of mongoDB classes:
>>>>> >> 1) how can I send mongo console commands directly from smalltalk
>>>>> >> 2) how to query on an embedded collection with an index
>>>>> >>
>>>>> >> Model:
>>>>> >> I have trips and each trip has an embedded collection of N receipts
>>>>> >> like
>>>>> >> this:
>>>>> >> { "tripName" : "trip 1",
>>>>> >> {"receipts" : [
>>>>> >> {"receiptDescription" : "receipt 1" }
>>>>> >> {"receiptDescription" : "receipt 2" }
>>>>> >> {"receiptDescription" : "receipt 3" } ],
>>>>> >> }
>>>>> >>
>>>>> >> Index:
>>>>> >> For quick search, I created an index on the embeded[1] receipts with
>>>>> >> this
>>>>> >> command at the mongoDB console in a terminal (NOT in smalltalk)
>>>>> >> (mongo console starts with mongo in the MongoDB/bin dir):
>>>>> >>
>>>>> >> db.Trips.createIndex({"receipts.receiptDescription":1})
>>>>> >>
>>>>> >> with a command like this in the mongoDB console
>>>>> >>
>>>>> >> db.Trips.find({"receipts.receiptDescription":"receipt 1"})
>>>>> >>
>>>>> >> I get the resulting receipt.
>>>>> >>
>>>>> >> Before, I have to set the database with "use {databasename}" in thr
>>>>> >> mongodb
>>>>> >> console
>>>>> >>
>>>>> >> My questions:
>>>>> >> 1) how can I send mongo console commands directly from smalltalk, e.g.
>>>>> >> use
>>>>> >> database, set index etc.
>>>>> >>
>>>>> >>
>>>>> >> I don't know why you want to use "use database". For queries you don't
>>>>> >> need this because you choose the database and collection by using the
>>>>> >> smalltalk classes. You can look there if something you need exists.
>>>>> >> Creating indexes is not yet supported. I want to do that myself. As
>>>>> >> always there seems to be to less people implementing stuff like that.
>>>>> >>
>>>>> >> Is this possible?
>>>>> >> I did not succeed with the mongo command: method, it always returns
>>>>> >> "no such
>>>>> >> cmd".
>>>>> >>
>>>>> >> 2) how can I search for a receipt which is indexed as described from
>>>>> >> smalltalk?
>>>>> >>
>>>>> >>
>>>>> >> A simple
>>>>> >>
>>>>> >> Trip selectMany: { 'receipts.receiptDescription' -> 'Tankquittung' }
>>>>> >> asDictionary
>>>>> >>
>>>>> >> should do. You can use just the nested properties form. The index will
>>>>> >> be selected automatically. If you are not sure about queries read
>>>>> >> about explain [1] to optimize that stuff.
>>>>> >>
>>>>> >> [1]
>>>>> >> http://docs.mongodb.org/manual/reference/method/cursor.explain/#cursor.explain
>>>>> >>
>>>>> >> Norbert
>>>>> >>
>>>>> >>
>>>>> >> I did not succeed with the description [2] I am not sure if it is
>>>>> >> covered by
>>>>> >> it.
>>>>> >>
>>>>> >> Regards
>>>>> >> Sabine
>>>>> >>
>>>>> >>
>>>>> >> [1]
>>>>> >> http://docs.mongodb.org/manual/core/index-multikey/#index-arrays-with-embedded-documents
>>>>> >> [2] http://smallworks.eu/web/blog/2013-07-18-Voyage-advanced-queries
>>>>> >>
>>>>> >>
>>>>> >>
>>>>> >> --
>>>>> >> View this message in context:
>>>>> >> http://forum.world.st/MongoDB-console-commands-query-embedded-indexed-fields-tp4840882.html
>>>>> >> Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.
>>>>> >>
>>>>> >>
>>>>> >>
>>>>> >>
>>>>> >> ________________________________
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>>>>> >> NAML
>>>>> >
>>>>> >
>>>>> >
>>>>> > ________________________________
>>>>> > View this message in context: Re: MongoDB: console commands? query
>>>>> > embedded indexed fields?
>>>>> >
>>>>> > Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.
>>>
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>>
>>
>> View this message in context: Re: MongoDB: console commands? query embedded
>> indexed fields?
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