Sabine, > Am 06.08.2015 um 14:49 schrieb Sabine Manaa <manaa.sab...@gmail.com>: > > 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/ > <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 <manaa.sab...@gmail.com > <mailto:manaa.sab...@gmail.com>>: > > > > 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 > >> > >> <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 > >> > >> <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 > >> <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 > >> > >> <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. > >> > >> > >> > >> > >> ________________________________ > >> If you reply to this email, your message will be added to the discussion > >> below: > >> http://forum.world.st/MongoDB-console-commands-query-embedded-indexed-fields-tp4840882p4840888.html > >> > >> <http://forum.world.st/MongoDB-console-commands-query-embedded-indexed-fields-tp4840882p4840888.html> > >> To start a new topic under Pharo Smalltalk Users, email [hidden email] > >> To unsubscribe from MongoDB: console commands? query embedded indexed > >> fields?, click here. > >> 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.
