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Introspection query does not work in MongoDB

Hi All, We have Denodo 8 on Windows Server. We installed mongodb-customwrapper according to document. (https://community.denodo.com/docs/html/document/denodoconnects/6.0/Denodo%20MongoDB%20Custom%20Wrapper%20-%20User%20Manual) No problem connecting or uploading data from MongoDB. But Introspection query not working. 1- I'm submitting the query in another tool ![https://ibb.co/5jLYp8y](http://) 2- I fill fields in denodo ![https://ibb.co/DVzTs4d](https://ibb.co/DVzTs4d) 3- But the query didn't work. Uploaded all data ![http://ibb.co/jZk2z4Q](http://ibb.co/jZk2z4Q) I also tried just by filling in the introspection query section. Result is the same What is the problem ?
user
13-12-2021 09:15:01 -0500

1 Answer

Hi, The **"introspection query"** option in the MongoDB Custom Wrapper, is used for introspecting the data source (i.e. inferring the fields of the base view). It will only be executed during the base view creation process to determine which are the fields in the MongoDB side that should be converted to columns in the base view. Once the base view is defined, the introspection query is not part of the execution process anymore. So any filters established there will not be applied to every execution of the base view. Hence, the behavior you are experiencing is the expected one. However, if you want to retrieve specific data from the MongoDB server, you could create a [selection view](https://community.denodo.com/docs/html/browse/8.0/en/vdp/administration/creating_derived_views/creating_selection_views/creating_selection_views#creating-selection-views) on top of the base view created and apply the required filter condition using the where clause. For more information about the MongoDB Custom Wrapper, you could refer to the [Denodo MongoDB Custom Wrapper](https://community.denodo.com/docs/html/document/denodoconnects/8.0/en/Denodo%20MongoDB%20Custom%20Wrapper%20-%20User%20Manual) User Manual. Hope this helps!!
Denodo Team
16-12-2021 08:35:32 -0500
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