NDBI040: Big Data Management and NoSQL Databases

Transcription

1 NDBI040: Big Data Management and NoSQL Databases h p:// Prac cal Class 8 MongoDB Mar n Svoboda svoboda@ksi.mff.cuni.cz Charles University in Prague, Faculty of Mathema cs and Physics Czech Technical University in Prague, Faculty of Electrical Engineering

2 Data Model Database system structure Instance databases collec ons documents Database Collec on Collec on of documents, usually of a similar structure Document MongoDB document = one JSON object I.e. even a complex JSON object with other recursively nested objects, arrays or values Unique immutable iden fier Field name restric ons:, $,. NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

3 CRUD Opera ons Overview Inserts a new document into a collec on Modifies an exis ng document / documents or inserts a new one Deletes an exis ng document / documents Finds documents based on filtering condi ons Projec on and / or sor ng may be applied too NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

4 Mongo Shell Connect to our NoSQL server SSH / PuTTY and SFTP / WinSCP nosql.ms.mff.cuni.cz:42222 Start mongo shell Try several basic commands Displays a brief descrip on of database commands Closes the current client connec on NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

5 Databases Switch to your database Use your login name as a name for your database List all the exis ng databases Your database will be created later on implicitly NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

6 Collec ons Create a new collec on for actors Suitable when crea ng collec ons with specific op ons since collec ons can also be created implicitly List all collec ons in your database NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

7 Insert Opera on Inserts a new document / documents into a given collec on db. collection. insert ( document [ document ], options ), Parameters Document: one or more documents to be inserted Op ons NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

8 Insert Opera on Insert a few new documents into the collec on of actors Retrieve all documents from the collec on of actors NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

9 Update Opera on Modifies / replaces an exis ng document / documents db. collection. update ( query, update, options ) Parameters Query: descrip on of documents to be updated Update: modifica on ac ons to be applied Op ons Update operators,,,,,,,,,, NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

10 Update Opera on Update the document of actor Ivan Trojan At most one document is updated Its content is replaced with a new value Check the current content of the document NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

11 Update Opera on Use method to insert a new actor Inserts a new document when behavior was enabled and no document could be updated NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

12 Update Opera on Try to modify the document iden fier of an exis ng document Your request will be rejected since document iden fiers are immutable NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

13 Update Opera on Update the document of actor Ivan Trojan Update mul ple documents at once NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

14 Save Opera on Replaces an exis ng / inserts a new document db. collection. save ( document, options ) Parameters Document: document to be modified / inserted Op ons NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

15 Save Opera on Use method to insert new actors Document iden fier must not be specified in the query or must not yet exist in the collec on Use method to update actor Ivan Trojan Document iden fier must be specified in the query and must exist in the collec on NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

16 Remove Opera on Removes a document / documents from a given collec on db. collection. remove ( query, options ) Parameters Query: descrip on of documents to be removed Op ons NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

17 Remove Opera on Remove selected documents from the collec on of actors Remove all the documents from the collec on of actors NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

18 Sample Data Insert the following actors into your emp ed collec on NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

19 Find Opera on Selects documents from a given collec on db. collection. find ( query, projection ) Parameters Query: descrip on of documents to be selected Projec on: fields to be included / excluded in the result NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

20 Querying Execute and explain the meaning of the following queries NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

21 Querying Execute and explain the meaning of the following queries NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

22 Index Structures Mo va on Full collec on scan must be conducted when searching for documents unless an appropriate index exists Primary index Unique index on values of the _id field Created automa cally Secondary indexes Created manually for values of a given key field / fields Always within just a single collec on NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

23 Index Structures Secondary index crea on db. collection. createindex ( keys, options ) Defini on of keys (fields) to be involved { field : 1-1 text hashed 2d 2dsphere }, NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

24 Index Structures Index types, standard ascending / descending value indexes Both scalar values and embedded documents can be indexed hash values of a single field are indexed basic full-text index points in planar geometry points in spherical geometry NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

25 Index Structures Index forms One key / mul ple keys (composed index) Ordinary fields / array fields (mul -key index) Index proper es Unique duplicate values are rejected (cannot be inserted) Par al only certain documents are indexed Sparse documents without a given field are ignored TTL documents are removed when a meout elapses Just some type / form / property combina ons can be used! NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

26 Index Structures Execute the following query and study its execu on plan Create a mul key index for movies of actors Examine the execu on plan once again NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

27 MapReduce Executes a MapReduce job on a selected collec on db. collection. mapreduce ( map function, reduce function, options ) Parameters Map: JavaScript implementa on of the Map func on Reduce: JavaScript implementa on of the Reduce func on Op ons NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

28 MapReduce Map func on Current document is accessible via is used for emissions Reduce func on Intermediate key and values are provided as arguments Reduced value is published via Op ons : only matching documents are considered : they are processed in a specific order : at most a given number of them is processed : output is stored into a given collec on NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

29 MapReduce: Example Count the number of movies filmed in each year, star ng in 2005 NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

30 MapReduce Implement and execute the following MapReduce jobs Find a list of actors (their names sorted alphabe cally) for each year (they were born) Use op on Calculate the overall number of actors for each movie Use op on once again NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB

31 References Documenta on h ps://docs.mongodb.com/v3.2/ NDBI040: Big Data Management and NoSQL Databases Prac cal Class 8: MongoDB