CouchDB

1. CouchDB - Sai Divya Panditi - Priyanka Yechuri

2. Overview • Introduction • SQL vs CouchDB • CouchDB Features • CouchDB Core API • Futon • Security • Application

3. Overview • Demo • Code • Advantages • DisAdvantages • Iris Couch • Conclusion • References

4. Introduction • Created By : Damien Katz • Year : 2005 • Language : Erlang • License : Apache Software Foundation(2008)

5. Introduction... • NoSQL Database .....Uses Map/Reduce queries written in javascript

6. NoSQL Databases • Schema-Free • Distributed • Open Source • Horizontally Scalable • Easy Replication Support

7. NoSQL Timeline

8. Document-Oriented DBMS • Data is stored in documents ......and not in relations like an RDBMS

9. SQL vs CouchDB

10. CouchDB Features • Data Representation - Using JSON • Interaction - Futon / CouchDB API • Querying - Map / Reduce • Design Documents - Application code(Language : Javascript) • Documents can have attachments

11. JSON • Stands for Javascript Object Notation • Derived from Javascript scripting language • Used for representing simple data structures and associative arrays

12. JSON..... • Example: { • "firstName": "John", • "lastName": "Smith", • "age": 25, • "phoneNumber": [ • { • "type": "home", • "number": "212 555-1234" • }, • { • "type": "fax", "number": "646 555-4567" • } ] • }

13. CouchDB Core API (Command Line Utility ) • Server API • Database API • Document API • Replication API

14. HTTP API • Messages are self-described via HTTP Headers and HTTP Status Codes. • URIs identify resources. • HTTP Methods define operations on the resources.

15. HTTP Request Methods

16. HTTP Status Codes

17. Curl Command - Server API • Command to check if CouchDB is working at all? curl http://127.0.0.1:5984/ • Response : {"couchdb":"Welcome","version":"0.10.1"}

18. Curl Command - Database API • Command to get a list of Databases : curl -X GET http://127.0.0.1:5984/_all_dbs • Command to create a Database : curl -X PUT http://127.0.0.1:5984/DB_name • Curl's -v option : curl -vX PUT http://127.0.0.1:5984/DB_name • Command to destroy a Database : curl -X DELETE http://127.0.0.1:5984/DB_name

19. Curl Command - Document API • Command to create a document : curl -X PUT http://127.0.0.1:5984/albums/ 6ert2gh45ji6h6tywe324743rtbhgtrg \ -d '{"title":"abc","artist":"xyz"}' • Command to get a UUID : curl -X GET http://127.0.0.1:5984/_uuids • Command to retrieve a Document : curl -X GET http://127.0.0.1:5984/albums/ 6ert2gh45ji6h6tywe324743rtbhgtrg

20. Curl Command - Document API • Command for attachments : curl -vX PUT http://127.0.0.1:5984/albums/ 6ert2gh45ji6h6tywe324743rtbhgtrg/ \ artwork.jpg?rev=2-2739352689 --data-binary @artwork.jpg -H "Content-Type: image/jpg" • To view the image in the browser, URL is : http://127.0.0.1:5984/albums/6ert2gh45ji6h6 tywe324743rtbhgtrg/artwork.jpg

21. Curl Command-Replication API • Command to replicate a Database : curl -vX POST http://127.0.0.1:5984/ _replicate \ -d '{"source":"albums","target": "albums_replica"}'

22. Futon • Built-in admin interface • Access to all CouchDB features • Create and Destroy databases • Create, View and Edit Documents • Compose and run Map / Reduce Views • Replicate a Database

23. Futon Interface Demo...

24. Design Documents • Contains application code • They are like normal json documents but prefixed by _design/ • CouchDB looks for views and other application functions here...

25. Views • Used for extracting data we need for a specific purpose • Example : function(doc){ if(doc.Bname) { emit(doc.id,doc.Bname); } }

26. View Functions... • Map - single parameter - doc • emit(key,value) - built-in function • Results of emit() are sorted by key • We query the views to produce the desired result • When we query a view, it's run on every document in the database for which view is defined • View result is stored in a B-tree

27. View Functions… • B-tree for the view is built only once and all the subsequent queries will just read the B-tree instead of executing the map function again • Used to find documents by any value or structure that resides in them • Using the URI, we can retrieve the exact data we need. For Example : /books/_design/docs/_view/by_Bname?key="Circuits"

28. Map Functions • For Example : Consider the following documents

29. Map Functions… • Output :

30. Map Functions… • Map Function : map:function(doc) { emit(doc.Bname, doc.id); } • Output :

31. Reduce Function • This function operates on the sorted rows emitted by map view functions. • Predefined Reduce Functions: • _sum, _count etc. • Example: • function(keys,values){ • return sum(values); //gives aggregate values • }

32. Security • Database Admins • Validation Functions

33. Database Admin Demo…

34. Validation Function • Uses the function validate_doc_update(). • If the validation function raises an exception, the update is denied else the updates are accepted. • Document validation is optional.

35. Who uses CouchDB?

36. Application • GSUBooks.com

38. Code - add.js add.js: $(document).ready( function() { //Event handler crud stuff $('input#addId').click(function(e) { if ($('#bookId').val().length == 0) { return; } var bookdoc = { booknm: $('#bookId').val(), authornm: $('#authorId').val(), category: $('#categoryId').val(), edition: $('#editionId').val(),quantity: $('#quantityId').val() }

39. Code - add.js... • db.saveDoc(bookdoc, { success: function(resp) • { checkList(); //refreshes the database with new book } • });

40. Code-delete.js delete.js $(document).ready ( function() { $('input#borrowId').click(function(e) { if ($('#idId').val().length == 0) { return; } var bookdoc = { _id: $('#idId').val(), _rev: $('#revId').val() } db.removeDoc(bookdoc, { success: function(resp) {

41. Code-delete.js checkList(); //refreshes the database with the remaining books alert("Book has been borrowed Successfully!!"); }}); clearDocument(); });}); function clearDocument() { $('#idId').val(''); $('#revId').val(''); $('#bookId').val(''); $('#authorId').val(''); $('#categoryId').val(''); $('#editionId').val(''); $('#quantityId').val('');};

42. Code - Update.js • update.js • $(document).ready(function() • { $('input#updateId').click(function(e) • { if ($('#idId').val().length == 0) • { return; }varbookdoc = { • _id: $('#idId').val(), _rev: $('#revId').val(),booknm: $('#bookId').val(),

43. update.js... authornm:$('#authorId').val(), category:$('#categoryId').val(), edition:$('#editionId').val(), quantity:$('#quantityId').val() } db.saveDoc(bookdoc, { success: function(resp) { checkList(); } }); });

44. Code - Display.js display.js $(document).ready(function() { checkList();}); function checkList() { $("table#itemData").empty(); db.view("myfirstDesign/myfirstView", { success: function(data) { $('table#itemData').append('<tr><th><font color="black">Book Name</font></th><th><font color="black">Author Name</font></th><th><font color="black">Category</font></th><th><font color="black">Edition</font></th>

45. Code - Display.js <th><font color="black">Quantity</font></th></tr>'); data.rows.map(function(row) { $('table#itemData').append('<tr><td id="'+row.value._id+'"align="center"><font +row.value.booknm +'</font></td><td align="center"><font color="navy">' +row.value.authornm +'</font></td><td align="center"><font color="navy">' +row.value.category +'</font></td><td align="center"><font color="navy">' +row.value.edition +'</font></td><td align="center"><font color="navy">' +row.value.quantity +'</font></td></tr>'); $('#'+row.value._id).click(function() { $('#idId').val(row.value._id);

46. Code - Display.js $('#revId').val(row.value._rev); $('#bookId').val(row.value.booknm); $('#authorId').val(row.value.authornm); $('#categoryId').val(row.value.category); $('#editionId').val(row.value.edition); $('#quantityId').val(row.value.quantity); return false; }); }); } });}

47. Advantages / DisAdvantages • Features • Not easy to learn especially if the user is familiar with SQL • Security is weak • Temporary views on large datasets are very slow. • Replication of large databases may fail • Documents are quite large as the data is represented using “JSON” format

48. Iris Couch • Cloud CouchDB hosting • Free service

49. Iris Couch Demo…

50. References • CouchDB - The Definitive Guide , J. Chris Anderson, Jan Lehnardt & Noah Slater • Beginning CouchDB, Joe Lennon