CouchDB - Sai Divya Panditi - Priyanka Yechuri
Overview Introduction SQL vs CouchDB CouchDB Features CouchDB Core API Futon Security Application
Overview Demo Code Advantages DisAdvantages Iris Couch Conclusion References
Introduction Created By : Damien Katz Year : 2005 Language : Erlang License : Apache Software Foundation(2008)
Introduction... NoSQL Database.....Uses Map/Reduce queries written in javascript
NoSQL Databases Schema-Free Distributed Open Source Horizontally Scalable Easy Replication Support
NoSQL Timeline
Document-Oriented DBMS Data is stored in documents......and not in relations like an RDBMS
SQL vs CouchDB SQLCouchDB RelationalNon-Relational TablesDocuments with types Rows and ColumnsDocument Fields SQL Query EngineMap / Reduce Engine
CouchDB Features Data Representation - Using JSON Interaction - Futon / CouchDB API Querying - Map / Reduce Design Documents - Application code(Language : Javascript) Documents can have attachments
JSON Stands for Javascript Object Notation Derived from Javascript scripting language Used for representing simple data structures and associative arrays
JSON..... Example: { "firstName": "John", "lastName": "Smith", "age": 25, "phoneNumber": [ { "type": "home", "number": " " }, { "type": "fax", "number": " " } ] }
CouchDB Core API (Command Line Utility ) Server API Database API Document API Replication API
HTTP API Messages are self-described via HTTP Headers and HTTP Status Codes. URIs identify resources. HTTP Methods define operations on the resources.
HTTP Request Methods MethodDescription PUT GET POST DELETE COPY PUT requests are used to create new resources where the URI of the request is different to the resource that is to be created. GET requests are used to request data from the database. POST requests are used to update the existing data, at the same resource the URI is requested from. DELETE requests to delete databases and documents. Copies one resource to another resource.
HTTP Status Codes Status CodeDescription 200 (OK) 201 (Created) 304 (Not Modified) 400 (Bad Request) 404 (Not Found) 405 (Method Not Allowed) 409 (Conflict) 412 (Precondition Failed) 500 (Internal Server Error) The request was successfully processed. The document was successfully created. The document has not been modified since the last update. The syntax of the request was invalid. The request was not found. The request was made using an incorrect request method. The request failed because of a database conflict. could not create a database- a database with that name already exists. The request was invalid and failed, or an error occurred within the CouchDB server.
Curl Command - Server API Command to check if CouchDB is working at all? curl Response : {"couchdb":"Welcome","version":"0.10.1"}
Curl Command - Database API Command to get a list of Databases : curl -X GET Command to create a Database : curl -X PUT Curl's -v option : curl -vX PUT Command to destroy a Database : curl -X DELETE
Curl Command - Document API Command to create a document : curl -X PUT 6ert2gh45ji6h6tywe324743rtbhgtrg \ -d '{"title":"abc","artist":"xyz"}' Command to get a UUID : curl -X GET Command to retrieve a Document : curl -X GET 6ert2gh45ji6h6tywe324743rtbhgtrg
Curl Command - Document API Command for attachments : curl -vX PUT 6ert2gh45ji6h6tywe324743rtbhgtrg/ \ artwork.jpg?rev= H "Content-Type: image/jpg" To view the image in the browser, URL is : tywe324743rtbhgtrg/artwork.jpg
Curl Command- Replication API Command to replicate a Database : curl -vX POST _replicate \ -d '{"source":"albums","target": "albums_replica"}'
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
Futon Interface Demo...
Design Documents Contains application code They are like normal json documents but prefixed by _design/ CouchDB looks for views and other application functions here...
Used for extracting data we need for a specific purpose Example : function(doc){ if(doc.Bname) { emit(doc.id,doc.Bname); } Views
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
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"
Map Functions For Example : Consider the following documents Document-1 id : 1 Bname : Oracle Category : CS Author : abc Edition : 2007 Document-2 id : 2 Bname : Networks Category : CS Author : xyz Edition : 2001 Document-3 id : 3 Bname : Circuits Category : Electronics Author : abcd Edition : 2004 Document-4 id : 4 Bname : AI Category : CS Author : pqrs Edition : 2010
Map Functions… Output : KeyValue 1Oracle 2Networks 3Circuits 4AI
Map Functions… Map Function : map:function(doc) { emit(doc.Bname, doc.id); } Output : AI4 Circuits3 Networks2 Oracle1
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 }
Security Database Admins Validation Functions
Database Admin Demo…
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.
Who uses CouchDB?
Application GSUBooks.com
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() } Code - add.js
Code - add.js... db.saveDoc(bookdoc, { success: function(resp) { checkList(); //refreshes the database with new book } });
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) {
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(''); };
Code - Update.js update.js $(document).ready(function() { $('input#updateId').click(function(e) { if ($('#idId').val().length == 0) { return; } var bookdoc = { _id: $('#idId').val(), _rev: $('#revId').val(), booknm: $('#bookId').val(),
update.js... authornm:$('#authorId').val(), category:$('#categoryId').val(), edition:$('#editionId').val(), quantity:$('#quantityId').val() } db.saveDoc(bookdoc, { success: function(resp) { checkList(); } });
display.js $(document).ready(function() { checkList(); }); function checkList() { $("table#itemData").empty(); db.view("myfirstDesign/myfirstView", { success: function(data) { $('table#itemData').append(' Book Name Author Name <font color="black">Category Edition Code - Display.js
Quantity '); data.rows.map(function(row) { $('table#itemData').append(' ' +row.value.authornm +' ' +row.value.category +' ' +row.value.edition +' ' +row.value.quantity +' '); $('#'+row.value._id).click(function() { $('#idId').val(row.value._id);
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; }); }); } }); }
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
Iris Couch Cloud CouchDB hosting Free service
Iris Couch Demo…
References CouchDB - The Definitive Guide, J. Chris Anderson, Jan Lehnardt & Noah Slater Beginning CouchDB, Joe Lennon
Thank You...