WhichDB database tutorials

cassandra/advanced/collection-data-types.md

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+CQL also provides collection data types. Following list provides different data types available in cassandra.
+
+1. List - Collection of one or more ordered elements.
+1. map - Collection of key-value pairs.
+1. set - Collection of one or more elments.
+
+### List
+List is used to maintain the order of elements allowing duplicates.
+
+* Creating a Table with List
+```sh
+CREATE TABLE employee(id int PRIMARY KEY, name text, email list<text>);
+```
+
+* Inserting Data into List
+```sh
+INSERT INTO employee(id, name, email) VALUES (1, 'john',
+['[email protected]','[email protected]'])
+```
+* Updating a List
+```sh
+UPDATE employee SET email = email +['[email protected]']
+WHERE name = 'john';
+```
+
+### SET
+SET is used to store group of data and the elements will be returned in sorted order.
+
+* Creating a Table with Set
+```sh
+CREATE TABLE employee2(id int PRIMARY KEY, name text, mobile set<varint>);
+```
+
+* Inserting Data into Set
+```sh
+INSERT INTO employee2(id, name, mobile) VALUES (1, 'kevin',
+{9999911122, 9998855664})
+```
+* Updating a List
+```sh
+UPDATE employee2 SET mobile = mobile +{9898989898}
+WHERE name = 'kevin';
+```
+
+
+### MAP
+Map is used to store key-value pair of elements.
+
+* Creating a Table with Map
+```sh
+CREATE TABLE employee3(id int PRIMARY KEY, name text, address map<text, text>);
+```
+
+* Inserting Data into Map
+```sh
+INSERT INTO employee3(id, name, address) VALUES (1, 'smith',
+{'home':'san jose','work':'chicago'})
+```
+* Updating a Map
+```sh
+UPDATE employee3 SET address = address +{'permanent':'New york'}
+WHERE name = 'smith';
+```

cassandra/crud-operations/creating-data.md

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+INSERT command is used to insert data into columns of the table.
+
+Syntax
+
+```sh
+INSERT INTO <tablename>  
+(<column1 name>, <column2 name>....)  
+VALUES (<value1>, <value2>....)  
+USING <option>   
+```
+
+
+Example : 
+```sh
+INSERT INTO student (id, name, city)   
+VALUES(1, 'Paul', 'Texas');  
+INSERT INTO student (id, name, city)   
+VALUES(2, 'John', 'New York');
+INSERT INTO student (id, name, city)   
+VALUES(1, 'Max', 'New Jersey');
+```   

cassandra/crud-operations/creating-keyspace.md

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+A keyspace is RDBMS database which contains tables, columns and data.
+
+### Syntax
+```sh
+CREATE KEYSPACE <identifier> WITH <properties>   
+```
+
+```sh
+Create keyspace KeyspaceName with replicaton={'class':strategy name,   
+'replication_factor': No of replications on different nodes}   
+```
+
+### Strategy, Replication Factor
+
+There are two types of strategy declarations.
+
+* Simple Strategy - It is used in case of single data center. This is not a wise choice for production, it may lead to latency.
+* NetworkTopologyStrategy - It is used in case of more data centers. Replication factor is provided for each data center separately.
+
+Replication Factor- Replication factor is the number of replicas of data placed on different nodes. Atleast 3 replication factor is required to attain no single point of failure.
+
+Example
+
+```sh
+CREATE KEYSPACE whichdb  
+WITH replication = {'class':'SimpleStrategy', 'replication_factor' : 3};  
+ ```
+
+
+ DESCRIBE Keyword is used to display all the keyspaces created.
+```sh
+DESCRIBE keyspaces
+
+system_schema system system_traces
+system_auth system_distributed whichdb
+ ```
+
+USE keyword is used to use the keyspace
+```sh
+USE whichdb
+```

cassandra/crud-operations/creating-table.md

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+CREATE command is used to create a table. Here column family is used to store data just like tables in RDBMS.
+
+Syntax
+
+```sh
+CREATE (TABLE | COLUMNFAMILY) <tablename>  
+('<column-definition>' , '<column-definition>')  
+(WITH <option> AND <option>)   
+```
+
+or
+
+```sh
+CREATE TABLE tablename(  
+   column1 name datatype PRIMARYKEY,  
+   column2 name data type,  
+   column3 name data type.  
+   )  
+
+```
+
+Example : 
+```sh
+CREATE TABLE student(  
+   id int PRIMARY KEY,  
+   name text,  
+   city text,     
+   mobile varint  
+);
+```   

cassandra/crud-operations/deleting-data.md

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+DELETE command is used to delete data from cassandra table, You can delete complete table or particular data based on condition
+
+```sh
+DELETE FROM <identifier> WHERE <condition>;   
+```
+
+### Deleting an Entire Table
+```sh
+DELETE FROM student;   
+```
+
+### Deleting an Particular Data based on condition
+WHERE clause is specified.
+```sh
+DELETE FROM student where id = 3;   
+```
+
+### Deleting an specific column name
+```sh
+DELETE city FROM student WHERE id=4;   
+```
+

cassandra/crud-operations/deleting-keyspace.md

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+Drop command is used to drop keyspaces with all the data, columns and indexes from cassandra
+
+```sh
+DROP keyspace whichdb
+```

cassandra/crud-operations/reading-data.md

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+## Reading whole table from a keyspace
+SELECT is used to read data from cassandra table.
+
+```sh
+SELECT FROM <tablename>   
+
+SELECT * FROM student;  
+```
+
+## Reading Particular columns in a table
+Required columns are specified instead of *.
+```sh
+SELECT id, name, city FROM student;   
+```
+
+## Reading data from table based on condition
+WHERE clause is used to return a data based on given condition
+
+```sh
+SELECT * FROM student WHERE id=2;    
+```
+
+

cassandra/crud-operations/updating-data.md

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+UPDATE command is used to update the data in table. Where clause can used to update rows based on condition.
+
+
+Syntax
+```sh
+UPDATE <TABLE>  
+SET <COLUMN> = <VALUE>  
+<COLUMN> = <value>....  
+WHERE <condition>   
+```
+
+## Update multiple values
+```sh
+UPDATE <TABLE>  
+SET <COLUMN1> = <VALUE1>,  
+SET <COLUMN2> = <VALUE2>  
+<COLUMN> = <value>....  
+WHERE <condition>   
+```
+
+
+### Example
+
+```sh
+UPDATE student SET city='New York',name='Rahul'  
+WHERE id=2;   
+```

cassandra/index.json

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+[
+    {
+        "title": "Introduction",
+        "path": "introduction",
+        "links": [
+            {
+                "title": "What is Cassandra",
+                "path": "what-is-cassandra"
+            },
+            {
+                "title": "Key Concepts",
+                "path": "key-concepts"
+            },
+            {
+                "title": "Installation",
+                "path": "installation"
+            }
+        ]
+    },
+    {
+        "title": "CRUD Operations",
+        "path": "crud-operations",
+        "links": [
+            {
+                "title": "Creating Keyspace",
+                "path": "creating-keyspace"
+            },
+            {
+                "title": "Deleting Keyspace",
+                "path": "deleting-keyspace"
+            },
+            {
+                "title": "Creating Table",
+                "path": "creating-table"
+            },
+            {
+                "title": "Inserting Data",
+                "path": "creating-data"
+            },
+            {
+                "title": "Updating Data",
+                "path": "updating-data"
+            },
+            {
+                "title": "Deleting Data",
+                "path": "deleting-data"
+            }
+        ]
+    },
+    {
+        "title": "Advanced Topics",
+        "path": "advanced",
+        "links": [
+            {
+                "title": "Collection Data types",
+                "path": "collection-data-types"
+            }
+        ]
+    }
+]

cassandra/introduction/installation.md

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+## Installing on MacOS
+
+Easiest way to get Cassandra installed on MacOS is via Homebrew. You can run the following command to install Cassandra in MacOS
+```sh
+brew install cassandra
+```
+
+## Installing on Windows
+
+We can download the latest version of cassandra from the following website
+http://cassandra.apache.org/download/
+
+Run the installation and open cassandra
+
+### Installing Fron Debian Packages
+```sh
+echo "deb http://www.apache.org/dist/cassandra/debian 311x main" | sudo tee -a /etc/apt/sources.list.d/cassandra.sources.list
+sudo apt-get update
+sudo apt-get install cassandra
+```
+
+### Installing Fron RPM Packages
+```sh
+[cassandra]
+name=Apache Cassandra
+baseurl=https://www.apache.org/dist/cassandra/redhat/311x/
+gpgcheck=1
+repo_gpgcheck=1
+gpgkey=https://www.apache.org/dist/cassandra/KEYS
+
+sudo yum install cassandra
+```

cassandra/introduction/key-concepts.md

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+## Cassandra Query Language
+Cassandra Query Language (CQL) is used to access Cassandra database through queries. CQL Treats Database as keyspaces as a container of tables.
+
+## Terms Related to Cassandra
+* Node  - Node is place where data is stored.
+* Data Center - Data center is a collection of related nodes.
+* Cluster - Cluster is component containing one or more data centers.
+* Commit log - This is a crash recovery mechanism, every write operation is written into the log.
+
+## Data Replication in Cassandra
+In cassandra nodes in a cluster acts as replicas for a given piece of data. If a node responds with out-of-date value, Cassandra will return the recent value and performs a repair in the background to repair the old value.
+
+## Keyspace, Table, Data
+Cassandra provides keyspaces(Database) which contains multiple tables. Tables contain data
+
+## Cassandra CQLsh
+Cassandra CQL shell is utility to interact with Cassandra using CQL Queries. 

cassandra/introduction/what-is-cassandra.md

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+Cassandra is a free and open-source, distributed NoSQL database management system. It is provided by Apache. It is designed to handle huge amount of data providing high performance, high scalability across servers without any failure.

couchdb/crud-operations/creating-data.md

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+CouchDB curl utility provides PUT method to insert data/document into couchdb database.
+
+Syntax : 
+```sh
+curl -X PUT http://127.0.0.1:5984/<database>/"id" -d ' { document } '   
+```
+Example :
+```sh
+curl -X PUT \
+  http://127.0.0.1:5984/employee/1 \
+  -H 'Content-Type: application/json' \
+  -d '{
+    "name": "John",
+    "city": "New york",
+    "mobile": 9921829381
+}'
+
+{
+    "ok": true,
+    "id": "1",
+    "rev": "1-fef96a337fdc6197293y41fs64a4d2ea"
+}
+```
+Document id, datbase name needs to be specified in curl request.
+
+Document can be displayed in the following manner.
+
+```sh
+curl -X GET http://127.0.0.1:5984/employee/1
+
+{
+    "_id": "1",
+    "rev": "1-fef96a337fdc6197293y41fs64a4d2ea",
+    "name": "John",
+    "city": "New york",
+    "mobile": 9921829381
+}
+```
+