Migration of MySql Tables to Cassandra table

In this section, we will let you know how to migrate MySql table to Cassandra table.
1. Create database in MySql.

create database mysql_to_cassandra ;

2. Create table in MySql.

CREATE TABLE `history` (  `id` varchar(30) DEFAULT NULL,  `city` varchar(30) DEFAULT NULL,  `province` varchar(30) DEFAULT NULL,  `country` varchar(30) DEFAULT NULL,  `zipCode` varchar(30) DEFAULT NULL,  `type` varchar(30) DEFAULT NULL,  `hasAirCondition` varchar(10) DEFAULT NULL,  `hasGarden` varchar(10) DEFAULT NULL,  `hasPool` varchar(10) DEFAULT NULL,  `isCloseToBeach` varchar(10) DEFAULT NULL,  `dailyPrice` float DEFAULT NULL,  `currency` varchar(10) DEFAULT NULL,  `roomsNumber` int(10) DEFAULT NULL,  `created_at` datetime DEFAULT NULL ) ; 

3. Insert one record in the table history;

insert into history( id ,  city ,  province ,  country ,  zipCode ,  type ,  hasAirCondition ,  hasGarden ,  hasPool ,  isCloseToBeach ,  dailyPrice  ,  currency ,  roomsNumber ,  created_at) values ("zZC8U",  "Mumbai", "province2", "india", "122001M", "studio", true, false, true, true, 14.92, "INR", 231, "2016-06-08 00:23:54" ); 

4. Take backup in csv in MySql console as given below.

select id, city, country, created_at, currency, dailyPrice, hasaircondition, hasgarden, isclosetobeach, province, type, zipcode from history INTO OUTFILE '/tmp/cql_cass.csv' FIELDS ENCLOSED BY '"' TERMINATED BY ',' ESCAPED BY '"' LINES TERMINATED BY '\r\n' ; 

5. Now you have backup of mysql table, and then we will create KEYSPACE(acronym of database) & table in Cassandra and import to this table.

6. Login to cqlsh console and create KeySpace as given below.

CREATE KEYSPACE from_mysql WITH replication = {'class': 'SimpleStrategy', 'replication_factor': '1'}  AND durable_writes = true; 

7. Create table in this keyspace/

use from_mysql ; 

;

CREATE TABLE mysql_table_data (id text PRIMARY KEY, city_name text, country text, created_at timestamp, currency text, dailyprice float, hasaircondition boolean, hasgarden boolean, haspool boolean, isclosetobeach boolean, province text, roomsnumber int, type text, zipcode text) ; 

8. Inserting data from the backup, we have created from MySql.

copy mysql_table_data (id, city, country, created_at, currency, dailyPrice, hasaircondition, hasgarden, isclosetobeach, province, type, zipcode ) from '/tmp/cql_cass.csv' ; 

9, You can verify the data using the command given below.

select * from mysql_table_data ; 

How To change data type in MongoDB

In this article, I will let you know how to change data type from String to Integer and vice versa.
String to Integer data type conversion
1. First check is there any data in string for which you want to convert the data to Integer 64, It’s NumberLong() data type in MongoDB.

db.collection_name.find({"field_name": {$exists: true, $type : 2}  } )

If count is more than 0 then it means data is in String for the specific field_name.
2. Conversion to Integer from String

db.collection_name.find({"field_name": {$exists: true, $type : 2}  }).forEach( function (x) { x.field_name = new NumberLong(x.field_name); db.collection_name.save(x); });

Above java script function will convert String type data to Integer 64.
3. If field has empty string then you can convert that docs to NumberLong(0) as per given below statement.

db.collection_name.find({"field_name": {$eq = "", $type : 2}  }).forEach( function (x) { x.field_name = new NumberLong(0); db.collection_name.save(x); });

Integer data type to String conversion
1. Check whether any docs are there or not from the given below query.

db.collection_name.find({"field_name": {$exists: true, $type : 18}  } )

If Count is more than 0 then follow the next steps.
2. Conversion of Integer data to String.

db.collection_name.find({"field_name": {$exists: true, $type : 18}  }).forEach( function (x) { x.field_name = "" + x.field_name; db.collection_name.save(x); });

Thanks for the going through the article