Apache Presto - MySQL Connector


Advertisements


The MySQL connector is used to query an external MySQL database.

Prerequisites

MySQL server installation.

Configuration Settings

Hopefully you have installed mysql server on your machine. To enable mysql properties on Presto server, you must create a file “mysql.properties” in “etc/catalog” directory. Issue the following command to create a mysql.properties file.

$ cd etc 
$ cd catalog 
$ vi mysql.properties   

connector.name = mysql 
connection-url = jdbc:mysql://localhost:3306 
connection-user = root 
connection-password = pwd 

Save the file and quit the terminal. In the above file, you must enter your mysql password in connection-password field.

Create Database in MySQL Server

Open MySQL server and create a database using the following command.

create database tutorials

Now you have created “tutorials” database in the server. To enable database type, use the command “use tutorials” in the query window.

Create Table

Let’s create a simple table on “tutorials” database.

create table author(auth_id int not null, auth_name varchar(50),topic varchar(100))

Insert Table

After creating a table, insert three records using the following query.

insert into author values(1,'Doug Cutting','Hadoop') 
insert into author values(2,’James Gosling','java') 
insert into author values(3,'Dennis Ritchie’,'C')

Select Records

To retrieve all the records, type the following query.

Query

select * from author

Result

auth_id    auth_name      topic  
1        Doug Cutting     Hadoop 
2        James Gosling    java 
3        Dennis Ritchie     C 

As of now, you have queried data using MySQL server. Let’s connect Mysql storage plugin to Presto server.

Connect Presto CLI

Type the following command to connect MySql plugin on Presto CLI.

./presto --server localhost:8080 --catalog mysql --schema tutorials 

You will receive the following response.

presto:tutorials> 

Here “tutorials” refers to schema in mysql server.

List Schemas

To list out all the schemas in mysql, type the following query in Presto server.

Query

presto:tutorials> show schemas from mysql;

Result

      Schema 
-------------------- 
 information_schema 
 performance_schema 
 sys 
 tutorials

From this result, we can conclude the first three schemas as predefined and the last one as created by yourself.

List Tables from Schema

Following query lists out all the tables in tutorials schema.

Query

presto:tutorials> show tables from mysql.tutorials; 

Result

  Table 
-------- 
 author

We have created only one table in this schema. If you have created multiple tables, it will list out all the tables.

Describe Table

To describe the table fields, type the following query.

Query

presto:tutorials> describe mysql.tutorials.author;

Result

  Column   |     Type     | Comment 
-----------+--------------+--------- 
 auth_id   | integer      | 
 auth_name | varchar(50)  | 
 topic     | varchar(100) |

Show Columns from Table

Query

presto:tutorials> show columns from mysql.tutorials.author; 

Result

 Column    |     Type     | Comment 
-----------+--------------+--------- 
 auth_id   | integer      | 
 auth_name | varchar(50)  | 
 topic     | varchar(100) |

Access Table Records

To fetch all the records from mysql table, issue the following query.

Query

presto:tutorials> select * from mysql.tutorials.author; 

Result

auth_id  |   auth_name    | topic 
---------+----------------+-------- 
       1 | Doug Cutting   | Hadoop 
       2 | James Gosling  | java 
       3 | Dennis Ritchie | C

From this result, you can retrieve mysql server records in Presto.

Create Table Using as Command

Mysql connector doesn’t support create table query but you can create a table using as command.

Query

presto:tutorials> create table mysql.tutorials.sample as 
select * from mysql.tutorials.author; 

Result

CREATE TABLE: 3 rows

You can’t insert rows directly because this connector has some limitations. It cannot support the following queries −

  • create
  • insert
  • update
  • delete
  • drop

To view the records in the newly created table, type the following query.

Query

presto:tutorials> select * from mysql.tutorials.sample; 

Result

auth_id  |   auth_name    | topic 
---------+----------------+-------- 
       1 | Doug Cutting   | Hadoop 
       2 | James Gosling  | java 
       3 | Dennis Ritchie | C


Advertisements