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As RisingWave is wire-compatible with PostgreSQL, you can use third-party PostgreSQL drivers to interact with RisingWave from your Ruby applications. In this guide, we use the ruby-pg driver to connect to RisingWave.

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Run RisingWave

To learn about how to run RisingWave, see Run RisingWave.

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Install the ruby-pg driver

For information about how to install ruby-pg, see the official ruby-pg documentation.

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Connect to RisingWave

To connect to RisingWave via ruby-pg: 
require 'pg'

conn = PG.connect(host: '127.0.0.1', port: 4566, dbname: 'dev', user: 'root')
The BasicTypeMapForResults class isn’t supported currently, you need to cast RisingWave types into Ruby types manually.

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Create a source

The code below creates a source walk with the datagen connector. The datagen connector is used to generate mock data. The walk source consists of two columns, distance and duration, which respectively represent the distance and the duration of a walk. The source is a simplified version of the data that is tracked by smart watches. 
require 'pg'

conn = PG.connect(host: '127.0.0.1', port: 4566, dbname: 'dev', user: 'root')

sql = <<-EOF
CREATE TABLE walk(distance INT, duration INT)
WITH (
    connector = 'datagen',
    fields.distance.kind = 'sequence',
    fields.distance.start = '1',
    fields.distance.end  = '60',
    fields.duration.kind = 'sequence',
    fields.duration.start = '1',
    fields.duration.end = '30',
    datagen.rows.per.second='15',
    datagen.split.num = '1'
) FORMAT PLAIN ENCODE JSON
EOF
conn.exec(sql) # Execute the query.
All the code examples in this guide include a section for connecting to RisingWave. If you perform multiple actions within one connection session, you do not need to repeat this section.

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Create a materialized view

The code in this section creates a materialized view counter to capture the latest total distance and duration. 
require 'pg'

conn = PG.connect(host: '127.0.0.1', port: 4566, dbname: 'dev', user: 'root')

sql = <<-EOF
CREATE MATERIALIZED VIEW counter
    AS SELECT
    SUM(distance) as total_distance,
    SUM(duration) as total_duration
    FROM walk;
EOF
conn.exec(sql)

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Query a materialized view

The code in this section queries the materialized view counter to get real-time data. 
require 'pg'

conn = PG.connect(host: '127.0.0.1', port: 4566, dbname: 'dev', user: 'root')

res = conn.exec('SELECT * FROM counter;')
res.each do |row|
  puts row
end