Module: RedshiftETL::Load

Defined in:
lib/redshift_etl/load.rb

Overview

TODO: break into some objects

Class Method Summary collapse

Class Method Details

.call(config) ⇒ Object 



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# File 'lib/redshift_etl/load.rb', line 7

def self.call(config)
  load_into_redshift(config)
end

.create_table(config) ⇒ Object 



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# File 'lib/redshift_etl/load.rb', line 58

def self.create_table(config)
  create_table_statement(config, staging_table_name(config))
end

.create_table_statement(config, table_name) ⇒ Object 



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# File 'lib/redshift_etl/load.rb', line 62

def self.create_table_statement(config, table_name)
  sql = "create table if not exists #{table_name} ("
  sql << config.columns.map { |column, type| "#{column} #{type}" }.join(', ')
  sql << "); "
end

.load_into_redshift(config) ⇒ Object 



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# File 'lib/redshift_etl/load.rb', line 11

def self.load_into_redshift(config)
  sql_statements = []
  sql_statements << "create schema if not exists #{config.redshift_schema};"
  sql_statements << "set search_path=#{config.redshift_schema};"
  sql_statements << "drop table if exists #{config.redshift_table}_staging;"
  sql_statements << create_table(config)

  sql_statements << "
  copy #{staging_table_name(config)} from 's3://#{config.s3_bucket_name}/#{config.temp_s3_path}'
  credentials 'aws_access_key_id=#{config.s3_access_key_id};aws_secret_access_key=#{config.s3_secret_access_key}'
  csv
  gzip
  ignoreheader 1
  trimblanks
  statupdate on
  truncatecolumns
  timeformat 'auto'; "

  if config.incremental_updates?
    sql_statements << "
      begin;

        #{create_table_statement(config, config.redshift_table)}

        delete from #{config.redshift_table}
        using #{staging_table_name(config)}
        where #{config.redshift_table}.#{config.primary_key} = #{staging_table_name(config)}.#{config.primary_key};

        insert into #{config.redshift_table}
        select * from #{staging_table_name(config)};

        drop table #{staging_table_name(config)};

      commit;
      "
  else
    sql_statements << "drop table if exists #{ config.redshift_table};"
    sql_statements << "alter table #{staging_table_name(config)} rename to #{config.redshift_table};"
  end

  Sequel.connect(config.redshift_connection + "?force_standard_strings=f&client_min_messages=") do |db|
    sql_statements.each do |statement|
      print db[statement].get
    end
  end
end

.staging_table_name(config) ⇒ Object 



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# File 'lib/redshift_etl/load.rb', line 68

def self.staging_table_name(config)
  config.redshift_table + "_staging"
end