Class: DataDuck::Table

Inherits:
Object
  • Object
show all
Defined in:
lib/dataduck/table.rb

Class Attribute Summary collapse

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Class Attribute Details

.actions ⇒ Object

Returns the value of attribute actions.



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# File 'lib/dataduck/table.rb', line 8

def actions
  @actions
end

.output_schema ⇒ Object

Returns the value of attribute output_schema.



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# File 'lib/dataduck/table.rb', line 7

def output_schema
  @output_schema
end

.sources ⇒ Object

Returns the value of attribute sources.



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# File 'lib/dataduck/table.rb', line 6

def sources
  @sources
end

Instance Attribute Details

#data ⇒ Object

Returns the value of attribute data.



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# File 'lib/dataduck/table.rb', line 11

def data
  @data
end

#errors ⇒ Object

Returns the value of attribute errors.



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# File 'lib/dataduck/table.rb', line 12

def errors
  @errors
end

Class Method Details

.output(schema) ⇒ Object 



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# File 'lib/dataduck/table.rb', line 42

def self.output(schema)
  self.output_schema ||= {}
  self.output_schema.merge!(schema)
end

.source(source_name, source_table_or_query = nil, source_columns = nil) ⇒ Object 



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# File 'lib/dataduck/table.rb', line 26

def self.source(source_name, source_table_or_query = nil, source_columns = nil)
  self.sources ||= []

  source_spec = {}
  if source_table_or_query.respond_to?(:to_s) && source_table_or_query.to_s.downcase.include?('select ')
    source_spec = {query: source_table_or_query}
  elsif source_columns.nil? && source_table_or_query.respond_to?(:each)
    source_spec = {columns: source_table_or_query, table_name: DataDuck::Util.camelcase_to_underscore(self.name)}
  else
    source_spec = {columns: source_columns, table_name: source_table_or_query.to_s}
  end

  source_spec[:source] = DataDuck::Source.source(source_name)
  self.sources << source_spec
end

.transforms(transformation_name) ⇒ Object 



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# File 'lib/dataduck/table.rb', line 14

def self.transforms(transformation_name)
  self.actions ||= []
  self.actions << [:transform, transformation_name]
end

.validates(validation_name) ⇒ Object 



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# File 'lib/dataduck/table.rb', line 20

def self.validates(validation_name)
  self.actions ||= []
  self.actions << [:validate, validation_name]
end

Instance Method Details

#actions ⇒ Object 



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# File 'lib/dataduck/table.rb', line 47

def actions
  self.class.actions
end

#batch_size ⇒ Object 



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# File 'lib/dataduck/table.rb', line 149

def batch_size
  nil
end

#building_name ⇒ Object 



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# File 'lib/dataduck/table.rb', line 163

def building_name
  self.should_fully_reload? ? self.staging_name : self.name
end

#check_table_valid! ⇒ Object 



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# File 'lib/dataduck/table.rb', line 51

def check_table_valid!
  if !self.batch_size.nil?
    raise Exception.new("Table #{ self.name }'s batch_size must be > 0") unless self.batch_size > 0
    raise Exception.new("Table #{ self.name } has batch_size defined but no extract_by_column") if self.extract_by_column.nil?
  end
end

#distribution_key ⇒ Object 



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# File 'lib/dataduck/table.rb', line 58

def distribution_key
  if self.output_column_names.include?("id")
    "id"
  else
    nil
  end
end

#etl!(destinations) ⇒ Object 



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# File 'lib/dataduck/table.rb', line 66

def etl!(destinations)
  if destinations.length != 1
    raise ArgumentError.new("DataDuck can only etl to one destination at a time for now.")
  end
  self.check_table_valid!
  destination = destinations.first

  if self.should_fully_reload?
    destination.drop_staging_table!(self)
  end

  batch_number = 0
  while batch_number < 1_000
    batch_number += 1
    self.extract!(destination)
    self.transform!
    destination.load_table!(self)

    if self.batch_size.nil?
      break
    else
      if self.batch_size == self.data.length
        DataDuck::Logs.info "Finished batch #{ batch_number }, continuing with the next batch"
      else
        DataDuck::Logs.info "Finished batch #{ batch_number } (last batch)"
        break
      end
    end
  end

  self.data = []

  if self.should_fully_reload?
    destination.finish_fully_reloading_table!(self)
  end
end

#extract!(destination = nil) ⇒ Object 



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# File 'lib/dataduck/table.rb', line 103

def extract!(destination = nil)
  DataDuck::Logs.info "Extracting table #{ self.name }"

  self.errors ||= []
  self.data = []
  self.class.sources.each do |source_spec|
    source = source_spec[:source]
    my_query = self.extract_query(source_spec, destination)
    results = source.query(my_query)
    self.data = results
  end
  self.data
end

#extract_by_column ⇒ Object 



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# File 'lib/dataduck/table.rb', line 153

def extract_by_column
  return 'updated_at' if self.output_column_names.include?("updated_at")

  nil
end

#extract_query(source_spec, destination = nil) ⇒ Object 



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# File 'lib/dataduck/table.rb', line 117

def extract_query(source_spec, destination = nil)
  escape_char = source_spec[:source].escape_char

  base_query = source_spec.has_key?(:query) ? source_spec[:query] :
     "SELECT #{ escape_char }#{ source_spec[:columns].sort.join(escape_char + ',' + escape_char) }#{ escape_char } FROM #{ source_spec[:table_name] }"

  extract_by_clause = ""
  limit_clause = ""

  if self.extract_by_column
    if destination.table_names.include?(self.building_name)
      extract_by_value = destination.query("SELECT MAX(#{ self.extract_by_column }) AS val FROM #{ self.building_name }").first
      extract_by_value = extract_by_value.nil? ? nil : extract_by_value[:val]

      if extract_by_value
        extract_by_clause = "WHERE #{ self.extract_by_column } >= '#{ extract_by_value }'"
      end
    end

    limit_clause = self.batch_size ? "ORDER BY #{ self.extract_by_column } LIMIT #{ self.batch_size }" : ""
  end

  [base_query, extract_by_clause, limit_clause].join(' ').strip
end

#indexes ⇒ Object 



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# File 'lib/dataduck/table.rb', line 142

def indexes
  which_columns = []
  which_columns << "id" if self.output_column_names.include?("id")
  which_columns << "created_at" if self.output_column_names.include?("created_at")
  which_columns
end

#name ⇒ Object 



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# File 'lib/dataduck/table.rb', line 214

def name
  DataDuck::Util.camelcase_to_underscore(self.class.name)
end

#output_column_names ⇒ Object 



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# File 'lib/dataduck/table.rb', line 175

def output_column_names
  self.output_schema.keys.sort.map(&:to_s)
end

#output_schema ⇒ Object 



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# File 'lib/dataduck/table.rb', line 171

def output_schema
  self.class.output_schema || {}
end

#should_fully_reload? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/dataduck/table.rb', line 159

def should_fully_reload?
  false # Set to true if you want to fully reload a table with each ETL
end

#show ⇒ Object 



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# File 'lib/dataduck/table.rb', line 179

def show
  puts "Table #{ self.name }"
  self.class.sources.each do |source_spec|
    puts "\nSources from #{ source_spec[:table_name] || source_spec[:query] } on #{ source_spec[:source].name }"
    source_spec[:columns].each do |col_name|
      puts "  #{ col_name }"
    end
  end

  puts "\nOutputs "
  num_separators = self.output_schema.keys.map { |key| key.length }.max
  self.output_schema.each_pair do |name, datatype|
    puts "  #{ name }#{ ' ' * (num_separators + 2 - name.length) }#{ datatype }"
  end
end

#staging_name ⇒ Object 



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# File 'lib/dataduck/table.rb', line 167

def staging_name
  "zz_dataduck_#{ self.name }"
end

#transform! ⇒ Object 



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# File 'lib/dataduck/table.rb', line 195

def transform!
  DataDuck::Logs.info "Transforming table #{ self.name }"

  self.errors ||= []
  self.class.actions ||= []
  self.class.actions.each do |action|
    action_type = action[0]
    action_method_name = action[1]
    if action_type == :transform
      self.data.map! { |row| self.public_send(action_method_name, row) }
    elsif action_type == :validate
      self.data.each do |row|
        error = self.public_send(action_method_name, row)
        self.errors << error if !error.blank?
      end
    end
  end
end