Class: DataSampler::Sample

Inherits:
Object
  • Object
show all
Defined in:
lib/data_sampler/sample.rb

Instance Method Summary collapse

Constructor Details

#initialize(connection, rows_per_table = 1000) ⇒ Sample

Returns a new instance of Sample.



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# File 'lib/data_sampler/sample.rb', line 7

def initialize(connection, rows_per_table = 1000)
  @connection = connection
  @rows_per_table = rows_per_table
  @table_samples = {}
  @computed = false
end

Instance Method Details

#compute! ⇒ Object 



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# File 'lib/data_sampler/sample.rb', line 14

def compute!
  @connection.tables.each do |table_name|
    # Workaround for inconsistent casing in table definitions (http://bugs.mysql.com/bug.php?id=60773)
    # table_name.downcase!
    @table_samples[table_name] = TableSample.new(@connection, table_name, @rows_per_table)
  end
  warn "Sampling #{@table_samples.count} tables from database `#{@connection.current_database}`..."
  @table_samples.values.map &:sample!
  warn "Ensuring referential integrity..."
  begin
    new_dependencies = 0
    @table_samples.values.each do |table_sample|
      newly_added = table_sample.ensure_referential_integrity(@table_samples)
      if newly_added > 0
        new_dependencies += newly_added
        warn "  Found #{newly_added} new dependents for table `#{table_sample.table_name}`"
      end
    end
    warn " Discovered #{new_dependencies} new dependencies" if new_dependencies > 0
  end while new_dependencies > 0
  warn "Referential integrity obtained"

  warn "Final sample contains:"
  @table_samples.values.each do |table_sample|
    warn "  #{table_sample.size} row(s) from `#{table_sample.table_name}`"
  end
  @computed = true
end

#to_sql ⇒ Object 



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# File 'lib/data_sampler/sample.rb', line 43

def to_sql
  compute! unless @computed
  @table_samples.values.collect(&:to_sql) * "\n"
end