Class: DbCopier::Worker

Inherits:
Object
  • Object
show all
Defined in:
lib/db-copier/worker.rb

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ Worker

Returns a new instance of Worker.

Raises:

  • (ArgumentError) 


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# File 'lib/db-copier/worker.rb', line 3

def initialize(options = {})
  @src_db_conn, @target_db_conn, @table_name, @rows_per_copy, @copy_columns = options[:src_db_conn], options[:target_db_conn],
          options[:table_name], (options[:rows_per_copy] || 1000), (options[:copy_columns] || [])
  raise ArgumentError unless @src_db_conn && @target_db_conn && @table_name
  @copy_columns ||= []
end

Instance Method Details

#copy_table ⇒ Object 



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# File 'lib/db-copier/worker.rb', line 10

def copy_table
  start = Time.now
  $stdout.print green, bold, "Thread: #{Thread.current.object_id} is copying table: #{@table_name}", reset, "\n"
  tab_to_copy = @table_name.to_sym
  num_rows = @src_db_conn[tab_to_copy].count
  i = 0
  #Create the table if it does not already exist
  unless @target_db_conn.table_exists?(tab_to_copy)
    table_creation_ddl = DbCopier.generate_create_table_ddl(@src_db_conn, tab_to_copy, tab_to_copy, @copy_columns)
    table_creation_ddl = ("@target_db_conn" + table_creation_ddl)
    eval table_creation_ddl
  end

  #This is the intersection of columns specified via the +copy_columns+ argumnent in the +for_table+ method
  #and those that actually exist in the target table.
  columns_in_target_db = @target_db_conn.schema(tab_to_copy).map {|cols| cols.first}
  columns_to_copy =
          if @copy_columns.count > 0
            @copy_columns & columns_in_target_db
          else
            columns_in_target_db
          end

  while i < num_rows
    rows_to_copy = @src_db_conn[tab_to_copy].select(*columns_to_copy).limit(@rows_per_copy, i).all
    #Special handling of datetime columns
    rows_to_copy.each { |col_name, col_val| rows_to_copy[col_name] = DateTime.parse(col_val) if col_val.class == Time }
    i += rows_to_copy.count
    @target_db_conn[tab_to_copy].multi_insert(rows_to_copy)
  end

  #copy indexes now
  @src_db_conn.indexes(tab_to_copy).each do |index_name, index_info|
    #Make sure we are adding an index to a column that is going to be there
    next unless (columns_to_copy & index_info[:columns] == index_info[:columns])
    @target_db_conn.add_index(tab_to_copy, index_info[:columns])
  end
  $stdout.print green,bold, "Thread: #{Thread.current.object_id} has COMPLETED copying table: #{@table_name} in #{Time.now - start} seconds", reset, "\n"
end