module Sequel::Database::SplitAlterTable

Private Instance Methods

apply_alter_table(name, ops) click to toggle source

Preprocess the array of operations. If it looks like some operations depend on results of earlier operations and may require reloading the schema to work correctly, split those operations into separate lists, and between each list, remove the cached schema so that the later operations deal with the then current table schema.

# File lib/sequel/adapters/utils/split_alter_table.rb, line 9
def apply_alter_table(name, ops)
  modified_columns = []
  op_groups = [[]]
  ops.each do |op|
    case op[:op]
    when :add_column, :set_column_type, :set_column_null, :set_column_default
      if modified_columns.include?(op[:name])
        op_groups << []
      else
        modified_columns << op[:name]
      end
    when :rename_column
      if modified_columns.include?(op[:name]) || modified_columns.include?(op[:new_name])
        op_groups << []
      end
      modified_columns << op[:name] unless modified_columns.include?(op[:name])
      modified_columns << op[:new_name] unless modified_columns.include?(op[:new_name])
    end
    op_groups.last << op
  end

  op_groups.each do |opgs|
    next if opgs.empty?
    alter_table_sql_list(name, opgs).each{|sql| execute_ddl(sql)}
    remove_cached_schema(name)
  end
end