Class: MysqlReplicator::Binlogs::TableMapEventParser

Inherits:
Object
  • Object
show all
Defined in:
lib/mysql_replicator/binlogs/table_map_event_parser.rb

Class Method Summary collapse

Class Method Details

.extract_enum_from_column_type(data_type, column_type) ⇒ Object 



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# File 'lib/mysql_replicator/binlogs/table_map_event_parser.rb', line 140

def self.extract_enum_from_column_type(data_type, column_type)
  return nil unless data_type.downcase == 'enum'

  # Extract values from ENUM('value1','value2','value3')
  if column_type =~ /enum\((.*)\)/i
    enum_string = ::Regexp.last_match(1) || ''
    # Extract value by arround single quote
    values = enum_string.scan(/'([^']*)'/).flatten
    return values
  end

  nil
end

.get_table_columns(connection, database, table) ⇒ Object 



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# File 'lib/mysql_replicator/binlogs/table_map_event_parser.rb', line 84

def self.get_table_columns(connection, database, table)
  # Create a separate connection to query table structure
  query_connection = connection.dup

  # Query table structure
  # IMPORTANT: Column data is stored in ascending order of ORDINAL_POSITION
  query = <<~SQL
    SELECT
      ORDINAL_POSITION,
      DATA_TYPE,
      COLUMN_NAME,
      COLUMN_TYPE,
      IS_NULLABLE,
      COLUMN_DEFAULT,
      NUMERIC_PRECISION,
      NUMERIC_SCALE,
      CHARACTER_MAXIMUM_LENGTH,
      CHARACTER_SET_NAME,
      COLLATION_NAME,
      COLUMN_KEY
    FROM INFORMATION_SCHEMA.COLUMNS
    WHERE TABLE_SCHEMA = '#{database}'
      AND TABLE_NAME = '#{table}'
    ORDER BY ORDINAL_POSITION
  SQL
  result = query_connection.query(query)

  # Close the separated connection
  query_connection.close

  if result.nil? || !result[:rows].is_a?(Array)
    return []
  end

  result[:rows].map do |row|
    {
      ordinal_position: row[:ordinal_position].to_i,
      data_type: row[:data_type].to_s,
      column_name: row[:column_name].to_s,
      column_type: row[:column_type].to_s,
      enum_values: extract_enum_from_column_type(row[:data_type].to_s, row[:column_type].to_s),
      nullable: row[:is_nullable] == 'YES',
      column_default: row[:column_default],
      numeric_precision: row[:numeric_precision].to_i,
      numeric_scale: row[:numeric_scale].to_i,
      character_maximum_length: row[:character_maximum_length].to_i,
      character_set_name: row[:character_set_name].to_s,
      collation_name: row[:collation_name].to_s,
      primary_key: row[:column_key] == 'PRI'
    }
  end
end

.parse(payload, connection) ⇒ Object 



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# File 'lib/mysql_replicator/binlogs/table_map_event_parser.rb', line 36

def self.parse(payload, connection)
  offset = 0

  # Table ID (6 bytes)
  table_id = to_little_endian(MysqlReplicator::StringUtil.read_array_from_int8(payload[0, 6]))
  offset += 6

  # Flags (2 bytes)
  flags = MysqlReplicator::StringUtil.read_uint16(payload[offset, 2])
  offset += 2

  # Database name length (1 byte) + database name + null terminator
  db_name_len = MysqlReplicator::StringUtil.read_uint8(payload[offset, 1])
  offset += 1
  database_name = MysqlReplicator::StringUtil.read_str(payload[offset, db_name_len])
  offset += db_name_len + 1 # +1 for null terminator

  # Table name length (1 byte) + table name + null terminator
  table_name_len = MysqlReplicator::StringUtil.read_uint8(payload[offset, 1])
  offset += 1
  table_name = MysqlReplicator::StringUtil.read_str(payload[offset, table_name_len])

  # Get actual column names from table schema
  columns = get_table_columns(connection, database_name, table_name)

  {
    database: database_name,
    table: table_name,
    table_id: table_id,
    columns: columns,
    flags: flags
  }
end

.to_little_endian(bytes) ⇒ Object 



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# File 'lib/mysql_replicator/binlogs/table_map_event_parser.rb', line 72

def self.to_little_endian(bytes)
  result = 0
  bytes.each_with_index do |byte, i|
    result |= (byte << (i * 8))
  end
  result
end