Class: Innodb::Field

Inherits:
Object
  • Object
show all
Defined in:
lib/innodb/field.rb

Overview

A single field in an InnoDB record (within an INDEX page). This class provides essential information to parse records: the length of the fixed width portion of the field

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(position, type, *properties) ⇒ Field

Returns a new instance of Field.



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# File 'lib/innodb/field.rb', line 7

def initialize(position, type, *properties)
  @position = position
  @type, @fixed_len, @variable_len = parse_data_type(type.to_s)
  @nullable = (not properties.include?(:NOT_NULL))
  @unsigned = properties.include?(:UNSIGNED)
end

Instance Attribute Details

#fixed_len ⇒ Object (readonly)

Returns the value of attribute fixed_len.



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# File 'lib/innodb/field.rb', line 5

def fixed_len
  @fixed_len
end

#nullable ⇒ Object (readonly)

Returns the value of attribute nullable.



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# File 'lib/innodb/field.rb', line 5

def nullable
  @nullable
end

#position ⇒ Object (readonly)

Returns the value of attribute position.



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# File 'lib/innodb/field.rb', line 5

def position
  @position
end

#variable_len ⇒ Object (readonly)

Returns the value of attribute variable_len.



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# File 'lib/innodb/field.rb', line 5

def variable_len
  @variable_len
end

Instance Method Details

#fixed_len_map ⇒ Object

Maps data type to fixed storage length.



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# File 'lib/innodb/field.rb', line 31

def fixed_len_map
  {
    :TINYINT    => 1,
    :SMALLINT   => 2,
    :MEDIUMINT  => 3,
    :INT        => 4,
    :BIGINT     => 8,
  }
end

#get_variable_len(record) ⇒ Object

Return the length of this variable-length field.



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# File 'lib/innodb/field.rb', line 51

def get_variable_len(record)
  case record[:format]
  when :compact
    header = record[:header]
    header[:variable_length][@position]
  end
end

#null?(record) ⇒ Boolean

Return whether this field is NULL.

Returns:

  • (Boolean) 


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# File 'lib/innodb/field.rb', line 42

def null?(record)
  case record[:format]
  when :compact
    header = record[:header]
    header[:null_bitmap][@position]
  end
end

#parse_data_type(data_type) ⇒ Object

Parse the data type description string of a field.



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# File 'lib/innodb/field.rb', line 15

def parse_data_type(data_type)
  case data_type
  when /^(tinyint|smallint|mediumint|int|bigint)$/i
    type = data_type.upcase.to_sym
    fixed_len = fixed_len_map[type]
    [type, fixed_len, 0]
  when /^varchar\((\d+)\)$/i
    [:VARCHAR, 0, $1.to_i]
  when /^char\((\d+)\)$/i
    [:CHAR, $1.to_i, 0]
  else
    raise "Data type '#{data_type}' is not supported"
  end
end

#read(record, cursor) ⇒ Object

Read an InnoDB encoded data field.



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# File 'lib/innodb/field.rb', line 60

def read(record, cursor)
  return :NULL if @nullable and null?(record)

  case @type
  when :TINYINT, :SMALLINT, :MEDIUMINT, :INT, :BIGINT
    symbol = @unsigned ? :get_uint_by_size : :get_i_sint_by_size
    cursor.send(symbol, @fixed_len)
  when :VARCHAR
    cursor.get_bytes(get_variable_len(record))
  when :CHAR
    # Fixed-width character fields will be space-padded up to their length,
    # so SQL defines that trailing spaces should be removed.
    cursor.get_bytes(fixed_len).sub(/[ ]+$/, "")
  end
end