Class: RBHive::SchemaDefinition

Inherits:
Object
  • Object
show all
Defined in:
lib/rbhive/schema_definition.rb

Constant Summary collapse

TYPES = 
{ 
  :boolean  => :to_s,
  :string   => :to_s,
  :bigint   => :to_i,
  :float    => :to_f,
  :double   => :to_f,
  :int      => :to_i,
  :smallint => :to_i,
  :tinyint  => :to_i,
}

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(schema, example_row) ⇒ SchemaDefinition

Returns a new instance of SchemaDefinition.



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# File 'lib/rbhive/schema_definition.rb', line 16

def initialize(schema, example_row)
  @schema = schema
  @example_row = example_row ? example_row.split("\t") : []
end

Instance Attribute Details

#schema ⇒ Object (readonly)

Returns the value of attribute schema.



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# File 'lib/rbhive/schema_definition.rb', line 3

def schema
  @schema
end

Instance Method Details

#coerce_column(column_name, value) ⇒ Object 



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# File 'lib/rbhive/schema_definition.rb', line 50

def coerce_column(column_name, value)
  type = column_type_map[column_name]
  conversion_method = TYPES[type]
  conversion_method ? value.send(conversion_method) : value
end

#coerce_row(row) ⇒ Object 



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# File 'lib/rbhive/schema_definition.rb', line 43

def coerce_row(row)
  column_names.zip(row.split("\t")).inject({}) do |hsh, (column_name, value)|
    hsh[column_name] = coerce_column(column_name, value)
    hsh
  end
end

#coerce_row_to_array(row) ⇒ Object 



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# File 'lib/rbhive/schema_definition.rb', line 56

def coerce_row_to_array(row)
  column_names.map { |n| row[n] }
end

#column_names ⇒ Object 



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# File 'lib/rbhive/schema_definition.rb', line 21

def column_names
  @column_names ||= begin
    schema_names = @schema.fieldSchemas.map {|c| c.name.to_sym }
    # Lets fix the fact that Hive doesn't return schema data for partitions on SELECT * queries
    # For now we will call them :_p1, :_p2, etc. to avoid collisions.
    offset = 0
    while schema_names.length < @example_row.length
      schema_names.push(:"_p#{offset+=1}")
    end
    schema_names
  end
end

#column_type_map ⇒ Object 



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# File 'lib/rbhive/schema_definition.rb', line 34

def column_type_map
  @column_type_map ||= column_names.inject({}) do |hsh, c| 
    definition = @schema.fieldSchemas.find {|s| s.name.to_sym == c }
    # If the column isn't in the schema (eg partitions in SELECT * queries) assume they are strings
    hsh[c] = definition ? definition.type.to_sym : :string
    hsh
  end
end