Class: DeltaSharing::Schema

Inherits:
Object
  • Object
show all
Defined in:
lib/delta_sharing/schema.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(schema_string) ⇒ Schema

Returns a new instance of Schema.



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# File 'lib/delta_sharing/schema.rb', line 7

def initialize(schema_string)
  schema_json = JSON.parse(schema_string)
  @fields = schema_json['fields'] || []
  @arrow_schema = build_arrow_schema
end

Instance Attribute Details

#arrow_schema ⇒ Object (readonly)

Returns the value of attribute arrow_schema.



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# File 'lib/delta_sharing/schema.rb', line 5

def arrow_schema
  @arrow_schema
end

#fields ⇒ Object (readonly)

Returns the value of attribute fields.



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# File 'lib/delta_sharing/schema.rb', line 5

def fields
  @fields
end

Instance Method Details

#build_arrow_schema ⇒ Object 



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# File 'lib/delta_sharing/schema.rb', line 21

def build_arrow_schema
  fields = @fields.map do |field|
    arrow_type = delta_type_to_arrow_type(field['type'])
    Arrow::Field.new(field['name'], arrow_type, field['nullable'])
  end

  Arrow::Schema.new(fields)
end

#delta_type_to_arrow_type(delta_type) ⇒ Object 



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# File 'lib/delta_sharing/schema.rb', line 30

def delta_type_to_arrow_type(delta_type)
  case delta_type
  when 'boolean'
    Arrow::BooleanDataType.new
  when 'byte'
    Arrow::Int8DataType.new
  when 'short'
    Arrow::Int16DataType.new
  when 'integer'
    Arrow::Int32DataType.new
  when 'long'
    Arrow::Int64DataType.new
  when 'float'
    Arrow::FloatDataType.new
  when 'double'
    Arrow::DoubleDataType.new
  when 'string'
    Arrow::StringDataType.new
  when 'binary'
    Arrow::BinaryDataType.new
  when 'date'
    Arrow::Date32DataType.new
  when 'timestamp'
    Arrow::TimestampDataType.new(:micro)
  else
    if delta_type.is_a?(Hash)
      case delta_type['type']
      when 'decimal'
        Arrow::DecimalDataType.new(delta_type['precision'], delta_type['scale'])
      when 'array'
        element_type = delta_type_to_arrow_type(delta_type['elementType'])
        Arrow::ListDataType.new(element_type)
      when 'map'
        key_type = delta_type_to_arrow_type(delta_type['keyType'])
        value_type = delta_type_to_arrow_type(delta_type['valueType'])
        Arrow::MapDataType.new(key_type, value_type)
      when 'struct'
        fields = delta_type['fields'].map do |field|
          field_type = delta_type_to_arrow_type(field['type'])
          Arrow::Field.new(field['name'], field_type, field['nullable'])
        end
        Arrow::StructDataType.new(fields)
      else
        Arrow::StringDataType.new # Fallback to string
      end
    else
      Arrow::StringDataType.new # Fallback to string
    end
  end
end

#field_index(name) ⇒ Object 



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# File 'lib/delta_sharing/schema.rb', line 17

def field_index(name)
  @fields.find_index { |f| f['name'] == name }
end

#field_names ⇒ Object 



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# File 'lib/delta_sharing/schema.rb', line 13

def field_names
  @fields.map { |f| f['name'] }
end