Mapping to Apache Parquet

Overview

Apache Parquet is an open source, column-oriented data file format designed for efficient data storage and retrieval. It provides high performance compression and encoding schemes to handle complex data in bulk and is supported in many programming languages and analytics tools.

This document describes how Aspect Models are converted into Apache Parquet files, including the mapping of SAMM data types to Parquet types and the flattening strategy for nested structures.

Rules for the construction of Apache Parquet files matching an Aspect Model

In order to create Apache Parquet files that correspond to an Aspect Model, the following rules are applied:

Flattening Strategy

An Aspect Model is serialized into a flattened columnar structure where nested Properties are represented using a double underscore (__) separator.
Property names in the Aspect Model should use single underscores (_) to avoid ambiguity with the flattening separator - see also the TractusX discussion: Limit Aspect model payloadName’s with single underscore.

Property Serialization Rules

For each Property:

Optional Properties: If a Property is marked as optional and not included, its column value will be null.
Scalar Properties: If the Property’s effective data type is scalar:
- The Property is serialized as a column with the name ${propertyName}.
- The column type is determined by the data type mapping (see Data Type Mappings).
- The value must adhere to the value range defined by the Property’s effective data type and possible Constraints.
Multi-language Properties (rdf:langString):
- Each language variant is serialized as a separate column.
- Column naming follows the pattern ${propertyName}-${language} (hyphen-separated).
- Example: description-en, description-de, description-zh.
Entity Properties: If the Property’s effective data type is an Entity:
- The Entity’s Properties are flattened using the double underscore separator.
- Example: Property address with nested Properties street and city becomes addressstreet and addresscity.
Entity Inheritance: If an Entity extends another Entity:
- All Properties from the Entity and its parent Entities are included.
- Properties are resolved from ?thisEntity samm:extends* [].
Collection Properties: If the Property’s Characteristic is a Collection, List, Set, or Sorted Set:
- For collections of scalar types and complex types (Entities): Each element is represented with the ${collectionName}__${propertyName} (underscore-separated).
- Example: itemsname, itemsprice, itemsname, itemsprice.
Characteristic: If the Property’s Characteristic is samm-c:Either:
- Both left and right alternatives are represented as separate columns.
- Column naming follows ${propertyName}left and ${propertyName}right.
License information: No license headers available when generating example Apache Parquet files from an Aspect model

Denormalization for Collections

When an Aspect contains Properties with Collections:

Each collection element may result in a separate row in the Parquet file to maintain a denormalized structure.
This approach is suitable for analytical workloads where columnar storage and denormalization improve query performance.

Characteristics Not Subject to Serialization

Operations defined in the Aspect Model are not subject to serialization.
Events defined in the Aspect Model are not subject to serialization.

Data Type Mappings

The following table describes how Aspect Model data types are mapped to Apache Parquet primitive types with their logical type annotations where applicable.

Aspect Model data type Corresponding Apache Parquet Type

	Aspect Model data type	Corresponding Apache Parquet Type
Core Types	`xsd:string`	`BYTE_ARRAY` / `FIXED_LEN_BYTE_ARRAY` (if LengthConstraint Trait max value is available)
`xsd:boolean`	`BOOLEAN`
`xsd:decimal`	`DOUBLE`
`xsd:integer`	`INT32`
IEEE Floating-Point Numbers	`xsd:double`	`DOUBLE`
`xsd:float`	`FLOAT`
Time and Date	`xsd:date`	`INT32`
`xsd:time`	`BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)`
`xsd:dateTime`	`INT64`
`xsd:dateTimeStamp`	`INT64`
Recurring and Partial Dates	`xsd:gYear`	`BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)`
`xsd:gMonth`	`BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)`
`xsd:gDay`	`BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)`
`xsd:gYearMonth`	`BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)`
`xsd:gMonthDay`	`BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)`
`xsd:duration`	`BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)`
`xsd:yearMonthDuration`	`BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)`
`xsd:dayTimeDuration`	`BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)`
Limited-Range Integer Numbers	`xsd:byte`	`INT32`
`xsd:short`	`INT32`
`xsd:int`	`INT32`
`xsd:long`	`INT64`
`xsd:unsignedByte`	`INT32`
`xsd:unsignedShort`	`INT32`
`xsd:unsignedInt`	`INT64`
`xsd:unsignedLong`	`INT64`
`xsd:positiveInteger`	`INT32`
`xsd:nonNegativeInteger`	`INT32`
`xsd:negativeInteger`	`INT32`
`xsd:nonPositiveInteger`	`INT32`
Encoded Binary Data	`xsd:hexBinary`	`BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)`
`xsd:base64Binary`	`BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)`
Miscellaneous Types	`xsd:anyURI`	`BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)`
`rdf:langString`	`BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)`

Core Types

xsd:string

BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)

xsd:boolean

BOOLEAN

xsd:decimal

DOUBLE

xsd:integer

INT32

IEEE Floating-Point Numbers

xsd:double

DOUBLE

xsd:float

FLOAT

Time and Date

xsd:date

INT32

xsd:time

BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)

xsd:dateTime

INT64

xsd:dateTimeStamp

INT64

Recurring and Partial Dates

xsd:gYear

BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)

xsd:gMonth

BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)

xsd:gDay

BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)

xsd:gYearMonth

BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)

xsd:gMonthDay

BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)

xsd:duration

BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)

xsd:yearMonthDuration

BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)

xsd:dayTimeDuration

BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)

Limited-Range Integer Numbers

xsd:byte

INT32

xsd:short

INT32

xsd:int

INT32

xsd:long

INT64

xsd:unsignedByte

INT32

xsd:unsignedShort

INT32

xsd:unsignedInt

INT64

xsd:unsignedLong

INT64

xsd:positiveInteger

INT32

xsd:nonNegativeInteger

INT32

xsd:negativeInteger

INT32

xsd:nonPositiveInteger

INT32

Encoded Binary Data

xsd:hexBinary

BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)

xsd:base64Binary

BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)

Miscellaneous Types

xsd:anyURI

BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)

rdf:langString

BYTE_ARRAY / FIXED_LEN_BYTE_ARRAY (if LengthConstraint Trait max value is available)

Example

Aspect Model

# Copyright (c) 2026 Robert Bosch Manufacturing Solutions GmbH

# See the AUTHORS file(s) distributed with this work for additional information regarding authorship.

# This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
# If a copy of the MPL was not distributed with this file, You can obtain one at https://mozilla.org/MPL/2.0/
# SPDX-License-Identifier: MPL-2.0

@prefix samm: <urn:samm:org.eclipse.esmf.samm:meta-model:2.1.0#> .
@prefix samm-c: <urn:samm:org.eclipse.esmf.samm:characteristic:2.1.0#> .
@prefix samm-e: <urn:samm:org.eclipse.esmf.samm:entity:2.1.0#> .
@prefix unit: <urn:samm:org.eclipse.esmf.samm:unit:2.1.0#> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
@prefix : <urn:samm:org.eclipse.esmf:1.0.0#> .

:ExampleAspect a samm:Aspect ;
   samm:preferredName "ExampleAspect"@en ;
   samm:description "Example Aspect for Apache Parquet file generation"@en ;
   samm:properties ( :unsignedLongProperty :unsignedIntProperty :negativeIntegerProperty :nonPositiveIntegerProperty :nonNegativeIntegerProperty :unsignedByteProperty :unsignedShortProperty :longProperty :byteProperty :shortProperty :integerProperty :intProperty :decimalProperty :doubleProperty :floatProperty :booleanProperty :exampleProperty :eitherProperty :lengthConstraintProperty ) ;
   samm:operations ( ) ;
   samm:events ( ) .

:unsignedLongProperty a samm:Property ;
   samm:preferredName "unsignedLongProperty"@en ;
   samm:description "unsignedLongProperty"@en ;
   samm:characteristic :UnsignedLongCharacteristic ;
   samm:exampleValue "1000"^^xsd:unsignedLong .

:unsignedIntProperty a samm:Property ;
   samm:preferredName "unsignedIntProperty"@en ;
   samm:description "unsignedIntProperty"@en ;
   samm:characteristic :UnsignedIntPropertyCharacteristic ;
   samm:exampleValue "4"^^xsd:unsignedInt .

:negativeIntegerProperty a samm:Property ;
   samm:preferredName "negativeIntegerProperty"@en ;
   samm:description "negativeIntegerProperty"@en ;
   samm:characteristic :NegativeIntegerCharacteristic ;
   samm:exampleValue "-10"^^xsd:negativeInteger .

:nonPositiveIntegerProperty a samm:Property ;
   samm:preferredName "nonPositiveIntegerProperty"@en ;
   samm:description "nonPositiveIntegerProperty"@en ;
   samm:characteristic :NonPositiveIntegerCharacteristic ;
   samm:exampleValue "0"^^xsd:nonPositiveInteger .

:nonNegativeIntegerProperty a samm:Property ;
   samm:preferredName "nonNegativeIntegerProperty"@en ;
   samm:description "nonNegativeIntegerProperty"@en ;
   samm:characteristic :NonNegativeIntegerCharacteristic ;
   samm:exampleValue "0"^^xsd:nonNegativeInteger .

:unsignedByteProperty a samm:Property ;
   samm:preferredName "unsignedByteProperty"@en ;
   samm:description "unsignedByteProperty"@en ;
   samm:characteristic :UnsignedByteCharacteristic ;
   samm:exampleValue "42"^^xsd:unsignedByte .

:unsignedShortProperty a samm:Property ;
   samm:preferredName "unsignedShortProperty"@en ;
   samm:description "unsignedShortProperty"@en ;
   samm:characteristic :UnsignedShortCharacteristic ;
   samm:exampleValue "255"^^xsd:unsignedShort .

:longProperty a samm:Property ;
   samm:preferredName "longProperty"@en ;
   samm:description "longProperty"@en ;
   samm:characteristic :LongCharacteristic ;
   samm:exampleValue "1122334455"^^xsd:long .

:byteProperty a samm:Property ;
   samm:preferredName "byteProperty"@en ;
   samm:description "byteProperty"@en ;
   samm:characteristic :ByteCharacteristic ;
   samm:exampleValue "-1"^^xsd:byte .

:shortProperty a samm:Property ;
   samm:preferredName "shortProperty"@en ;
   samm:description "shortProperty"@en ;
   samm:characteristic :ShortCharacteristic ;
   samm:exampleValue "2"^^xsd:short .

:integerProperty a samm:Property ;
   samm:preferredName "integerProperty"@en ;
   samm:description "integerProperty"@en ;
   samm:characteristic :IntegerCharacteristic ;
   samm:exampleValue 10 .

:intProperty a samm:Property ;
   samm:preferredName "intProperty"@en ;
   samm:description "intProperty"@en ;
   samm:characteristic :IntCharacteristic ;
   samm:exampleValue "5"^^xsd:int .

:decimalProperty a samm:Property ;
   samm:preferredName "decimalProperty"@en ;
   samm:characteristic :DecimalCharacteristic ;
   samm:exampleValue "0.5"^^xsd:decimal .

:doubleProperty a samm:Property ;
   samm:preferredName "doubleProperty"@en ;
   samm:characteristic :DoubleCharacteristic ;
   samm:exampleValue "22.189"^^xsd:double .

:floatProperty a samm:Property ;
   samm:preferredName "floatProperty"@en ;
   samm:characteristic :FloatCharacteristic ;
   samm:exampleValue "1.9"^^xsd:float .

:booleanProperty a samm:Property ;
   samm:preferredName "boolean Property"@en ;
   samm:characteristic :BooleanCharacteristic ;
   samm:exampleValue true .

:exampleProperty a samm:Property ;
   samm:characteristic :ExampleCharacteristicList .

:eitherProperty a samm:Property ;
   samm:characteristic :EitherCharacteristic .

:lengthConstraintProperty a samm:Property ;
   samm:preferredName "lengthConstraintProperty"@en ;
   samm:characteristic :LengthTrait1 ;
   samm:exampleValue "testing" .

:UnsignedLongCharacteristic a samm:Characteristic ;
   samm:preferredName "UnsignedLongCharacteristic"@en ;
   samm:description "UnsignedLongCharacteristic"@en ;
   samm:dataType xsd:unsignedLong .

:UnsignedIntPropertyCharacteristic a samm:Characteristic ;
   samm:preferredName "UnsignedIntPropertyCharacteristic"@en ;
   samm:description "UnsignedIntPropertyCharacteristic"@en ;
   samm:dataType xsd:unsignedInt .

:NegativeIntegerCharacteristic a samm:Characteristic ;
   samm:preferredName "NegativeIntegerCharacteristic"@en ;
   samm:description "NegativeIntegerCharacteristic"@en ;
   samm:dataType xsd:negativeInteger .

:NonPositiveIntegerCharacteristic a samm:Characteristic ;
   samm:preferredName "NonPositiveIntegerCharacteristic"@en ;
   samm:description "NonPositiveIntegerCharacteristic"@en ;
   samm:dataType xsd:nonPositiveInteger .

:NonNegativeIntegerCharacteristic a samm:Characteristic ;
   samm:preferredName "NonNegativeIntegerCharacteristic"@en ;
   samm:description "NonNegativeIntegerCharacteristic"@en ;
   samm:dataType xsd:nonNegativeInteger .

:UnsignedByteCharacteristic a samm:Characteristic ;
   samm:preferredName "UnsignedByteCharacteristic"@en ;
   samm:description "UnsignedByteCharacteristic"@en ;
   samm:dataType xsd:unsignedByte .

:UnsignedShortCharacteristic a samm:Characteristic ;
   samm:preferredName "UnsignedShortCharacteristic"@en ;
   samm:description "UnsignedShortCharacteristic"@en ;
   samm:dataType xsd:unsignedShort .

:LongCharacteristic a samm:Characteristic ;
   samm:preferredName "LongCharacteristic"@en ;
   samm:description "LongCharacteristic"@en ;
   samm:dataType xsd:long .

:ByteCharacteristic a samm:Characteristic ;
   samm:preferredName "ByteCharacteristic"@en ;
   samm:description "ByteCharacteristic"@en ;
   samm:dataType xsd:byte .

:ShortCharacteristic a samm:Characteristic ;
   samm:preferredName "ShortCharacteristic"@en ;
   samm:description "ShortCharacteristic"@en ;
   samm:dataType xsd:short .

:IntegerCharacteristic a samm:Characteristic ;
   samm:preferredName "integerProperty"@en ;
   samm:dataType xsd:integer .

:IntCharacteristic a samm:Characteristic ;
   samm:preferredName "IntCharacteristic"@en ;
   samm:dataType xsd:int .

:DecimalCharacteristic a samm:Characteristic ;
   samm:preferredName "Decimal Characteristic"@en ;
   samm:dataType xsd:decimal .

:DoubleCharacteristic a samm:Characteristic ;
   samm:preferredName "DoubleCharacteristic"@en ;
   samm:dataType xsd:double .

:FloatCharacteristic a samm:Characteristic ;
   samm:preferredName "FloatCharacteristic"@en ;
   samm:dataType xsd:float .

:BooleanCharacteristic a samm:Characteristic ;
   samm:dataType xsd:boolean .

:ExampleCharacteristicList a samm-c:List ;
   samm:dataType :ExampleEntity .

:EitherCharacteristic a samm-c:Either ;
   samm-c:left :LeftCharacteristicExample ;
   samm-c:right :RightCharacteristicExample .

:LengthTrait1 a samm-c:Trait ;
   samm:preferredName "LengthTrait1"@en ;
   samm-c:baseCharacteristic :ExampleLengthCharacteristic ;
   samm-c:constraint :LengthConstraintExample .

:ExampleEntity a samm:Entity ;
   samm:preferredName "ExampleEntity"@en ;
   samm:properties ( :booleanProperty :anyURIProperty :base64BinaryProperty :hexBinaryProperty :gMonthDayProperty :gYearMonthProperty :gYearProperty :gMonthProperty :gDayProperty :dayTimeDurationProperty :yearMonthDurationProperty :durationProperty :dateTimeStampProperty :dateTimeProperty :timeProperty :dateProperty :stringProperty :dateTimePropertyWithTimeZone :langStringProperty ) .

:LeftCharacteristicExample a samm:Characteristic ;
   samm:dataType xsd:string .

:RightCharacteristicExample a samm:Characteristic ;
   samm:dataType xsd:string .

:ExampleLengthCharacteristic a samm:Characteristic ;
   samm:dataType xsd:string .

:LengthConstraintExample a samm-c:LengthConstraint ;
   samm:preferredName "LengthConstraintExample"@en ;
   samm-c:minValue "1"^^xsd:nonNegativeInteger ;
   samm-c:maxValue "10"^^xsd:nonNegativeInteger .

:anyURIProperty a samm:Property ;
   samm:preferredName "anyURIProperty"@en ;
   samm:description "anyURIProperty"@en ;
   samm:characteristic :AnyURICharacteristic ;
   samm:exampleValue "http://www.example.com"^^xsd:anyURI .

:base64BinaryProperty a samm:Property ;
   samm:preferredName "base64BinaryProperty"@en ;
   samm:description "base64BinaryProperty"@en ;
   samm:characteristic :Base64BinaryCharacteristic ;
   samm:exampleValue "VGhpcyBpcyBhIHRlc3Q="^^xsd:base64Binary .

:hexBinaryProperty a samm:Property ;
   samm:preferredName "hexBinaryProperty"@en ;
   samm:description "hexBinaryProperty"@en ;
   samm:characteristic :HexBinaryCharacteristic ;
   samm:exampleValue "4A3B"^^xsd:hexBinary .

:gMonthDayProperty a samm:Property ;
   samm:preferredName "gMonthDayProperty"@en ;
   samm:description "gMonthDayProperty"@en ;
   samm:characteristic :GMonthDayCharacteristic ;
   samm:exampleValue "--11-21"^^xsd:gMonthDay .

:gYearMonthProperty a samm:Property ;
   samm:preferredName "gYearMonthProperty"@en ;
   samm:description "gYearMonthProperty"@en ;
   samm:characteristic :GYearMonthCharacteristic ;
   samm:exampleValue "2025-11"^^xsd:gYearMonth .

:gYearProperty a samm:Property ;
   samm:preferredName "gYearProperty"@en ;
   samm:description "gYearProperty"@en ;
   samm:characteristic :GYearCharacteristic ;
   samm:exampleValue "2025"^^xsd:gYear .

:gMonthProperty a samm:Property ;
   samm:preferredName "gMonthProperty"@en ;
   samm:description "gMonthProperty"@en ;
   samm:characteristic :GMonthCharacteristic ;
   samm:exampleValue "--07"^^xsd:gMonth .

:gDayProperty a samm:Property ;
   samm:preferredName "gDayProperty"@en ;
   samm:description "gDayProperty"@en ;
   samm:characteristic :GDayCharacteristic ;
   samm:exampleValue "---05"^^xsd:gDay .

:dayTimeDurationProperty a samm:Property ;
   samm:preferredName "dayTimeDurationProperty"@en ;
   samm:description "dayTimeDurationProperty"@en ;
   samm:characteristic :DayTimeDurationCharacteristic ;
   samm:exampleValue "P10D"^^xsd:dayTimeDuration .

:yearMonthDurationProperty a samm:Property ;
   samm:preferredName "yearMonthDurationProperty"@en ;
   samm:description "yearMonthDurationProperty"@en ;
   samm:characteristic :YearMonthDurationCharacteristic ;
   samm:exampleValue "P2Y"^^xsd:yearMonthDuration .

:durationProperty a samm:Property ;
   samm:preferredName "durationProperty"@en ;
   samm:description "durationProperty"@en ;
   samm:characteristic :DurationCharacteristic ;
   samm:exampleValue "P10D"^^xsd:duration .

:dateTimeStampProperty a samm:Property ;
   samm:preferredName "dateTimeStampProperty"@en ;
   samm:description "dateTimeStampProperty"@en ;
   samm:characteristic :DateTimeStampCharacteristic ;
   samm:exampleValue "2025-11-21T14:30:00Z"^^xsd:dateTimeStamp .

:dateTimeProperty a samm:Property ;
   samm:preferredName "dateTimeProperty"@en ;
   samm:description "dateTimeProperty"@en ;
   samm:characteristic :DateTimeCharacteristic ;
   samm:exampleValue "2025-11-21T14:30:00"^^xsd:dateTime .

:timeProperty a samm:Property ;
   samm:preferredName "timeProperty"@en ;
   samm:description "timeProperty"@en ;
   samm:characteristic :TimeCharacteristic ;
   samm:exampleValue "14:30:15.123"^^xsd:time .

:dateProperty a samm:Property ;
   samm:preferredName "dateProperty"@en ;
   samm:description "dateProperty"@en ;
   samm:characteristic :DateCharacteristic ;
   samm:exampleValue "2025-10-14"^^xsd:date .

:stringProperty a samm:Property ;
   samm:preferredName "stringProperty"@en ;
   samm:description "stringProperty"@en ;
   samm:characteristic :StringCharacteristic ;
   samm:exampleValue "exampleString" .

:dateTimePropertyWithTimeZone a samm:Property ;
   samm:preferredName "dateTimePropertyWithTimeZone"@en ;
   samm:description "dateTimePropertyWithTimeZone"@en ;
   samm:characteristic :DateTimeCharacteristic ;
   samm:exampleValue "2025-10-14T09:37:33.098+05:30"^^xsd:dateTime .

:langStringProperty a samm:Property ;
   samm:preferredName "langStringProperty"@en ;
   samm:description "langStringProperty"@en ;
   samm:characteristic :LangStringCharacteristic ;
   samm:exampleValue "sample lang string"@en .

:AnyURICharacteristic a samm:Characteristic ;
   samm:preferredName "AnyURICharacteristic"@en ;
   samm:description "AnyURICharacteristic"@en ;
   samm:dataType xsd:anyURI .

:Base64BinaryCharacteristic a samm:Characteristic ;
   samm:preferredName "Base64BinaryCharacteristic"@en ;
   samm:description "Base64BinaryCharacteristic"@en ;
   samm:dataType xsd:base64Binary .

:HexBinaryCharacteristic a samm:Characteristic ;
   samm:preferredName "HexBinaryCharacteristic"@en ;
   samm:description "HexBinaryCharacteristic"@en ;
   samm:dataType xsd:hexBinary .

:GMonthDayCharacteristic a samm:Characteristic ;
   samm:preferredName "GMonthDayCharacteristic"@en ;
   samm:description "GMonthDayCharacteristic"@en ;
   samm:dataType xsd:gMonthDay .

:GYearMonthCharacteristic a samm:Characteristic ;
   samm:preferredName "GYearMonthCharacteristic"@en ;
   samm:description "GYearMonthCharacteristic"@en ;
   samm:dataType xsd:gYearMonth .

:GYearCharacteristic a samm:Characteristic ;
   samm:preferredName "GYearCharacteristic"@en ;
   samm:description "GYearCharacteristic"@en ;
   samm:dataType xsd:gYear .

:GMonthCharacteristic a samm:Characteristic ;
   samm:preferredName "GMonthCharacteristic"@en ;
   samm:description "GMonthCharacteristic"@en ;
   samm:dataType xsd:gMonth .

:GDayCharacteristic a samm:Characteristic ;
   samm:preferredName "GDayCharacteristic"@en ;
   samm:description "GDayCharacteristic"@en ;
   samm:dataType xsd:gDay .

:DayTimeDurationCharacteristic a samm:Characteristic ;
   samm:preferredName "DayTimeDurationCharacteristic"@en ;
   samm:description "DayTimeDurationCharacteristic"@en ;
   samm:dataType xsd:dayTimeDuration .

:YearMonthDurationCharacteristic a samm:Characteristic ;
   samm:preferredName "YearMonthDurationCharacteristic"@en ;
   samm:description "YearMonthDurationCharacteristic"@en ;
   samm:dataType xsd:yearMonthDuration .

:DurationCharacteristic a samm:Characteristic ;
   samm:preferredName "DurationCharacteristic"@en ;
   samm:description "DurationCharacteristic"@en ;
   samm:dataType xsd:duration .

:DateTimeStampCharacteristic a samm:Characteristic ;
   samm:preferredName "DateTimeStampCharacteristic"@en ;
   samm:description "DateTimeStampCharacteristic"@en ;
   samm:dataType xsd:dateTimeStamp .

:DateTimeCharacteristic a samm:Characteristic ;
   samm:preferredName "DateTimeCharacteristic"@en ;
   samm:description "DateTimeCharacteristic"@en ;
   samm:dataType xsd:dateTime .

:TimeCharacteristic a samm:Characteristic ;
   samm:preferredName "TimeCharacteristic"@en ;
   samm:description "TimeCharacteristic"@en ;
   samm:dataType xsd:time .

:DateCharacteristic a samm:Characteristic ;
   samm:preferredName "DateCharacteristic"@en ;
   samm:description "DateCharacteristic"@en ;
   samm:dataType xsd:date .

:StringCharacteristic a samm:Characteristic ;
   samm:preferredName "StringCharacteristic"@en ;
   samm:description "StringCharacteristic"@en ;
   samm:dataType xsd:string .

:LangStringCharacteristic a samm:Characteristic ;
   samm:preferredName "LangStringCharacteristic"@en ;
   samm:description "LangStringCharacteristic"@en ;
   samm:dataType rdf:langString .

Parquet Schema

The above Aspect Model would result in the Parquet schema structure ExampleAspect.parquet

Limitations and Considerations

Aspect Model data String data type To Apache Parquet FIXED_LEN_BYTE_ARRAY / BYTE_ARRAY : Aspect Model data String data type will be represented as Apache Parquet FIXED_LEN_BYTE_ARRAY only if there is a LengthConstraint Trait max value defined for the given Property or else it will be represented as Apache Parquet BYTE_ARRAY irrespective of the encoding type.
Order of collection data: Order of collection data is not relevant when creating the Apache Parquet file. This is because, once the data is flattened, no order-related information is retained since only one element per collection will be created when generating a sample Apache Parquet file from an Aspect model.
Timezone Handling: For xsd:dateTime and xsd:dateTimeStamp:
- When timezone information is present, timestamps are normalized to UTC.
- When no timezone information is present, timestamps are stored as-is.
Property Naming: To avoid ambiguity:
- Use single underscores (_) in Property names.
- The double underscore (__) is reserved for representing nested hierarchies.
- Hyphens (-) are used to separate language codes in rdf:langString columns.

Mapping to Apache Parquet

Overview

Rules for the construction of Apache Parquet files matching an Aspect Model

Flattening Strategy

Property Serialization Rules

Denormalization for Collections

Characteristics Not Subject to Serialization

Data Type Mappings

Example

Aspect Model

Parquet Schema

Limitations and Considerations

References