What is Dataset?
A dataset is a collection of strongly-typed JVM (Java Virtual Machine) objects that can be queried using a functional programming paradigm, similar to a SQL table or a R/Python DataFrame. A Dataset can be thought of as a strongly-typed DataFrame.
Datasets provide compile-time type safety, which means that if you try to store an incompatible type in a dataset, the code will not compile. This allows for better error-checking and can help to prevent runtime errors. Datasets also leverage the Spark’s Catalyst optimizer, which can optimize the execution plan of a query and improve performance.
Datasets are typically used in big data processing and analytics, such as Apache Spark and Apache Flink. They can handle more complex data structures and operations, and they are well-suited for use cases where performance and type safety are important.
You can create a dataset from an existing data source, like a file, or by creating a new one from a collection of objects. You can also transform a dataset by applying various operations like filter, map, reduce, and more.
Datasets are more memory efficient than RDDs (Resilient Distributed Datasets) and provide a higher-level API that makes it easy to work with structured and semi-structured data.
What is DataFrame?
A DataFrame is a 2D size-mutable, tabular data structure with rows and columns. It is similar to a table in a relational database or a data frame in R/Python, and it can hold any data type. DataFrames are implemented on top of RDDs (Resilient Distributed Datasets) and optimized for performance.
DataFrames are a fundamental concept in big data processing and analytics, such as Apache Spark and Apache Flink, and are widely used for structured and semi-structured data. They can be created from various data sources such as structured data files, Hive tables, external databases, or existing RDDs.
DataFrames have a wide variety of APIs and are more flexible when it comes to data manipulation, unlike datasets. They can be transformed and manipulated by applying various operations like filter, groupby, join, select and more. DataFrames are generally faster than Datasets because they use code generation instead of the JVM, but they are not type-safe, meaning that it’s possible to get runtime errors due to type mismatch.
DataFrames leverage lazy evaluation, which means that it will not perform any computation until an action is performed on the data. This allows for better memory management. DataFrames are also optimized by the Catalyst optimizer, a query optimizer that can optimize the execution plan of a query and improve performance.
In summary, DataFrames are a powerful and flexible data structure that provides a high-level API for working with structured and semi-structured data, They are widely used in big data processing and analytics, and are more efficient and faster than Datasets but lack the type safety feature.
Dataset VS DataFrame
A Dataset and a DataFrame are both used for storing and manipulating large amounts of data in a structured way, but they have some key differences:
- Data Type: A DataFrame is a 2D size-mutable, tabular data structure with rows and columns. It can hold any data type, whereas a Dataset is a collection of strongly-typed JVM objects, and it is type-safe.
- Performance: A DataFrame is generally faster than a Dataset when it comes to performance because the latter uses the Java Virtual Machine (JVM) and the former uses code generation. DataFrames are implemented on top of RDDs (Resilient Distributed Datasets) and optimized for performance.
- API: DataFrames have a wider variety of APIs and are more flexible when it comes to data manipulation, whereas Datasets have a more limited set of APIs, but they are more concise and expressive.
- Type Safety: Datasets provide compile-time type safety, which means that if you try to store an incompatible type in a Dataset, the code will not compile. DataFrames, on the other hand, are not type-safe and may lead to runtime errors.
- Memory Management: DataFrames leverage lazy evaluation, which means that it will not perform any computation until an action is performed on the data. This allows for better memory management, whereas Datasets perform immediate evaluation and consume more memory.
- Use Case: DataFrames are generally used for structured and semi-structured data, whereas Datasets are used for strongly-typed, object-oriented programming and can handle more complex data structures and operations.
In a nutshell, DataFrames are more flexible and efficient in terms of performance, while Datasets are more type-safe and expressive, but with a limited set of APIs and more memory consumption.
More to Read
- Relational Database Benefits and Limitations
- Relational Vs Non Relational Database
- Data Warehouse vs Database
- Dataset vs Database
- Database vs DataFrame
- Primary Key vs Foreign Key
- Primary Key vs Candidate Key
- 13 Examples of Relational Database
- Relational Database Vs. Object-Oriented Database
- 9 Types of Databases
- Distributed Database
- Operational Database
- Personal Database
- Graph Databases
- Centralized Database