CarbonData¶
CarbonData is a new Apache Hadoop native data-store format. CarbonData allows faster interactive queries over PetaBytes of data using advanced columnar storage, index, compression, and encoding techniques to improve computing efficiency. In addition, CarbonData is also a high-performance analysis engine that integrates data sources with Spark.
Figure 1 Basic architecture of CarbonData¶
The purpose of using CarbonData is to provide quick response to ad hoc queries of big data. Essentially, CarbonData is an Online Analytical Processing (OLAP) engine, which stores data using tables similar to those in Relational Database Management System (RDBMS). You can import more than 10 TB data to tables created in CarbonData format, and CarbonData automatically organizes and stores data using the compressed multi-dimensional indexes. After data is loaded to CarbonData, CarbonData responds to ad hoc queries in seconds.
CarbonData integrates data sources into the Spark ecosystem. You can use Spark SQL to query and analyze data, or use the third-party tool ThriftServer provided by Spark to connect to Spark SQL.
CarbonData features
SQL: CarbonData is compatible with Spark SQL and supports SQL query operations performed on Spark SQL.
Simple Table dataset definition: CarbonData allows you to define and create datasets by using user-friendly Data Definition Language (DDL) statements. CarbonData DDL is flexible and easy to use, and can define complex tables.
Easy data management: CarbonData provides various data management functions for data loading and maintenance. It can load historical data and incrementally load new data. The loaded data can be deleted according to the loading time and specific data loading operations can be canceled.
CarbonData file format is a columnar store in HDFS. It has many features that a modern columnar format has, such as splittable and compression schema.
Unique features of CarbonData
Stores data along with index: Significantly accelerates query performance and reduces the I/O scans and CPU resources, when there are filters in the query. CarbonData index consists of multiple levels of indices. A processing framework can leverage this index to reduce the task it needs to schedule and process, and it can also perform skip scan in more finer grain unit (called blocklet) in task side scanning instead of scanning the whole file.
Operable encoded data: Through supporting efficient compression and global encoding schemes, CarbonData can query on compressed/encoded data. The data can be converted just before returning the results to the users, which is "late materialized".
Supports various use cases with one single data format: like interactive OLAP-style query, Sequential Access (big scan), and Random Access (narrow scan).
Key technologies and advantages of CarbonData
Quick query response: CarbonData features high-performance query. The query speed of CarbonData is 10 times of that of Spark SQL. It uses dedicated data formats and applies multiple index technologies, global dictionary code, and multiple push-down optimizations, providing quick response to TB-level data queries.
Efficient data compression: CarbonData compresses data by combining the lightweight and heavyweight compression algorithms. This significantly saves 60% to 80% data storage space and the hardware storage cost.
For details about CarbonData architecture and principles, see https://carbondata.apache.org/.