Apache Parquet

Apache Parquet is a column-oriented storage format for Hadoop. Hadoop is a free, Java-based programming framework that supports the processing of large data sets in a distributed computing environment. Parquet is optimized to work with complex data in bulk and includes methods for efficient data compression and encoding types.

Typically, data is stored in a row-oriented fashion. Even in databases, data is conventionally stored in this way and is optimized for working with one record at a time. Parquet uses a record-shredding and assembly algorithm to break down data and reassemble it so values in each column are physically stored in contiguous memory locations. Data stored by column in this serialized method allows for efficient searches across massive data sets. Since Hadoop is made for big data, columnar storage is a complementary technology.  

Storing data in a columnar format provides benefits such as:

• More efficient compression due to space saved by the columnar format.
• Likeness of the data of columns enables data compression for the specific type of data.
• Queries searching specific column values need not read the entire row's data, making searches faster.
• Different encoding can be used per column, allowing for better compression to be used as it is developed.

Parquet’s Apache Thrift framework increases flexibility, to allow working with C++, Java and Python.
Parquet is compatible with the majority of data processing frameworks in Hadoop. Other columnar storage file formats include ORC, RCFile and optimized RCFile.

Parquet is a top-level project sponsored by the Apache Software Foundation (ASF). The project originated as a joint effort of Twitter and Cloudera.