Apache ORC

ORC is a self-describing type-aware columnar file format designed for Hadoop workloads. It is optimized for large streaming reads, but with integrated support for finding required rows quickly. Storing data in a columnar format lets the reader read, decompress, and process only the values that are required for the current query. Because ORC files are type-aware, the writer chooses the most appropriate encoding for the type and builds an internal index as the file is written. Predicate pushdown uses those indexes to determine which stripes in a file need to be read for a particular query and the row indexes can narrow the search to a particular set of 10,000 rows. ORC supports the complete set of types in Hive, including the complex types: structs, lists, maps, and unions.

ORC File Library

This project includes both a Java library for reading and writing and a C++ library for reading the Optimized Row Columnar (ORC) file format. The C++ and Java libraries are completely independent of each other and will each read all versions of ORC files.

The current build status:

• Master branch
• Pull Requests

The subdirectories are:

• c++ - the c++ reader
• docker - docker scripts to build and test on various linuxes
• examples - various ORC example files that are used to test compatibility
• java - the java reader and writer
• proto - the protocol buffer definition for the ORC metadata
• site - the website and documentation
• tools - the c++ tools for reading and inspecting ORC files

Building

• Install java 1.7 or higher
• Install maven 3 or higher
• Install cmake

To build a release version with debug information:

% mkdir build
% cd build
% cmake ..
% make package
% make test-out

To build a debug version:

% mkdir build
% cd build
% cmake .. -DCMAKE_BUILD_TYPE=DEBUG
% make package
% make test-out

To build a release version without debug information:

% mkdir build
% cd build
% cmake .. -DCMAKE_BUILD_TYPE=RELEASE
% make package
% make test-out

To build only the Java library:

% cd java
% mvn package

To build only the C++ library:

% mkdir build
% cd build
% cmake .. -DBUILD_JAVA=OFF
% make package
% make test-out