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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 and a C++ library for reading and writing 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. But the C++ library only writes the original (Hive 0.11) version of ORC files, and will be extened in the future.

Releases:

The current build status:

Bug tracking: Apache Jira

The subdirectories are:

  • c++ - the c++ reader and writer
  • 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