# [Apache ORC](https://orc.apache.org/) 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 extended in the future. Releases: * Latest: <a href="http://orc.apache.org/releases">Apache ORC releases</a> * Maven Central: <a href="http://search.maven.org/#search%7Cga%7C1%7Cg%3A%22org.apache.orc%22">![Maven Central](https://maven-badges.herokuapp.com/maven-central/org.apache.orc/orc/badge.svg)</a> * Downloads: <a href="http://orc.apache.org/downloads">Apache ORC downloads</a> The current build status: * Master branch <a href="https://travis-ci.org/apache/orc/branches"> ![master build status](https://travis-ci.org/apache/orc.svg?branch=master)</a> * <a href="https://travis-ci.org/apache/orc/pull_requests">Pull Requests</a> Bug tracking: <a href="http://orc.apache.org/bugs">Apache Jira</a> The subdirectories are: * c++ - the c++ reader and writer * cmake_modules - the cmake modules * 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 * snap - the script to build [snaps](https://snapcraft.io/) of the ORC tools * tools - the c++ tools for reading and inspecting ORC files ### Building * Install java 1.8 or higher * Install maven 3 or higher * Install cmake To build a release version with debug information: ```shell % mkdir build % cd build % cmake .. % make package % make test-out ``` To build a debug version: ```shell % mkdir build % cd build % cmake .. -DCMAKE_BUILD_TYPE=DEBUG % make package % make test-out ``` To build a release version without debug information: ```shell % mkdir build % cd build % cmake .. -DCMAKE_BUILD_TYPE=RELEASE % make package % make test-out ``` To build only the Java library: ```shell % cd java % ./mvnw package ``` To build only the C++ library: ```shell % mkdir build % cd build % cmake .. -DBUILD_JAVA=OFF % make package % make test-out ```