org.apache.hadoop.hive.ql.io.orc.package-info Maven / Gradle / Ivy
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* The Optimized Row Columnar (ORC) File Format.
*
* This format:
*
* - Decomposes complex column types into primitives
* - Uses type-specific encoders for each column
*
* - Dictionary encodings for low cardinality columns
* - Run length encoding of data
* - variable length encoding of integers
*
*
* - Divides file into large stripes
* - Each stripe includes light-weight indexes that enable the reader to
* skip large sets of rows that don't satisfy the filter condition
* - A file footer that contains meta-information about file
*
* - Precise byte range for each stripe
* - Type information for the file
* - Any user meta-information
*
*
* - Seek to row number is implemented to support secondary indexes
* - Support for additional generic compression: LZO, SNAPPY, ZLIB.
*
*
*
* Format:
*
* {@code
* HEADER (3 bytes) "ORC"
* STRIPE (0 or more stripes)
* FILE-FOOTER
* POST SCRIPT
* PS LENGTH (1 byte)
* }
*
*
*
*
* Stripe:
*
* {@code
* INDEX-STREAM (0 or more)
* DATA-STREAM (0 or more)
* STRIPE-FOOTER
* }
*
*
*/
package org.apache.hadoop.hive.ql.io.orc;