westonpace commented on a change in pull request #85: URL: https://github.com/apache/arrow-cookbook/pull/85#discussion_r737836447
########## File path: cpp/source/datasets.rst ########## @@ -0,0 +1,67 @@ +.. 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. + +============================ +Reading and Writing Datasets +============================ + +This section contains a number of recipes for reading and writing +datasets. Datasets are a collection of one or more files containing +tabular data. + +.. contents:: + +Read a Partitioned Dataset +========================== + +The individual data files that make up a dataset will often be +distributed across several different directories according to some +kind of partitioning scheme. + +This simplifies management of the data and also allows for partial +reads of the dataset by inspecting the file paths and utilizing the +guarantess provided by the partitioning scheme. + +This recipe demonstrates the basics of reading a partitioned dataset. +First let us inspect our data: + +.. recipe:: ../code/datasets.cc ListPartitionedDataset + :caption: A listing of files in our dataset + :dedent: 2 + +.. note:: + + This partitioning scheme of key=value is referred to as "hive" + partitioning within Arrow. + +Now that we have a filesystem and a selector we can go ahead and create +a dataset. To do this we need to pick a format and a partitioning +scheme. Once we have all of the pieces we need we can create an +arrow::dataset::Dataset instance. + +.. recipe:: ../code/datasets.cc CreatingADataset + :caption: Creating an arrow::dataset::Dataset instance + :dedent: 2 + +Once we have a dataset object we can read in the data. Reading the data +from a dataset is sometimes called "scanning" the dataset and the object +we use to do this is an arrow::dataset::Scanner. The following snippet Review comment: It's great! Arrow's habit of being an intersection for multiple disciplines means that working on it is to experience a melting pot of vocabulary. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: github-unsubscr...@arrow.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
