Java tutorial
/** * * 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. */ package com.google.cloud.bigtable.mapreduce; import java.io.IOException; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.Path; import org.apache.hadoop.hbase.HBaseConfiguration; import org.apache.hadoop.hbase.classification.InterfaceAudience; import org.apache.hadoop.hbase.classification.InterfaceStability; import org.apache.hadoop.hbase.client.Result; import org.apache.hadoop.hbase.client.Scan; import org.apache.hadoop.hbase.filter.Filter; import org.apache.hadoop.hbase.filter.IncompatibleFilterException; import org.apache.hadoop.hbase.filter.PrefixFilter; import org.apache.hadoop.hbase.filter.RegexStringComparator; import org.apache.hadoop.hbase.filter.RowFilter; import org.apache.hadoop.hbase.filter.CompareFilter.CompareOp; import org.apache.hadoop.hbase.io.ImmutableBytesWritable; import org.apache.hadoop.hbase.mapreduce.IdentityTableMapper; import org.apache.hadoop.hbase.mapreduce.TableInputFormat; import org.apache.hadoop.hbase.util.Bytes; import org.apache.hadoop.mapreduce.Job; import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat; import org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat; import org.apache.hadoop.util.GenericOptionsParser; /** * Export an HBase table. * Writes content to sequence files up in HDFS. Use {@link com.google.cloud.bigtable.mapreduce.Import} to read it * back in again. * * @author sduskis * @version $Id: $Id */ @InterfaceAudience.Public @InterfaceStability.Stable public class Export { private static final Log LOG = LogFactory.getLog(Export.class); final static String NAME = "export"; final static String RAW_SCAN = "hbase.mapreduce.include.deleted.rows"; final static String EXPORT_BATCHING = "hbase.export.scanner.batch"; /** * Sets up the actual job. * * @param conf The current configuration. * @param args The command line parameters. * @return The newly created job. * @throws java.io.IOException When setting up the job fails. */ public static Job createSubmittableJob(Configuration conf, String[] args) throws IOException { String tableName = args[0]; Path outputDir = new Path(args[1]); Job job = new Job(conf, NAME + "_" + tableName); job.setJobName(NAME + "_" + tableName); job.setJarByClass(Export.class); // Set optional scan parameters Scan s = getConfiguredScanForJob(conf, args); IdentityTableMapper.initJob(tableName, s, IdentityTableMapper.class, job); // No reducers. Just write straight to output files. job.setNumReduceTasks(0); job.setOutputFormatClass(SequenceFileOutputFormat.class); job.setOutputKeyClass(ImmutableBytesWritable.class); job.setOutputValueClass(Result.class); FileOutputFormat.setOutputPath(job, outputDir); // job conf doesn't contain the conf so doesn't have a default fs. return job; } private static Scan getConfiguredScanForJob(Configuration conf, String[] args) throws IOException { Scan s = new Scan(); // Optional arguments. // Set Scan Versions int versions = args.length > 2 ? Integer.parseInt(args[2]) : 1; s.setMaxVersions(versions); // Set Scan Range long startTime = args.length > 3 ? Long.parseLong(args[3]) : 0L; long endTime = args.length > 4 ? Long.parseLong(args[4]) : Long.MAX_VALUE; s.setTimeRange(startTime, endTime); // Set cache blocks s.setCacheBlocks(false); // set Start and Stop row if (conf.get(TableInputFormat.SCAN_ROW_START) != null) { s.setStartRow(Bytes.toBytes(conf.get(TableInputFormat.SCAN_ROW_START))); } if (conf.get(TableInputFormat.SCAN_ROW_STOP) != null) { s.setStopRow(Bytes.toBytes(conf.get(TableInputFormat.SCAN_ROW_STOP))); } // Set Scan Column Family boolean raw = Boolean.parseBoolean(conf.get(RAW_SCAN)); if (raw) { s.setRaw(raw); } if (conf.get(TableInputFormat.SCAN_COLUMN_FAMILY) != null) { s.addFamily(Bytes.toBytes(conf.get(TableInputFormat.SCAN_COLUMN_FAMILY))); } // Set RowFilter or Prefix Filter if applicable. Filter exportFilter = getExportFilter(args); if (exportFilter != null) { LOG.info("Setting Scan Filter for Export."); s.setFilter(exportFilter); } int batching = conf.getInt(EXPORT_BATCHING, -1); if (batching != -1) { try { s.setBatch(batching); } catch (IncompatibleFilterException e) { LOG.error("Batching could not be set", e); } } LOG.info("versions=" + versions + ", starttime=" + startTime + ", endtime=" + endTime + ", keepDeletedCells=" + raw); return s; } private static Filter getExportFilter(String[] args) { Filter exportFilter = null; String filterCriteria = (args.length > 5) ? args[5] : null; if (filterCriteria == null) return null; if (filterCriteria.startsWith("^")) { String regexPattern = filterCriteria.substring(1, filterCriteria.length()); exportFilter = new RowFilter(CompareOp.EQUAL, new RegexStringComparator(regexPattern)); } else { exportFilter = new PrefixFilter(Bytes.toBytes(filterCriteria)); } return exportFilter; } /* * @param errorMsg Error message. Can be null. */ private static void usage(final String errorMsg) { if (errorMsg != null && errorMsg.length() > 0) { System.err.println("ERROR: " + errorMsg); } System.err.println("Usage: Export [-D <property=value>]* <tablename> <outputdir> [<versions> " + "[<starttime> [<endtime>]] [^[regex pattern] or [Prefix] to filter]]\n"); System.err.println(" Note: -D properties will be applied to the conf used. "); System.err.println(" For example: "); System.err.println(" -D mapreduce.output.fileoutputformat.compress=true"); System.err.println( " -D mapreduce.output.fileoutputformat.compress.codec=org.apache.hadoop.io.compress.GzipCodec"); System.err.println(" -D mapreduce.output.fileoutputformat.compress.type=BLOCK"); System.err.println(" Additionally, the following SCAN properties can be specified"); System.err.println(" to control/limit what is exported.."); System.err.println(" -D " + TableInputFormat.SCAN_COLUMN_FAMILY + "=<familyName>"); System.err.println(" -D " + RAW_SCAN + "=true"); System.err.println(" -D " + TableInputFormat.SCAN_ROW_START + "=<ROWSTART>"); System.err.println(" -D " + TableInputFormat.SCAN_ROW_STOP + "=<ROWSTOP>"); System.err.println( "For performance consider the following properties:\n" + " -Dhbase.client.scanner.caching=100\n" + " -Dmapreduce.map.speculative=false\n" + " -Dmapreduce.reduce.speculative=false"); System.err.println("For tables with very wide rows consider setting the batch size as below:\n" + " -D" + EXPORT_BATCHING + "=10"); } /** * Main entry point. * * @param args The command line parameters. * @throws java.lang.Exception When running the job fails. */ public static void main(String[] args) throws Exception { Configuration conf = HBaseConfiguration.create(); String[] otherArgs = new GenericOptionsParser(conf, args).getRemainingArgs(); if (otherArgs.length < 2) { usage("Wrong number of arguments: " + otherArgs.length); System.exit(-1); } Job job = createSubmittableJob(conf, otherArgs); System.exit(job.waitForCompletion(true) ? 0 : 1); } }