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 org.apache.cassandra.hadoop.cql3; import java.io.IOException; import java.nio.ByteBuffer; import java.util.List; import org.apache.cassandra.hadoop.ConfigHelper; import org.apache.cassandra.hadoop.HadoopCompat; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.FileSystem; import org.apache.hadoop.mapred.JobConf; import org.apache.hadoop.mapreduce.JobContext; import org.apache.hadoop.mapreduce.OutputCommitter; import org.apache.hadoop.mapreduce.OutputFormat; import org.apache.hadoop.mapreduce.RecordWriter; import org.apache.hadoop.mapreduce.TaskAttemptContext; import org.apache.hadoop.util.Progressable; /** * The <code>CqlBulkOutputFormat</code> acts as a Hadoop-specific * OutputFormat that allows reduce tasks to store keys (and corresponding * bound variable values) as CQL rows (and respective columns) in a given * table. * * <p> * As is the case with the {@link org.apache.cassandra.hadoop.cql3.CqlOutputFormat}, * you need to set the prepared statement in your * Hadoop job Configuration. The {@link CqlConfigHelper} class, through its * {@link ConfigHelper#setOutputPreparedStatement} method, is provided to make this * simple. * you need to set the Keyspace. The {@link ConfigHelper} class, through its * {@link ConfigHelper#setOutputColumnFamily} method, is provided to make this * simple. * </p> */ public class CqlBulkOutputFormat extends OutputFormat<Object, List<ByteBuffer>> implements org.apache.hadoop.mapred.OutputFormat<Object, List<ByteBuffer>> { private static final String OUTPUT_CQL_SCHEMA_PREFIX = "cassandra.table.schema."; private static final String OUTPUT_CQL_INSERT_PREFIX = "cassandra.table.insert."; private static final String DELETE_SOURCE = "cassandra.output.delete.source"; private static final String TABLE_ALIAS_PREFIX = "cqlbulkoutputformat.table.alias."; /** Fills the deprecated OutputFormat interface for streaming. */ @Deprecated public CqlBulkRecordWriter getRecordWriter(FileSystem filesystem, JobConf job, String name, Progressable progress) throws IOException { return new CqlBulkRecordWriter(job, progress); } /** * Get the {@link RecordWriter} for the given task. * * @param context * the information about the current task. * @return a {@link RecordWriter} to write the output for the job. * @throws IOException */ public CqlBulkRecordWriter getRecordWriter(final TaskAttemptContext context) throws IOException, InterruptedException { return new CqlBulkRecordWriter(context); } @Override public void checkOutputSpecs(JobContext context) { checkOutputSpecs(HadoopCompat.getConfiguration(context)); } private void checkOutputSpecs(Configuration conf) { if (ConfigHelper.getOutputKeyspace(conf) == null) { throw new UnsupportedOperationException("you must set the keyspace with setTable()"); } } /** Fills the deprecated OutputFormat interface for streaming. */ @Deprecated public void checkOutputSpecs(org.apache.hadoop.fs.FileSystem filesystem, org.apache.hadoop.mapred.JobConf job) throws IOException { checkOutputSpecs(job); } @Override public OutputCommitter getOutputCommitter(TaskAttemptContext context) throws IOException, InterruptedException { return new NullOutputCommitter(); } public static void setTableSchema(Configuration conf, String columnFamily, String schema) { conf.set(OUTPUT_CQL_SCHEMA_PREFIX + columnFamily, schema); } public static void setTableInsertStatement(Configuration conf, String columnFamily, String insertStatement) { conf.set(OUTPUT_CQL_INSERT_PREFIX + columnFamily, insertStatement); } public static String getTableSchema(Configuration conf, String columnFamily) { String schema = conf.get(OUTPUT_CQL_SCHEMA_PREFIX + columnFamily); if (schema == null) { throw new UnsupportedOperationException("You must set the Table schema using setTableSchema."); } return schema; } public static String getTableInsertStatement(Configuration conf, String columnFamily) { String insert = conf.get(OUTPUT_CQL_INSERT_PREFIX + columnFamily); if (insert == null) { throw new UnsupportedOperationException( "You must set the Table insert statement using setTableSchema."); } return insert; } public static void setDeleteSourceOnSuccess(Configuration conf, boolean deleteSrc) { conf.setBoolean(DELETE_SOURCE, deleteSrc); } public static boolean getDeleteSourceOnSuccess(Configuration conf) { return conf.getBoolean(DELETE_SOURCE, false); } public static void setTableAlias(Configuration conf, String alias, String columnFamily) { conf.set(TABLE_ALIAS_PREFIX + alias, columnFamily); } public static String getTableForAlias(Configuration conf, String alias) { return conf.get(TABLE_ALIAS_PREFIX + alias); } public static class NullOutputCommitter extends OutputCommitter { public void abortTask(TaskAttemptContext taskContext) { } public void cleanupJob(JobContext jobContext) { } public void commitTask(TaskAttemptContext taskContext) { } public boolean needsTaskCommit(TaskAttemptContext taskContext) { return false; } public void setupJob(JobContext jobContext) { } public void setupTask(TaskAttemptContext taskContext) { } } }