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* 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.
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package org.apache.accumulo.examples.simple.client;
import java.util.Map.Entry;
import org.apache.accumulo.core.cli.BatchWriterOpts;
import org.apache.accumulo.core.cli.ClientOpts;
import org.apache.accumulo.core.cli.ScannerOpts;
import org.apache.accumulo.core.client.AccumuloException;
import org.apache.accumulo.core.client.AccumuloSecurityException;
import org.apache.accumulo.core.client.BatchWriter;
import org.apache.accumulo.core.client.Connector;
import org.apache.accumulo.core.client.MutationsRejectedException;
import org.apache.accumulo.core.client.Scanner;
import org.apache.accumulo.core.client.TableExistsException;
import org.apache.accumulo.core.client.TableNotFoundException;
import org.apache.accumulo.core.data.Key;
import org.apache.accumulo.core.data.Mutation;
import org.apache.accumulo.core.data.Range;
import org.apache.accumulo.core.data.Value;
import org.apache.accumulo.core.security.Authorizations;
import org.apache.hadoop.io.Text;
import org.apache.log4j.Logger;
/**
* A demonstration of reading entire rows and deleting entire rows.
*/
public class RowOperations {
private static final Logger log = Logger.getLogger(RowOperations.class);
private static Connector connector;
private static String table = "example";
private static BatchWriter bw;
public static void main(String[] args) throws AccumuloException, AccumuloSecurityException, TableExistsException, TableNotFoundException,
MutationsRejectedException {
ClientOpts opts = new ClientOpts();
ScannerOpts scanOpts = new ScannerOpts();
BatchWriterOpts bwOpts = new BatchWriterOpts();
opts.parseArgs(RowOperations.class.getName(), args, scanOpts, bwOpts);
// First the setup work
connector = opts.getConnector();
// lets create an example table
connector.tableOperations().create(table);
// lets create 3 rows of information
Text row1 = new Text("row1");
Text row2 = new Text("row2");
Text row3 = new Text("row3");
// Which means 3 different mutations
Mutation mut1 = new Mutation(row1);
Mutation mut2 = new Mutation(row2);
Mutation mut3 = new Mutation(row3);
// And we'll put 4 columns in each row
Text col1 = new Text("1");
Text col2 = new Text("2");
Text col3 = new Text("3");
Text col4 = new Text("4");
// Now we'll add them to the mutations
mut1.put(new Text("column"), col1, System.currentTimeMillis(), new Value("This is the value for this key".getBytes()));
mut1.put(new Text("column"), col2, System.currentTimeMillis(), new Value("This is the value for this key".getBytes()));
mut1.put(new Text("column"), col3, System.currentTimeMillis(), new Value("This is the value for this key".getBytes()));
mut1.put(new Text("column"), col4, System.currentTimeMillis(), new Value("This is the value for this key".getBytes()));
mut2.put(new Text("column"), col1, System.currentTimeMillis(), new Value("This is the value for this key".getBytes()));
mut2.put(new Text("column"), col2, System.currentTimeMillis(), new Value("This is the value for this key".getBytes()));
mut2.put(new Text("column"), col3, System.currentTimeMillis(), new Value("This is the value for this key".getBytes()));
mut2.put(new Text("column"), col4, System.currentTimeMillis(), new Value("This is the value for this key".getBytes()));
mut3.put(new Text("column"), col1, System.currentTimeMillis(), new Value("This is the value for this key".getBytes()));
mut3.put(new Text("column"), col2, System.currentTimeMillis(), new Value("This is the value for this key".getBytes()));
mut3.put(new Text("column"), col3, System.currentTimeMillis(), new Value("This is the value for this key".getBytes()));
mut3.put(new Text("column"), col4, System.currentTimeMillis(), new Value("This is the value for this key".getBytes()));
// Now we'll make a Batch Writer
bw = connector.createBatchWriter(table, bwOpts.getBatchWriterConfig());
// And add the mutations
bw.addMutation(mut1);
bw.addMutation(mut2);
bw.addMutation(mut3);
// Force a send
bw.flush();
// Now lets look at the rows
Scanner rowThree = getRow(scanOpts, new Text("row3"));
Scanner rowTwo = getRow(scanOpts, new Text("row2"));
Scanner rowOne = getRow(scanOpts, new Text("row1"));
// And print them
log.info("This is everything");
printRow(rowOne);
printRow(rowTwo);
printRow(rowThree);
System.out.flush();
// Now lets delete rowTwo with the iterator
rowTwo = getRow(scanOpts, new Text("row2"));
deleteRow(rowTwo);
// Now lets look at the rows again
rowThree = getRow(scanOpts, new Text("row3"));
rowTwo = getRow(scanOpts, new Text("row2"));
rowOne = getRow(scanOpts, new Text("row1"));
// And print them
log.info("This is row1 and row3");
printRow(rowOne);
printRow(rowTwo);
printRow(rowThree);
System.out.flush();
// Should only see the two rows
// Now lets delete rowOne without passing in the iterator
deleteRow(scanOpts, row1);
// Now lets look at the rows one last time
rowThree = getRow(scanOpts, new Text("row3"));
rowTwo = getRow(scanOpts, new Text("row2"));
rowOne = getRow(scanOpts, new Text("row1"));
// And print them
log.info("This is just row3");
printRow(rowOne);
printRow(rowTwo);
printRow(rowThree);
System.out.flush();
// Should only see rowThree
// Always close your batchwriter
bw.close();
// and lets clean up our mess
connector.tableOperations().delete(table);
// fin~
}
/**
* Deletes a row given a text object
*/
private static void deleteRow(ScannerOpts scanOpts, Text row) throws AccumuloException, AccumuloSecurityException, TableNotFoundException {
deleteRow(getRow(scanOpts, row));
}
/**
* Deletes a row, given a Scanner of JUST that row
*/
private static void deleteRow(Scanner scanner) throws MutationsRejectedException {
Mutation deleter = null;
// iterate through the keys
for (Entry<Key,Value> entry : scanner) {
// create a mutation for the row
if (deleter == null)
deleter = new Mutation(entry.getKey().getRow());
// the remove function adds the key with the delete flag set to true
deleter.putDelete(entry.getKey().getColumnFamily(), entry.getKey().getColumnQualifier());
}
bw.addMutation(deleter);
bw.flush();
}
/**
* Just a generic print function given an iterator. Not necessarily just for printing a single row
*/
private static void printRow(Scanner scanner) {
// iterates through and prints
for (Entry<Key,Value> entry : scanner)
log.info("Key: " + entry.getKey().toString() + " Value: " + entry.getValue().toString());
}
/**
* Gets a scanner over one row
*/
private static Scanner getRow(ScannerOpts scanOpts, Text row) throws AccumuloException, AccumuloSecurityException, TableNotFoundException {
// Create a scanner
Scanner scanner = connector.createScanner(table, Authorizations.EMPTY);
scanner.setBatchSize(scanOpts.scanBatchSize);
// Say start key is the one with key of row
// and end key is the one that immediately follows the row
scanner.setRange(new Range(row));
return scanner;
}
}