HBase入门HBase入门
部分内容参考于http://www.nabble.com/Re%3A-Map-Reduce-over-HBase---sample-code-p18253120.html
HBase是Hadoop的一个子项目,HBase采用了Google BigTable的稀疏的,面向列的数据库实现方式的理论,建立在hadoop的hdfs上,一方面里用了hdfs的高可靠性和可伸缩行,另外一方面里用了BigTable的高效数据组织形式.可以说HBase为海量数据的real-time相应提供了很好的一个开源解决方案.据说在某运营商中使用类似于BigTable(个人猜测应该就是HBase)的技术可以在两秒时间内从2TB数据中查找到某条话费记录.而这是原来该运营商使用Oracle数据库所无法解决的问题.
对于HBase使用的类似与BigTable的技术我们这里就不仔细描述,可以参考google的论文以及网上的一些相关资料.另外,HBase的配置在HBase的官方文档中有很详细的描述.可以参见相关文档.
HBase提供了一个类似于mysql等关系型数据库的shell.通过该shell我们可以对HBase的内的相关表以及列族进行控制和处理.HBase shell的help命令比较详细的列出了HBase所支持的命令.具体使用方法可以参见其文档.
这里我们用一个学生成绩表作为例子,对HBase的基本操作和基本概念进行讲解:
下面是学生的成绩表:
name grad course:math course:art
Tom 1 87 97
Jerry 2 100 80
这里grad对于表来说是一个列,course对于表来说是一个列族,这个列族由两个列组成:math和art,当然我们可以根据我们的需要在course中建立更多的列族,如computer,physics等相应的列添加入course列族.
有了上面的想法和需求,我们就可以在HBase中建立相应的数据表啦!
1, 建立一个表格 scores 具有两个列族grad 和courese
hbase(main):002:0> create 'scores', 'grade', 'course'
0 row(s) in 4.1610 seconds
2,查看当先HBase中具有哪些表
hbase(main):003:0> list
scores
1 row(s) in 0.0210 seconds
3,查看表的构造
hbase(main):004:0> describe 'scores'
{NAME => 'scores', IS_ROOT => 'false', IS_META => 'false', FAMILIES => [{NAME => 'course', BLOOMFILTER => 'false', IN_MEMORY => 'false', LENGTH => '2147483647', BLOCKCACHE => 'false', VERSIONS => '3', TTL => '-1', COMPRESSION => 'NONE'}, {NAME => 'grade', BLOOMFILTER => 'false', IN_MEMORY => 'false', LENGTH => '2147483647', BLOCKCACHE => 'false', VERSIONS => '3', TTL => '-1', COMPRESSION => 'NONE'}]}
1 row(s) in 0.0130 seconds
4, 加入一行数据,行名称为 Tom 列族grad的列名为”” 值位1
hbase(main):005:0> put 'scores', 'Tom', 'grade:', '1'
0 row(s) in 0.0070 seconds
5,给Tom这一行的数据的列族添加一列 <math,87>
hbase(main):006:0> put 'scores', 'Tom', 'course:math', '87'
0 row(s) in 0.0040 seconds
6,给Tom这一行的数据的列族添加一列 <art,97>
hbase(main):007:0> put 'scores', 'Tom', 'course:art', '97'
0 row(s) in 0.0030 seconds
7, 加入一行数据,行名称为 Jerry 列族grad的列名为”” 值位2
hbase(main):008:0> put 'scores', 'Jerry', 'grade:', '2'
0 row(s) in 0.0040 seconds
8,给Jerry这一行的数据的列族添加一列 <math,100>
hbase(main):009:0> put 'scores', 'Jerry', 'course:math', '100'
0 row(s) in 0.0030 seconds
9,给Jerry这一行的数据的列族添加一列 <art,80>
hbase(main):010:0> put 'scores', 'Jerry', 'course:art', '80'
0 row(s) in 0.0050 seconds
10,查看scores表中Tom的相关数据
hbase(main):011:0> get 'scores', 'Tom'
COLUMN CELL
course:art timestamp=1224726394286, value=97
course:math timestamp=1224726377027, value=87
grade: timestamp=1224726360727, value=1
3 row(s) in 0.0070 seconds
11,查看scores表中所有数据
hbase(main):012:0> scan 'scores'
ROW COLUMN+CELL
Tom column=course:art, timestamp=1224726394286, value=97
Tom column=course:math, timestamp=1224726377027, value=87
Tom column=grade:, timestamp=1224726360727, value=1
Jerry column=course:art, timestamp=1224726424967, value=80
Jerry column=course:math, timestamp=1224726416145, value=100
Jerry column=grade:, timestamp=1224726404965, value=2
6 row(s) in 0.0410 seconds
12,查看scores表中所有数据courses列族的所有数据
hbase(main):013:0> scan 'scores', ['course:']
ROW COLUMN+CELL
Tom column=course:art, timestamp=1224726394286, value=97
Tom column=course:math, timestamp=1224726377027, value=87
Jerry column=course:art, timestamp=1224726424967, value=80
Jerry column=course:math, timestamp=1224726416145, value=100
4 row(s) in 0.0200 seconds
上面就是HBase的基本shell操作的一个例子,可以看出,hbase的shell还是比较简单易用的,从中也可以看出HBase shell缺少很多传统sql中的一些类似于like等相关操作,当然,HBase作为BigTable的一个开源实现,而BigTable是作为google业务的支持模型,很多sql语句中的一些东西可能还真的不需要.
当然,通过程序我们也可以对HBase进行相关的操作.下面的程序就完成了上面shell操作的内容:
Java代码
- import java.io.IOException;
- import java.io.ByteArrayOutputStream;
- import java.io.DataOutputStream;
- import java.io.ByteArrayInputStream;
- import java.io.DataInputStream;
- import java.util.Map;
- import org.apache.hadoop.io.Writable;
- import org.apache.hadoop.io.IntWritable;
- import org.apache.hadoop.hbase.HBaseConfiguration;
- import org.apache.hadoop.hbase.HTableDescriptor;
- import org.apache.hadoop.hbase.HColumnDescriptor;
- import org.apache.hadoop.hbase.client.HBaseAdmin;
- import org.apache.hadoop.hbase.client.HTable;
- import org.apache.hadoop.hbase.io.BatchUpdate;
- import org.apache.hadoop.hbase.io.RowResult;
- import org.apache.hadoop.hbase.io.Cell;
- import org.apache.hadoop.hbase.util.Writables;
-
- public class HBaseBasic {
-
- public static void main(String[] args) throws Exception {
-
- HBaseConfiguration config = new HBaseConfiguration();
-
- HBaseAdmin admin = new HBaseAdmin(config);
-
-
- if (admin.tableExists("scores")) {
-
- System.out.println("drop table");
-
- admin.disableTable("scores");
-
- admin.deleteTable("scores");
-
- }
-
- System.out.println("create table");
-
- HTableDescriptor tableDescripter = new HTableDescriptor("scores".getBytes());
-
- tableDescripter.addFamily(new HColumnDescriptor("grade:"));
-
- tableDescripter.addFamily(new HColumnDescriptor("course:"));
-
- admin.createTable(tableDescripter);
-
-
- HTable table = new HTable(config, "scores");
-
- System.out.println("add Tom's data");
-
- BatchUpdate tomUpdate = new BatchUpdate("Tom");
-
- tomUpdate.put("grade:", Writables.getBytes(new IntWritable(1)));
-
- tomUpdate.put("course:math", Writables.getBytes(new IntWritable(87)));
-
- tomUpdate.put("course:art", Writables.getBytes(new IntWritable(97)));
-
- table.commit(tomUpdate);
-
- System.out.println("add Jerry's data");
-
- BatchUpdate jerryUpdate = new BatchUpdate("Jerry");
-
- jerryUpdate.put("grade:", Writables.getBytes(new IntWritable(2)));
-
- jerryUpdate.put("course:math", Writables.getBytes(new IntWritable(100)));
-
- jerryUpdate.put("course:art", Writables.getBytes(new IntWritable(80)));
-
- table.commit(jerryUpdate);
-
- for (RowResult row : table.getScanner(new String[] { "course:" })) {
-
- System.out.format("ROW\t%s\n", new String(row.getRow()));
-
- for (Map.Entry<byte[], Cell> entry : row.entrySet()) {
-
- String column = new String(entry.getKey());
-
- Cell cell = entry.getValue();
-
- IntWritable value = new IntWritable();
-
- Writables.copyWritable(cell.getValue(), value);
-
- System.out.format(" COLUMN\t%s\t%d\n", column, value.get());
-
- }
- }
- }
- }
import java.io.IOException;import java.io.ByteArrayOutputStream;import java.io.DataOutputStream;import java.io.ByteArrayInputStream;import java.io.DataInputStream;import java.util.Map;import org.apache.hadoop.io.Writable;import org.apache.hadoop.io.IntWritable;import org.apache.hadoop.hbase.HBaseConfiguration;import org.apache.hadoop.hbase.HTableDescriptor;import org.apache.hadoop.hbase.HColumnDescriptor;import org.apache.hadoop.hbase.client.HBaseAdmin;import org.apache.hadoop.hbase.client.HTable;import org.apache.hadoop.hbase.io.BatchUpdate;import org.apache.hadoop.hbase.io.RowResult;import org.apache.hadoop.hbase.io.Cell;import org.apache.hadoop.hbase.util.Writables;public class HBaseBasic { public static void main(String[] args) throws Exception { HBaseConfiguration config = new HBaseConfiguration(); HBaseAdmin admin = new HBaseAdmin(config); if (admin.tableExists("scores")) { System.out.println("drop table"); admin.disableTable("scores"); admin.deleteTable("scores"); } System.out.println("create table"); HTableDescriptor tableDescripter = new HTableDescriptor("scores".getBytes()); tableDescripter.addFamily(new HColumnDescriptor("grade:")); tableDescripter.addFamily(new HColumnDescriptor("course:")); admin.createTable(tableDescripter); HTable table = new HTable(config, "scores"); System.out.println("add Tom's data"); BatchUpdate tomUpdate = new BatchUpdate("Tom"); tomUpdate.put("grade:", Writables.getBytes(new IntWritable(1))); tomUpdate.put("course:math", Writables.getBytes(new IntWritable(87))); tomUpdate.put("course:art", Writables.getBytes(new IntWritable(97))); table.commit(tomUpdate); System.out.println("add Jerry's data"); BatchUpdate jerryUpdate = new BatchUpdate("Jerry"); jerryUpdate.put("grade:", Writables.getBytes(new IntWritable(2))); jerryUpdate.put("course:math", Writables.getBytes(new IntWritable(100))); jerryUpdate.put("course:art", Writables.getBytes(new IntWritable(80))); table.commit(jerryUpdate); for (RowResult row : table.getScanner(new String[] { "course:" })) { System.out.format("ROW\t%s\n", new String(row.getRow())); for (Map.Entry<byte[], Cell> entry : row.entrySet()) { String column = new String(entry.getKey()); Cell cell = entry.getValue(); IntWritable value = new IntWritable(); Writables.copyWritable(cell.getValue(), value); System.out.format(" COLUMN\t%s\t%d\n", column, value.get()); } } }}
输出如下:
drop table
09/07/11 08:51:59 INFO client.HBaseAdmin: Disabled scores
09/07/11 08:51:59 INFO client.HBaseAdmin: Deleted scores
create table
add Tom's data
add Jerry's data
ROW Tom
COLUMN course:art 97
COLUMN course:math 87
ROW Jerry
COLUMN course:art 80
COLUMN course:math 100
转载于:http://labs.chinamobile.com/mblog/4110_22332