使用

1.从Hive中创建HBase表

• 使用HQL语句创建一个指向HBase的Hive表

CREATE TABLE hbase_table_1(key int, value string) //Hive中的表名hbase_table_1
STORED BY 'org.apache.hadoop.hive.hbase.HBaseStorageHandler'  //指定存储处理器
WITH SERDEPROPERTIES ("hbase.columns.mapping" = ":key,cf1:val") //声明列族，列名
TBLPROPERTIES ("hbase.table.name" = "xyz", "hbase.mapred.output.outputtable" = "xyz");
//hbase.table.name声明HBase表名，为可选属性默认与Hive的表名相同，
//hbase.mapred.output.outputtable指定插入数据时写入的表，如果以后需要往该表插入数据就需要指定该值

• 通过HBase shell可以查看刚刚创建的HBase表的属性

$ hbase shell
HBase Shell; enter 'help<RETURN>' for list of supported commands.
Version: 0.20.3, r902334, Mon Jan 25 13:13:08 PST 2010
hbase(main):001:0> list
xyz
1 row(s) in 0.0530 seconds
hbase(main):002:0> describe "xyz"
DESCRIPTION                                                           ENABLED                               {NAME => 'xyz', FAMILIES => [{NAME => 'cf1', COMPRESSION => 'NONE', VE true                                  RSIONS => '3', TTL => '2147483647', BLOCKSIZE => '65536', IN_MEMORY =>                                       'false', BLOCKCACHE => 'true'}]}
1 row(s) in 0.0220 seconds
hbase(main):003:0> scan "xyz"
ROW                          COLUMN+CELL
0 row(s) in 0.0060 seconds

• 使用HQL向HBase表中插入数据

INSERT OVERWRITE TABLE hbase_table_1 SELECT * FROM pokes WHERE foo=98;

• 在HBase端查看插入的数据

hbase(main):009:0> scan "xyz"
ROW                          COLUMN+CELL                                                                      98                          column=cf1:val, timestamp=1267737987733, value=val_98
1 row(s) in 0.0110 seconds

2.从Hive中映射HBase

• 创建一个指向已经存在的HBase表的Hive表

CREATE EXTERNAL TABLE hbase_table_2(key int, value string)
STORED BY 'org.apache.hadoop.hive.hbase.HBaseStorageHandler'
WITH SERDEPROPERTIES ("hbase.columns.mapping" = "cf1:val")
TBLPROPERTIES("hbase.table.name" = "some_existing_table", "hbase.mapred.output.outputtable" = "some_existing_table");

该Hive表一个外部表，所以删除该表并不会删除HBase表中的数据

注意

3.多列及多列族的映射

如下表：value1和value2来自列族a对应的b c列，value3来自列族d对应的列

CREATE TABLE hbase_table_1(key int, value1 string, value2 int, value3 int)
STORED BY 'org.apache.hadoop.hive.hbase.HBaseStorageHandler'
WITH SERDEPROPERTIES (
"hbase.columns.mapping" = ":key,a:b,a:c,d:e"
);
INSERT OVERWRITE TABLE hbase_table_1 SELECT foo, bar, foo+1, foo+2
FROM pokes WHERE foo=98 OR foo=100;

4.Hive Map类型在HBase中的映射规则

如下表:通过Hive的Map数据类型映射HBase表，这样每行都可以有不同的列组合，列名与map中的key对应，列值与map中的value对应

CREATE TABLE hbase_table_1(value map<string,int>, row_key int)
STORED BY 'org.apache.hadoop.hive.hbase.HBaseStorageHandler'
WITH SERDEPROPERTIES (
"hbase.columns.mapping" = "cf:,:key"
);
INSERT OVERWRITE TABLE hbase_table_1 SELECT map(bar, foo), foo FROM pokes
WHERE foo=98 OR foo=100;

cf为列族，其列名对应map中的bar,列值对应map中的foo

• 在HBase下查看数据

hbase(main):012:0> scan "hbase_table_1"
ROW                          COLUMN+CELL                                                                      100                         column=cf:val_100, timestamp=1267739509194, value=100                            98                          column=cf:val_98, timestamp=1267739509194, value=98
2 row(s) in 0.0080 seconds

• 在Hive下查看数据

hive> select * from hbase_table_1;
Total MapReduce jobs = 1
Launching Job 1 out of 1
...
OK
{"val_100":100}    100
{"val_98":98}    98
Time taken: 3.808 seconds

注意:由于map中的key是作为HBase的列名使用的，所以map中的key类型必须为String类型

以下映射语句都会报错

1.

CREATE TABLE hbase_table_1(key int, value map<int,int>)
STORED BY 'org.apache.hadoop.hive.hbase.HBaseStorageHandler'
WITH SERDEPROPERTIES (
"hbase.columns.mapping" = ":key,cf:"
);

原因：map中的key必须是String

2.

CREATE TABLE hbase_table_1(key int, value string)
STORED BY 'org.apache.hadoop.hive.hbase.HBaseStorageHandler'
WITH SERDEPROPERTIES (
"hbase.columns.mapping" = ":key,cf:"
);

原因：当hbase.columns.mapping中的列族后面为空时(形如cf:),说明在Hive中其对应的数据类型为map，而这条语句中对应的是String所以报错

5.Hive还支持简单的复合行键

如下：创建一张指向HBase的Hive表，行键有两个字段，字段之间使用~分隔

CREATE EXTERNAL TABLE delimited_example(key struct<f1:string, f2:string>, value string)
ROW FORMAT DELIMITED
COLLECTION ITEMS TERMINATED BY '~'
STORED BY 'org.apache.hadoop.hive.hbase.HBaseStorageHandler'
WITH SERDEPROPERTIES ('hbase.columns.mapping'=':key,f:c1');