[[PageOutline]]

= '''''HBase''''' =
== 【簡易安裝手冊】 ==
 * How to download and run HBase? in about 10 Minutes. 
  * 以下有幾個簡單的步驟:(包含了下載.安裝及配置HBase)
    * 首先需要先下載HBase最新且穩定的版本[http://www.apache.org/dyn/closer.cgi/hadoop/hbase/ Download]
    * 接著將下載的檔案移到你想要跑HBase的目錄下,如/home/user/hbase
    * 移動到/home/user/hbase此目錄下
{{{
$ cd /home/user/hbase
}}}
    * 編輯conf/hbase-env.sh檔案,加入以下這行 (需視使用者的JAVA路徑而定)
{{{
$ vi conf/hbase-env.sh
  export JAVA_HOME=/usr/lib/jvm/java-6-sun-1.6.0.03
}}}
    * 啟動hbase
{{{
$ bin/start-hbase.sh
}}}   
    * 可以在預設的logs/目錄下看到不少logs檔案
    * 可以執行以下指令進到HQL指令模式,可以試試看
{{{
$ bin/hbase shell
Hbase Shell, 0.0.2 version.
Copyright (c) 2007 by udanax, licensed to Apache Software Foundation.
Type 'help;' for usage.

hql > help;
Type 'help COMMAND;' to see command-specific usage.
+-------------------------+-------------------------+-------------------------+
| Command                 | Description             | Example                 |
+-------------------------+-------------------------+-------------------------+
| EXIT                    | Exit shell              | EXIT;                   |
+-------------------------+-------------------------+-------------------------+
| ALTER                   | Alter structure of table| ALTER TABLE table_name A|
|                         |                         | DD column_spec | ADD (co|
|                         |                         | lumn_spec, column_spec, |
|                         |                         | ...) | CHANGE column_fam|
|                         |                         | ily column_spec | DROP c|
|                         |                         | olumn_family_name | CHAN|
|                         |                         | GE column_spec;         |
+-------------------------+-------------------------+-------------------------+
| CREATE                  | Create tables           | CREATE TABLE table_name |
|                         |                         | (column_family_name [MAX|
|                         |                         | _VERSIONS=n] [MAX_LENGTH|
|                         |                         | =n] [COMPRESSION=NONE|RE|
|                         |                         | CORD|BLOCK] [IN_MEMORY] |
|                         |                         | [BLOOMFILTER=NONE|BLOOMF|
|                         |                         | ILTER|COUNTING_BLOOMFILT|
|                         |                         | ER|RETOUCHED_BLOOMFILTER|
|                         |                         |  VECTOR_SIZE=n NUM_HASH=|
|                         |                         | n], ...)                |
+-------------------------+-------------------------+-------------------------+
| INSERT                  | Insert values into table| INSERT INTO table_name (|
|                         |                         | column_name, ...) VALUES|
|                         |                         |  ('value', ...) WHERE ro|
|                         |                         | w='row_key' [TIMESTAMP '|
|                         |                         | timestamp'];            |
+-------------------------+-------------------------+-------------------------+
| DROP                    | Drop tables             | DROP TABLE table_name [,|
|                         |                         |  table_name] ...;       |
+-------------------------+-------------------------+-------------------------+
| TRUNCATE                | Truncate table is used t| TRUNCATE TABLE table_nam|
|                         | o clean all data from a | e;                      |
|                         | table                   |                         |
+-------------------------+-------------------------+-------------------------+
| DESCRIBE                | Print table information | [DESCRIBE|DESC] table_na|
|                         |                         | me;                     |
+-------------------------+-------------------------+-------------------------+
| JAR                     | Hadoop RunJar util      | JAR jarFile [mainClass] |
|                         |                         | arguments...;           |
+-------------------------+-------------------------+-------------------------+
| FS                      | Hadoop FsShell; entering| FS [-option] arguments..|
|                         |  a lone 'FS;' will emit | ;                       |
|                         | usage                   |                         |
+-------------------------+-------------------------+-------------------------+
| DELETE                  | Delete table data       | DELETE {column_name, [, |
|                         |                         | column_name] ... | *} FR|
|                         |                         | OM table_name WHERE row=|
|                         |                         | 'row-key';              |
+-------------------------+-------------------------+-------------------------+
| SELECT                  | Select values from table| SELECT {column_name, [, |
|                         |                         | column_name] ... | expr[|
|                         |                         | alias] | * } FROM table_|
|                         |                         | name [WHERE row='row_key|
|                         |                         | ' | STARTING FROM 'row-k|
|                         |                         | ey' [UNTIL 'stop-key']] |
|                         |                         | [NUM_VERSIONS = version_|
|                         |                         | count] [TIMESTAMP 'times|
|                         |                         | tamp'] [LIMIT = row_coun|
|                         |                         | t] [INTO FILE 'file_name|
|                         |                         | '];                     |
+-------------------------+-------------------------+-------------------------+
| SHOW                    | Show information about s| SHOW TABLES [or substitu|
|                         | elected title           | tion variable name];    |
+-------------------------+-------------------------+-------------------------+
| CLEAR                   | Clear the screen        | CLEAR;                  |
+-------------------------+-------------------------+-------------------------+
hql > help;
Type 'help COMMAND;' to see command-specific usage.
+-------------------------+-------------------------+-------------------------+
| Command                 | Description             | Example                 |
+-------------------------+-------------------------+-------------------------+
| EXIT                    | Exit shell              | EXIT;                   |
+-------------------------+-------------------------+-------------------------+
| ALTER                   | Alter structure of table| ALTER TABLE table_name A|
|                         |                         | DD column_spec | ADD (co|
|                         |                         | lumn_spec, column_spec, |
|                         |                         | ...) | CHANGE column_fam|
|                         |                         | ily column_spec | DROP c|
|                         |                         | olumn_family_name | CHAN|
|                         |                         | GE column_spec;         |
+-------------------------+-------------------------+-------------------------+
| CREATE                  | Create tables           | CREATE TABLE table_name |
|                         |                         | (column_family_name [MAX|
|                         |                         | _VERSIONS=n] [MAX_LENGTH|
|                         |                         | =n] [COMPRESSION=NONE|RE|
|                         |                         | CORD|BLOCK] [IN_MEMORY] |
|                         |                         | [BLOOMFILTER=NONE|BLOOMF|
|                         |                         | ILTER|COUNTING_BLOOMFILT|
|                         |                         | ER|RETOUCHED_BLOOMFILTER|
|                         |                         |  VECTOR_SIZE=n NUM_HASH=|
|                         |                         | n], ...)                |
+-------------------------+-------------------------+-------------------------+
| INSERT                  | Insert values into table| INSERT INTO table_name (|
|                         |                         | column_name, ...) VALUES|
|                         |                         |  ('value', ...) WHERE ro|
|                         |                         | w='row_key' [TIMESTAMP '|
|                         |                         | timestamp'];            |
+-------------------------+-------------------------+-------------------------+
| DROP                    | Drop tables             | DROP TABLE table_name [,|
|                         |                         |  table_name] ...;       |
+-------------------------+-------------------------+-------------------------+
| TRUNCATE                | Truncate table is used t| TRUNCATE TABLE table_nam|
|                         | o clean all data from a | e;                      |
|                         | table                   |                         |
+-------------------------+-------------------------+-------------------------+
| DESCRIBE                | Print table information | [DESCRIBE|DESC] table_na|
|                         |                         | me;                     |
+-------------------------+-------------------------+-------------------------+
| JAR                     | Hadoop RunJar util      | JAR jarFile [mainClass] |
|                         |                         | arguments...;           |
+-------------------------+-------------------------+-------------------------+
| FS                      | Hadoop FsShell; entering| FS [-option] arguments..|
|                         |  a lone 'FS;' will emit | ;                       |
|                         | usage                   |                         |
+-------------------------+-------------------------+-------------------------+
| DELETE                  | Delete table data       | DELETE {column_name, [, |
|                         |                         | column_name] ... | *} FR|
|                         |                         | OM table_name WHERE row=|
|                         |                         | 'row-key';              |
+-------------------------+-------------------------+-------------------------+
| SELECT                  | Select values from table| SELECT {column_name, [, |
|                         |                         | column_name] ... | expr[|
|                         |                         | alias] | * } FROM table_|
|                         |                         | name [WHERE row='row_key|
|                         |                         | ' | STARTING FROM 'row-k|
|                         |                         | ey' [UNTIL 'stop-key']] |
|                         |                         | [NUM_VERSIONS = version_|
|                         |                         | count] [TIMESTAMP 'times|
|                         |                         | tamp'] [LIMIT = row_coun|
|                         |                         | t] [INTO FILE 'file_name|
|                         |                         | '];                     |
+-------------------------+-------------------------+-------------------------+
| SHOW                    | Show information about s| SHOW TABLES [or substitu|
|                         | elected title           | tion variable name];    |
+-------------------------+-------------------------+-------------------------+
| CLEAR                   | Clear the screen        | CLEAR;                  |
+-------------------------+-------------------------+-------------------------+
hql > 
}}}
    * 要結束hbase server 可用以下指令,而避免使用kill pid指令來殺掉pid,尤其是恐怖的指令kill -9 pid 
{{{
$ bin/stop-hbase.sh
}}}
      * 解釋: kill -9 是當 kill -15 砍不掉的時候 才用,kill -15 會去幫你注意檔案或裝置讀寫有沒有關起來,kill -9 就不管,直接停掉process (reference from sunny)
    * 注意:如果有要跑一個遠端的HDFS,而希望可以用hbase連接,此時需要編輯conf/hbase-site.xml檔案,如下
{{{
$ vi conf/hbase-site.xml 
<configuration>
  <property>
     <name>hbase.rootdir</name>
     <value>file:///tmp/hbase-${user.home}/hbase</value>
     <value>hdfs://localhost:9000/hbase</value>
     <description>
         The directory shared by region servers.
         Should be fully-qualified to include the filesystem to use.
     </description>
  </property>
</configuration>
}}}
== 【常見問題】 ==
 1. HBase資料庫系統在執行關閉伺服器指令後，再重新啟動時裡面的資料表都會遺失? [[BR]]
   Ans: 在hbase/conf目錄裡有一個預設的組態檔hbase-default.xml，裡面的hbase.rootdir屬性預設值是"file:///tmp/hbase-${user.home}/hbase"， 這表示hbase的檔案系統預設是掛載在使用本機的/tmp目錄底下，如果是沒有特別去備份/tmp目錄，或是把/tmp掛載到ram disc裡的情況下，裡面的資料庫資料會在重新啟動作業系統後被作業系統自動清空，因此，只要把hbase.rootdir指定到其他可以永續存放的磁碟空間，就可以解決資料表存放的問題。hbase.rootdir可以直接設定在hbase-default.xml裡或是hbase-site.xml，hbase系統讀取設定檔的優先權順序是hbase-site.xml高於hbase-default.xml，如果想保留原本的預設值，一般是建議直接放到hbase-site.xml就可以了。屬性內容如下：
{{{
value可以自由設定路徑，description非必填，name則是固定的屬性名稱
<property>
    <name>hbase.rootdir</name>
    <value>file:///${user.home}/hbase/dbstored</value>
     <description>The directory shared by region servers.
      Should be fully-qualified to include the filesystem to use.
     </description>
  </property>
}}}

== 【研究團隊】 ==
 * 此網頁內容為國網中心雲端技術研究小組之雲端資料庫(Cloud DB)研究人員之共同研究心得分享，內容如有疏誤請多包含。
 * 技術顧問: 王耀聰
 * 研究人員: 陳惠珊,陳威宇,王心怡
 * 編輯人員: 陳惠珊,王心怡