Hbasel列出表
使用list命令可列出所有表
hbase(main):001:0 > list
使用Java API列出表
下面給出的是使用Java API程序列出所有HBase中表的列表。
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.MasterNotRunningException;
import org.apache.hadoop.hbase.client.HBaseAdmin;
public class ListTables {
public static void main(String args[])throws MasterNotRunningException, IOException{
// Instantiating a configuration class
Configuration conf = HBaseConfiguration.create();
// Instantiating HBaseAdmin class
HBaseAdmin admin = new HBaseAdmin(conf);
// Getting all the list of tables using HBaseAdmin object
HTableDescriptor[] tableDescriptor =admin.listTables();
// printing all the table names.
for (int i=0; i<tableDescriptor.length;i++ ){
System.out.println(tableDescriptor[i].getNameAsString());
}
}
}
HBase禁用表
hbase禁用表使用 disable命令:
disable '表名'
使用is_disabled命令查看錶是否被禁用,返回true或者false
hbase> is_disabled 'table name'
禁用所有表:disable_all
hbase> disable_all 'r.*' 禁用所有和 r.* 匹配的表
輸出:
hbase(main):002:0> disable_all 'raj.*'
raja
rajani
rajendra
rajesh
raju
Disable the above 5 tables (y/n)?
y
5 tables successfully disabled
禁用表使用Java API
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.MasterNotRunningException;
import org.apache.hadoop.hbase.client.HBaseAdmin;
public class DisableTable{
public static void main(String args[]) throws MasterNotRunningException, IOException{
// Instantiating configuration class
Configuration conf = HBaseConfiguration.create();
// Instantiating HBaseAdmin class
HBaseAdmin admin = new HBaseAdmin(conf);
// Verifying weather the table is disabled
Boolean bool = admin.isTableDisabled("emp");
System.out.println(bool);
// Disabling the table using HBaseAdmin object
if(!bool){
admin.disableTable("emp");
System.out.println("Table disabled");
}
}
}
HBase啓用表
啓用表:enable
hbase(main):005:0> enable 'emp'
0 row(s) in 0.4580 seconds
判斷表是否被啓用:is_enabled
hbase(main):031:0> is_enabled 'emp'
true
0 row(s) in 0.0440 seconds
使用Java API啓用表
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.MasterNotRunningException;
import org.apache.hadoop.hbase.client.HBaseAdmin;
public class EnableTable{
public static void main(String args[]) throws MasterNotRunningException, IOException{
// Instantiating configuration class
Configuration conf = HBaseConfiguration.create();
// Instantiating HBaseAdmin class
HBaseAdmin admin = new HBaseAdmin(conf);
// Verifying weather the table is disabled
Boolean bool = admin.isTableEnabled("emp");
System.out.println(bool);
// Disabling the table using HBaseAdmin object
if(!bool){
admin.enableTable("emp");
System.out.println("Table Enabled");
}
}
}
HBase表描述和修改
hbase(main):002:0> describe 'coupon:coupon_member'
Table coupon:coupon_member is ENABLED
coupon:coupon_member
COLUMN FAMILIES DESCRIPTION
{NAME => 'info', BLOOMFILTER => 'ROW', VERSIONS => '1', IN_MEMORY => 'false', KEEP_DELETED_CELLS => 'FALSE', DATA_BLOCK_ENCODING => 'NONE', TTL => 'FOREVER', COMPRESSION => 'NONE', MIN_VERSIONS => '0', BLOCKCACHE => 'true', BLOCKSIZE => '65536', REPLICATION_SCOPE => '0'
}
1 row(s) in 0.1830 seconds
修改
alter用於更改現有表的命令。使用此命令可以更改列族的單元,設定最大數量和刪除表範圍運算符,並從表中刪除列家族。
更改列族單元格的最大數目
下面給出的語法來改變列家族單元的最大數目。
hbase> alter 't1', NAME => 'f1', VERSIONS => 5
在下面的例子中,單元的最大數目設置爲5。
hbase(main):003:0> alter 'emp', NAME => 'personal data', VERSIONS => 5
Updating all regions with the new schema...
0/1 regions updated.
1/1 regions updated.
Done.
0 row(s) in 2.3050 seconds
表範圍運算符
使用alter,可以設置和刪除表範圍,運算符,如MAX_FILESIZE,READONLY,MEMSTORE_FLUSHSIZE,DEFERRED_LOG_FLUSH等。
設置只讀
下面給出的是語法,是用以設置表爲只讀。
hbase>alter ‘t1’, READONLY(option)
在下面的例子中,我們已經設置表emp爲只讀。
hbase(main):006:0> alter 'emp', READONLY
Updating all regions with the new schema...
0/1 regions updated.
1/1 regions updated.
Done.
0 row(s) in 2.2140 seconds
刪除表範圍運算符
也可以刪除表範圍運算。下面給出的是語法,從emp表中刪除“MAX_FILESIZE”。
hbase> alter 't1', METHOD => 'table_att_unset', NAME => 'MAX_FILESIZE'
刪除列族
使用alter,也可以刪除列族。下面給出的是使用alter刪除列族的語法。
hbase> alter ‘ table name ’, ‘delete’ => ‘ column family ’
下面給出的是一個例子,從“emp”表中刪除列族。
假設在HBase中有一個employee表。它包含以下數據:
hbase(main):006:0> scan 'employee'
ROW COLUMN+CELL
row1 column=personal:city, timestamp=1418193767, value=hyderabad
row1 column=personal:name, timestamp=1418193806767, value=raju
row1 column=professional:designation, timestamp=1418193767, value=manager
row1 column=professional:salary, timestamp=1418193806767, value=50000
1 row(s) in 0.0160 seconds
現在使用alter命令刪除指定的 professional 列族。
hbase(main):007:0> alter 'employee','delete'=>'professional'
Updating all regions with the new schema...
0/1 regions updated.
1/1 regions updated.
Done.
0 row(s) in 2.2380 seconds
現在驗證該表中變更後的數據。觀察列族“professional”也沒有了,因爲前面已經被刪除了。
hbase(main):003:0> scan 'employee'
ROW COLUMN+CELL
row1 column=personal:city, timestamp=14181936767, value=hyderabad
row1 column=personal:name, timestamp=1418193806767, value=raju
1 row(s) in 0.0830 seconds
使用Java API添加一列族
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.HColumnDescriptor;
import org.apache.hadoop.hbase.MasterNotRunningException;
import org.apache.hadoop.hbase.client.HBaseAdmin;
public class AddColoumn{
public static void main(String args[]) throws MasterNotRunningException, IOException{
// Instantiating configuration class.
Configuration conf = HBaseConfiguration.create();
// Instantiating HBaseAdmin class.
HBaseAdmin admin = new HBaseAdmin(conf);
// Instantiating columnDescriptor class
HColumnDescriptor columnDescriptor = new HColumnDescriptor("contactDetails");
// Adding column family
admin.addColumn("employee", columnDescriptor);
System.out.println("coloumn added");
}
}
使用Java API刪除列族
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.MasterNotRunningException;
import org.apache.hadoop.hbase.client.HBaseAdmin;
public class DeleteColoumn{
public static void main(String args[]) throws MasterNotRunningException, IOException{
// Instantiating configuration class.
Configuration conf = HBaseConfiguration.create();
// Instantiating HBaseAdmin class.
HBaseAdmin admin = new HBaseAdmin(conf);
// Deleting a column family
admin.deleteColumn("employee","contactDetails");
System.out.println("coloumn deleted");
}
}