Database Reference
In-Depth Information
To create a table, we need to create an instance of
HBaseAdmin
and then ask it to create
the table named
test
with a single column family named
data
. In our example, our
table schema is the default. We could use methods on
HTableDescriptor
and
HColumnDescriptor
to change the table schema. Next, the code asserts the table was
actually created, and throws an exception if it wasn't.
To operate on a table, we will need an instance of
HTable
, which we construct by
passing it our
Configuration
instance and the name of the table. We then create
Put
objects in a loop to insert data into the table. Each
Put
puts a single cell value of
value
n
into a row named
row
n
on the column named
data:
n
, where
n
is from 1 to 3.
The column name is specified in two parts: the column family name, and the column fam-
ily qualifier. The code makes liberal use of HBase's
Bytes
utility class (found in the
org.apache.hadoop.hbase.util
package) to convert identifiers and values to the
byte arrays that HBase requires.
Next, we create a
Get
object to retrieve and print the first row that we added. Then we
use a
Scan
object to scan over the table, printing out what we find.
At the end of the program, we clean up by first disabling the table and then deleting it (re-
call that a table must be disabled before it can be dropped).
