E-MapReduce:Use HBase Shell

Create a table

Use create to create a table. Specify the table name and at least one column family.

create 'table1', 'cf1'

Write data

Use put to write a value to a specific cell. Each put call targets one cell, identified by a table name, row key, column, and value.

A column is written as <column-family>:<column-qualifier>. In the example below, cf1:q1 refers to column family cf1 and column qualifier q1. The three put calls write to two rows (r1, r2) across two columns (cf1:q1, cf1:q2).

put 'table1', 'r1', 'cf1:q1', 'v1'
put 'table1', 'r1', 'cf1:q2', 'v2'
put 'table1', 'r2', 'cf1:q1', 'v3'

Scan a table

Use scan to read all rows that match a filter. The example below retrieves all cells in the cf1:q1 column of table1:

scan 'table1', {COLUMNS => 'cf1:q1'}

Expected output:

ROW                                                COLUMN+CELL
 r1                                                column=cf1:q1, timestamp=2022-09-14T16:06:34.339, value=v1
 r2                                                column=cf1:q1, timestamp=2022-09-14T16:06:36.615, value=v3
2 row(s)

Get a single row or cell

Use get to read a single row or a specific cell. The example below retrieves the value of cf1:q1 in row r1:

get 'table1', 'r1', {COLUMNS => 'cf1:q1'}

Expected output:

COLUMN                                             CELL
 cf1:q1                                            timestamp=2022-09-14T16:06:34.339, value=v1
1 row(s)

Delete data

Delete a single cell

Use delete to remove the value of one cell. A cell is the intersection of a row and a column. The example below deletes the cf1:q1 cell in row r2:

delete 'table1', 'r2', 'cf1:q1'

Delete all cells in a row

Use deleteall to remove all column values in a row. Add a column family name to limit the scope to that family. The example below deletes all data in row r1:

deleteall 'table1', 'r1'

Drop a table

Dropping a table requires two steps: disable it first, then drop it.

1. Disable the table:

   disable 'table1'

2. Drop the table:

   drop 'table1'

To bring a disabled table back online without dropping it, run enable:

enable 'table1'