HBase Command Line Tutorial

Introduction

Start the HBase Shell

All subsequent commands in this post assume that you are in the HBase shell, which is started via the command listed below.

hbase shell

You should see output similar to:


12/08/12 12:30:52 WARN conf.Configuration: hadoop.native.lib is deprecated. Instead, use io.native.lib.available
HBase Shell; enter 'help<RETURN>' for list of supported commands.
Type "exit<RETURN>" to leave the HBase Shell
Version 0.92.1-cdh4.0.1, rUnknown, Thu Jun 28 18:13:01 PDT 2012

Create a Table

We will initially create a table named test with one column family named columnfamily1.

Using a long column family name, such as columnfamily1 is a horrible idea in production. Every cell (i.e. every value) in HBase is stored fully qualified. This basically means that long column family names will balloon the amount of disk space required to store your data. In summary, keep your column family names as terse as possible.

create 'table1', 'columnfamily1'

List all Tables

list

You’ll see output similar to:


TABLE
table1 1 row(s) in 0.0370 seconds

Let’s now create a second table so that we can see some of the features of the list command.

create 'test', 'cf1'
list

You will see output similar to:

TABLE
table1
test
2 row(s) in 0.0320 seconds

If we only want to see the test table, or all tables that start with “te”, we can use the following command.

list 'te'

or

list 'te.*'

Manually Insert Data into HBase

If you’re using HBase, then you likely have data sets that are TBs in size. As a result, you’ll never actually insert data manually. However, knowing how to insert data manually could prove useful at times.

To start, I’m going to create a new table named cars. My column family is vi, which is an abbreviation of vehicle information.

The schema that follows below is only for illustration purposes, and should not be used to create a production schema. In production, you should create a Row ID that helps to uniquely identify the row, and that is likely to be used in your queries. Therefore, one possibility would be to shift the Make, Model and Year left and use these items in the Row ID.

create 'cars', 'vi'

Let’s insert 3 column qualifies (make, model, year) and the associated values into the first row (row1).

put 'cars', 'row1', 'vi:make', 'bmw'
put 'cars', 'row1', 'vi:model', '5 series'
put 'cars', 'row1', 'vi:year', '2012'

Now let’s add a second row.

put 'cars', 'row2', 'vi:make', 'mercedes'
put 'cars', 'row2', 'vi:model', 'e class'
put 'cars', 'row2', 'vi:year', '2012'

Scan a Table (i.e. Query a Table)

We’ll start with a basic scan that returns all columns in the cars table.

scan 'cars'

You should see output similar to:

ROW           COLUMN+CELL
 row1          column=vi:make, timestamp=1344817012999, value=bmw
 row1          column=vi:model, timestamp=1344817020843, value=5 series
 row1          column=vi:year, timestamp=1344817033611, value=2012
 row2          column=vi:make, timestamp=1344817104923, value=mercedes
 row2          column=vi:model, timestamp=1344817115463, value=e class
 row2          column=vi:year, timestamp=1344817124547, value=2012
2 row(s) in 0.6900 seconds

Reading the output above you’ll notice that the Row ID is listed under ROW. The COLUMN+CELL field shows the column family after column=, then the column qualifier, a timestamp that is automatically created by HBase, and the value.

Importantly, each row in our results shows an individual row id + column family + column qualifier combination. Therefore, you’ll notice that multiple columns in a row are displayed in multiple rows in our results.

The next scan we’ll run will limit our results to the make column qualifier.

scan 'cars', {COLUMNS => ['vi:make']}

If you have a particularly large result set, you can limit the number of rows returned with the LIMIT option. In this example I arbitrarily limit the results to 1 row to demonstrate how LIMIT works.

scan 'cars', {COLUMNS => ['vi:make'], LIMIT => 1}

To learn more about the scan command enter the following:

help 'scan'

Get One Row

The get command allows you to get one row of data at a time. You can optionally limit the number of columns returned.

We’ll start by getting all columns in row1.

get 'cars', 'row1'

You should see output similar to:


COLUMN                   CELL
 vi:make                 timestamp=1344817012999, value=bmw
 vi:model                timestamp=1344817020843, value=5 series
 vi:year                 timestamp=1344817033611, value=2012
3 row(s) in 0.0150 seconds

When looking at the output above, you should notice how the results under COLUMN show the fully qualified column family:column qualifier, such as vi:make.

To get one specific column include the COLUMN option.

get 'cars', 'row1', {COLUMN => 'vi:model'}

You can also get two or more columns by passing an array of columns.

get 'cars', 'row1', {COLUMN => ['vi:model', 'vi:year']}

To learn more about the get command enter:

help 'get'

Delete a Cell (Value)

delete 'cars', 'row2', 'vi:year'

Let’s check that our delete worked.

get 'cars', 'row2'

You should see output that shows 2 columns.


COLUMN    CELL
vi:make   timestamp=1344817104923, value=mercedes
vi:model   timestamp=1344817115463, value=e class
2 row(s) in 0.0080 seconds

Disable and Delete a Table

disable 'cars'
drop 'cars'
disable 'table1'
drop 'table1'
disable 'test'
drop 'test'

View HBase Command Help

help

Exit the HBase Shell

exit
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8 Comments

  1. Hi akbar,
    I am new to Hbase. Can you tell me if we can have our own timestamp inserted instead of default. If “YES” the how do we do that….
    thanx.

    Reply

    1. HI Aniket,

      Yes, you can customize the timestamp value. Assuming you’re using the CLI version of put, then just specify the timestamp you want as a Long. A similar capability exists with the API.

      put ‘table’, ‘row’, ‘column’, ‘value’, timestamp

      However, you should read up on timestamps in detail as other options exist, such as adding your own time column, and since customizing the timestamp has implications worth considering (and too detailed to discuss in a comment).

      Akbar

      Reply

      1. thanx a lot.
        there is another problem i am facing. I am constantly getting an error about Master not running. (Using hbase-0.94.2). but when I check the log files…there its printed that “Master is running”. what could be the reason?

  2. Hello,

    is there any way of getting Hbase epoch time using the linux shell commands.

    I knew perl has feature to convert normal timestamp to EPOCH time, but the problem is it is converting into system EPOCH time not the needed Hbase EPOCH.

    Reply on this would be appreciated much 🙂

    Regards
    Mohan

    Reply

  3. I would like to make a comment here in which i am 90% sure. When we say “Delete a cell” we practically mean that we don’t delete it rather than setting its contents as non-data (like an empty cell not containing data). Even if wanted to say that it would not be applicable as we delete the content of an entire column and i highlight the CONTENT , NOT THE COLUMN.

    P.S.empty cell i don’t know what we mean, but iam pretty sure that we don’t mean NULL as in hbase there are neither NULL values nor joins.

    Reply

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