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HBase Cheatsheet

A comprehensive cheat sheet for HBase, covering architecture, data model, key operations, and administration.

HBase Architecture & Data Model

Core Components

HRegionServer

Hosts and manages HRegions; handles read/write requests.

HMaster

Assigns regions to RegionServers, handles schema changes, and performs administrative tasks.

ZooKeeper

Maintains configuration information, naming, and distributed synchronization.

HDFS

Hadoop Distributed File System; stores HBase data persistently.

Data Model

HBase is a distributed, scalable, big data store.

It’s designed to store and retrieve data within large tables. Data is stored as key-value pairs.

  • Table: Contains rows.
  • Row Key: Unique identifier for a row.
  • Column Family: Groups related columns.
  • Column Qualifier: Identifies a column within a column family.
  • Version: Each cell value has a version timestamp.

Key Concepts

Regions

Tables are split into regions. A region contains a subset of rows. Regions are the unit of distribution and scalability.

Store

Each region contains one or more stores. A store contains a MemStore and zero or more StoreFiles (HFiles).

MemStore

In-memory buffer that stores recent writes.

HFile

Sorted key-value pairs stored on HDFS.

Basic HBase Operations (CLI)

Table Management

create 'table_name', 'column_family1', 'column_family2' - Creates a new table.

list - Lists all tables.

describe 'table_name' - Describes the table schema.

disable 'table_name' - Disables a table.

enable 'table_name' - Enables a table.

drop 'table_name' - Drops a table (must be disabled first).

exists 'table_name' - Checks if table exists.

Data Manipulation

put 'table_name', 'row_key', 'column_family:qualifier', 'value' - Inserts or updates a cell value.

get 'table_name', 'row_key' - Retrieves all columns for a given row.

get 'table_name', 'row_key', 'column_family:qualifier' - Retrieves a specific cell.

scan 'table_name' - Scans the entire table.

scan 'table_name', {STARTROW => 'row_key1', STOPROW => 'row_key2'} - Scans a range of rows.

delete 'table_name', 'row_key', 'column_family:qualifier' - Deletes a specific cell.

deleteall 'table_name', 'row_key' - Deletes all cells in a row.

HBase Shell Commands

Namespace Management

create_namespace 'namespace_name' - Creates a namespace.

list_namespace - Lists all namespaces.

describe_namespace 'namespace_name' - Describes a namespace.

alter_namespace 'namespace_name', {METHOD => 'set', 'PROPERTY_NAME' => 'property_value'} - Alters a namespace property.

drop_namespace 'namespace_name' - Drops a namespace.

Advanced Scan Operations

scan 'table_name', {COLUMNS => ['col_family1', 'col_family2:qualifier']} - Scans specific column families or columns.

scan 'table_name', {LIMIT => 10} - Limits the number of rows returned.

scan 'table_name', {REVERSED => true} - Scans in reverse order.

scan 'table_name', {FILTER => "RowFilter(=, 'binary:row_key')"} - Applies a filter to the scan.

scan 'table_name', {VERSIONS => 5} - Retrieves the last 5 versions of each cell.

count 'table_name' - Counts the number of rows in a table.

Configuration

HBase configuration is managed through hbase-site.xml. Key properties include:

  • hbase.rootdir: HDFS directory for HBase data.
  • hbase.zookeeper.quorum: List of ZooKeeper servers.
  • hbase.cluster.distributed: Set to true for distributed mode.

HBase Java API

Connecting to HBase 

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.client.Connection;
import org.apache.hadoop.hbase.client.ConnectionFactory;

Configuration config = HBaseConfiguration.create();
config.set("hbase.zookeeper.quorum", "localhost"); // Replace with your ZooKeeper quorum

try (Connection connection = ConnectionFactory.createConnection(config)) {
    // Use the connection
} catch (Exception e) {
    e.printStackTrace();
}

Basic Operations (Java) 

import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.*;
import org.apache.hadoop.hbase.util.Bytes;

TableName tableName = TableName.valueOf("mytable");

try (Table table = connection.getTable(tableName)) {
    // Put data
    Put put = new Put(Bytes.toBytes("row1"));
    put.addColumn(Bytes.toBytes("cf1"), Bytes.toBytes("qual1"), Bytes.toBytes("value1"));
    table.put(put);

    // Get data
    Get get = new Get(Bytes.toBytes("row1"));
    Result result = table.get(get);
    byte[] value = result.getValue(Bytes.toBytes("cf1"), Bytes.toBytes("qual1"));
    String valueStr = Bytes.toString(value);
    System.out.println("Value: " + valueStr);

    // Scan data
    Scan scan = new Scan();
    try (ResultScanner scanner = table.getScanner(scan)) {
        for (Result row : scanner) {
            // Process each row
        }
    }
} catch (Exception e) {
    e.printStackTrace();
}
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