### Start ServerKillingMonkeyFactory

Source: https://github.com/apache/hbase/blob/master/hbase-website/app/pages/_docs/docs/_mdx/(multi-page)/building-and-developing/tests.mdx

Example command to start ChaosMonkey with ServerKillingMonkeyFactory, which includes actions like rolling restarts of RegionServers and Masters.

```bash
$ bin/hbase org.apache.hadoop.hbase.chaos.util.ChaosMonkeyRunner -m org.apache.hadoop.hbase.chaos.factories.ServerKillingMonkeyFactory
```

--------------------------------

### HBase Setup and ZooKeeper Startup Commands

Source: https://github.com/apache/hbase/blob/master/hbase-website/app/pages/_docs/docs/_mdx/(multi-page)/zookeeper.mdx

Commands to clone the HBase repository, run tests, and start ZooKeeper, master, and regionserver processes for initial configuration.

```bash
git clone https://gitbox.apache.org/repos/asf/hbase.git
cd hbase
mvn clean test -Dtest=TestZooKeeperACL
```

```bash
bin/hbase zookeeper &
bin/hbase master &
bin/hbase regionserver &
```

--------------------------------

### Starting HBase Cluster Components

Source: https://github.com/apache/hbase/blob/master/hbase-website/app/pages/_docs/docs/_mdx/(multi-page)/zookeeper.mdx

Commands to start the ZooKeeper, Master, and RegionServer components of an HBase cluster. These commands should be executed on the appropriate hosts as per your cluster setup.

```bash
bin/hbase zookeeper start
```

```bash
bin/hbase master start
```

```bash
bin/hbase regionserver start
```

--------------------------------

### Setting up Symlinks for Native Libraries

Source: https://github.com/apache/hbase/blob/master/hbase-website/app/pages/_docs/docs/_mdx/(multi-page)/compression.mdx

This example demonstrates how to create symbolic links to Hadoop's native libraries within the HBase directory structure. This is a common method to make them discoverable by HBase, especially when Hadoop and HBase installations are in adjacent locations.

```bash
$ mkdir -p ~/hbaseLinux-amd64-64 -> /home/stack/hadoop/lib/native/lib/native/
$ cd ~/hbase/lib/native/
$ ln -s ~/hadoop/lib/native Linux-amd64-64
$ ls -la
```

--------------------------------

### Starting HBase Cluster Components

Source: https://github.com/apache/hbase/blob/master/hbase-website/public/book.html

Commands to start HBase cluster services. Ensure Kerberos is properly configured before starting.

```bash
bin/hbase zookeeper start
    bin/hbase master start
    bin/hbase regionserver start
```

--------------------------------

### Minor Compaction File Selection - Example 2

Source: https://github.com/apache/hbase/blob/master/hbase-website/app/pages/_docs/docs/_mdx/(multi-page)/architecture/regions.mdx

Illustrates a scenario where no compaction is initiated due to insufficient files meeting the minimum threshold. This example uses the same parameters as Example 1 but with different file sizes.

```text
- hbase.hstore.compaction.ratio = 1.0f
- hbase.hstore.compaction.min = 3 (files)
- hbase.hstore.compaction.max = 5 (files)
- hbase.hstore.compaction.min.size = 10 (bytes)
- hbase.hstore.compaction.max.size = 1000 (bytes)

The following StoreFiles exist: 100, 25, 12, and 12 bytes apiece (oldest to newest). With the above parameters, no compaction will be started.

Why?

- 100 → No, because sum(25, 12, 12) * 1.0 = 47
- 25 → No, because sum(12, 12) * 1.0 = 24
- 12 → No. Candidate because sum(12) * 1.0 = 12, there are only 2 files to compact and that is less than the threshold of 3
- 12 → No. Candidate because the previous StoreFile was, but there are not enough files to compact
```

--------------------------------

### Install Dependencies

Source: https://github.com/apache/hbase/blob/master/dev-support/git-jira-release-audit/README.md

Install project dependencies from the requirements.txt file into the active virtual environment.

```shell
$ ./venv/bin/pip install -r ./requirements.txt
...
Successfully installed...
```

--------------------------------

### Start HBase Services

Source: https://github.com/apache/hbase/blob/master/hbase-website/app/pages/_docs/docs/_mdx/(multi-page)/configuration/confirm.mdx

Run this command from the HBASE_HOME directory to start the HBase services. Ensure HDFS and ZooKeeper are running beforehand, or HBase will start them for you.

```bash
bin/start-hbase.sh
```

--------------------------------

### Start a New Regionserver

Source: https://github.com/apache/hbase/blob/master/hbase-website/app/pages/_docs/docs/_mdx/(multi-page)/operational-management/node.mdx

Starts a new regionserver process. The new regionserver will register itself with the master. It is recommended to also start a DataNode on the same machine for local file access.

```bash
$ ./bin/hbase-daemon.sh start regionserver
```

--------------------------------

### Install HBase JARs Locally

Source: https://github.com/apache/hbase/blob/master/hbase-website/app/pages/_docs/docs/_mdx/(multi-page)/building-and-developing/building.mdx

The 'install' target compiles HBase and installs the resulting JARs into your local Maven repository (~/.m2/).

```bash
mvn install
```

--------------------------------

### HBase Website Download Link Example

Source: https://github.com/apache/hbase/blob/master/hbase-website/public/book.html

Example of a link to download HBase releases from the official website.

```text
https://hbase.apache.org/downloads
```

--------------------------------

### Starting HBase Cluster

Source: https://github.com/apache/hbase/blob/master/hbase-website/app/pages/_docs/docs/_mdx/(multi-page)/zookeeper.mdx

Commands to start HBase master and regionserver processes.

```bash
bin/hbase master start
bin/hbase regionserver start
```

--------------------------------

### Install Docker CE

Source: https://github.com/apache/hbase/blob/master/dev-support/create-release/README.txt

Install Docker Community Edition (CE), the command-line interface (CLI), and containerd.io on your system.

```bash
sudo apt-get update
sudo apt-get install -y docker-ce docker-ce-cli containerd.io
```

--------------------------------

### HBase Cluster Startup Output Example

Source: https://github.com/apache/hbase/blob/master/hbase-website/public/book.html

Example output demonstrating the sequence of service startups when 'start-hbase.sh' is executed. It shows ZooKeeper, master, and regionserver initialization on different nodes.

```text
node-c.example.com: starting zookeeper, logging to /home/hbuser/hbase-0.98.3-hadoop2/bin/../logs/hbase-hbuser-zookeeper-node-c.example.com.out
node-a.example.com: starting zookeeper, logging to /home/hbuser/hbase-0.98.3-hadoop2/bin/../logs/hbase-hbuser-zookeeper-node-a.example.com.out
node-b.example.com: starting zookeeper, logging to /home/hbuser/hbase-0.98.3-hadoop2/bin/../logs/hbase-hbuser-zookeeper-node-b.example.com.out
starting master, logging to /home/hbuser/hbase-0.98.3-hadoop2/bin/../logs/hbase-hbuser-master-node-a.example.com.out
node-c.example.com: starting regionserver, logging to /home/hbuser/hbase-0.98.3-hadoop2/bin/../logs/hbase-hbuser-regionserver-node-c.example.com.out
node-b.example.com: starting regionserver, logging to /home/hbuser/hbase-0.98.3-hadoop2/bin/../logs/hbase-hbuser-regionserver-node-b.example.com.out
node-b.example.com: starting master, logging to /home/hbuser/hbase-0.98.3-hadoop2/bin/../logs/hbase-hbuser-master-nodeb.example.com.out
```

--------------------------------

### BulkPut Example with DStreams in Scala

Source: https://github.com/apache/hbase/blob/master/hbase-website/public/book.html

Shows a basic setup for using bulkPut with Spark Streaming DStreams in Scala. This example requires an existing SparkContext and HBaseConfiguration.

```scala
val sc = new SparkContext("local", "test")
val config = new HBaseConfiguration()

```

--------------------------------

### Test Docker Installation

Source: https://github.com/apache/hbase/blob/master/dev-support/create-release/README.txt

Run the 'hello-world' Docker image to verify that Docker is installed and functioning correctly. This is a standard post-installation test.

```bash
docker run hello-world
```

--------------------------------

### HBase Table Region Boundaries Example

Source: https://github.com/apache/hbase/blob/master/hbase-website/app/pages/_docs/docs/_mdx/(multi-page)/bulk-data-generator-tool.mdx

Illustrates the start and end keys for regions in a pre-split HBase table. This example shows a table with 10 split-count, resulting in 11 regions.

```text
(-000001, 000001-000002, 000002-000003, ...., 000009-000010, 0000010-)
```

--------------------------------

### Example: Create Full Backup with Specific Tables

Source: https://github.com/apache/hbase/blob/master/hbase-website/app/pages/_docs/docs/_mdx/(multi-page)/backup-restore/commands.mdx

This example demonstrates creating a full backup for specific tables (SALES2, SALES3) to an HDFS path, utilizing three parallel workers for the operation.

```bash
$ hbase backup create full hdfs://host5:9000/data/backup -t SALES2,SALES3 -w 3
```

--------------------------------

### HBase MapReduce Mapper Accessing Other Tables Example

Source: https://github.com/apache/hbase/blob/master/hbase-website/public/book.html

Example of a Mapper that accesses another HBase table for lookups. An HBase Table instance is created in the setup method using a Connection.

```Java
public class MyMapper extends TableMapper<Text, LongWritable> {
  private Table myOtherTable;

  public void setup(Context context) {
    // In here create a Connection to the cluster and save it or use the Connection
    // from the existing table
    myOtherTable = connection.getTable("myOtherTable");
  }

  public void map(ImmutableBytesWritable row, Result value, Context context) throws IOException, InterruptedException {
    // process Result...
    // use 'myOtherTable' for lookups
  }

}
```

--------------------------------

### Initiate Release Build

Source: https://github.com/apache/hbase/blob/master/dev-support/release-vm/README.md

Start the release build process within the Guest VM using the provided script. Ensure you have created the necessary build directory beforehand.

```shell
guest:~$ mkdir ~/build-2.3.1-rc0
guest:~$ cd repos/hbase
guest:~/repos/hbase$ ./dev-support/create-release/do-release-docker.sh -d ~/build-2.3.1-rc0/ ...
```

--------------------------------

### Check Python Version

Source: https://github.com/apache/hbase/blob/master/dev-support/git-jira-release-audit/README.md

Verify that Python 3.7.6 or a compatible version is installed before proceeding with setup.

```shell
$ python3 --version
Python 3.7.6
```

--------------------------------

### Import and Verify GPG in Guest

Source: https://github.com/apache/hbase/blob/master/dev-support/release-vm/README.md

Import your public GPG key into the Guest VM and verify GPG agent passthrough by signing and verifying a file. Always use '--no-autostart' for GPG commands in the Guest.

```shell
guest:~$ gpg --no-autostart --import /vagrant/gpg.<you>.apache.pub
...
gpg: Total number processed: 1
gpg:
               imported: 1
guest:~$ gpg --no-autostart --detach --armor --sign repos/hbase/pom.xml
guest:~$ gpg --no-autostart --verify repos/hbase/pom.xml.asc
gpg: assuming signed data in 'repos/hbase/pom.xml'
...
guest:~$ rm repos/hbase/pom.xml.asc
```

--------------------------------

### Example HBase:slowlog Scan Result Rows

Source: https://github.com/apache/hbase/blob/master/hbase-website/app/pages/_docs/docs/_mdx/(multi-page)/operational-management/metrics-and-monitoring.mdx

This example shows the structure of data stored in the hbase:slowlog system table, including details like call details, client address, method name, and start time.

```text
 \x024\xC1\x03\xE9\x04\xF5@                                  column=info:call_details, timestamp=2020-05-16T14:58:14.211Z, value=Scan(org.apache.hadoop.hbase.shaded.protobuf.generated.ClientProtos$ScanRequest)
 \x024\xC1\x03\xE9\x04\xF5@                                  column=info:client_address, timestamp=2020-05-16T14:58:14.211Z, value=172.20.10.2:57347
 \x024\xC1\x03\xE9\x04\xF5@                                  column=info:method_name, timestamp=2020-05-16T14:58:14.211Z, value=Scan
 \x024\xC1\x03\xE9\x04\xF5@                                  column=info:param, timestamp=2020-05-16T14:58:14.211Z, value=region { type: REGION_NAME value: "hbase:meta,,1" } scan { column { family: "info" } attribute { name: "_isolationle
                                                              value: "\x5C000" } start_row: "cluster_test,33333333,99999999999999" stop_row: "cluster_test,," time_range { from: 0 to: 9223372036854775807 } max_versions: 1 cache_blocks
                                                              true max_result_size: 2097152 reversed: true caching: 10 include_stop_row: true readType: PREAD } number_of_rows: 10 close_scanner: false client_handles_partials: true client_
                                                              handles_heartbeats: true track_scan_metrics: false
 \x024\xC1\x03\xE9\x04\xF5@                                  column=info:processing_time, timestamp=2020-05-16T14:58:14.211Z, value=18
 \x024\xC1\x03\xE9\x04\xF5@                                  column=info:queue_time, timestamp=2020-05-16T14:58:14.211Z, value=0
 \x024\xC1\x03\xE9\x04\xF5@                                  column=info:region_name, timestamp=2020-05-16T14:58:14.211Z, value=hbase:meta,,1
 \x024\xC1\x03\xE9\x04\xF5@                                  column=info:response_size, timestamp=2020-05-16T14:58:14.211Z, value=1575
 \x024\xC1\x03\xE9\x04\xF5@                                  column=info:server_class, timestamp=2020-05-16T14:58:14.211Z, value=HRegionServer
 \x024\xC1\x03\xE9\x04\xF5@                                  column=info:start_time, timestamp=2020-05-16T14:58:14.211Z, value=1589640743732
 \x024\xC1\x03\xE9\x04\xF5@                                  column=info:type, timestamp=2020-05-16T14:58:14.211Z, value=ALL
 \x024\xC1\x03\xE9\x04\xF5@                                  column=info:username, timestamp=2020-05-16T14:58:14.211Z, value=user2
 \x024\xC1\x06X\x81\xF6\xEC                                  column=info:call_details, timestamp=2020-05-16T14:59:58.764Z, value=Scan(org.apache.hadoop.hbase.shaded.protobuf.generated.ClientProtos$ScanRequest)
```

--------------------------------

### Display Help for Release Build Script

Source: https://github.com/apache/hbase/blob/master/dev-support/create-release/README.txt

Execute this command to view the available options and usage instructions for the release-build.sh script.

```bash
$ release-build.sh --help
```

--------------------------------

### Run ChaosMonkey Runner

Source: https://github.com/apache/hbase/blob/master/hbase-website/app/pages/_docs/docs/_mdx/(multi-page)/building-and-developing/tests.mdx

Start the ChaosMonkey runner from a single host to initiate chaos testing. This example uses the default PeriodicRandomActionPolicy.

```bash
$ bin/hbase org.apache.hadoop.hbase.chaos.util.ChaosMonkeyRunner
```

--------------------------------

### Example WALPlayer Usage

Source: https://github.com/apache/hbase/blob/master/hbase-website/app/pages/_docs/docs/_mdx/(multi-page)/operational-management/tools.mdx

An example demonstrating how to use WALPlayer to replay WAL files from a backup directory, mapping old tables to new ones.

```bash
$ bin/hbase org.apache.hadoop.hbase.mapreduce.WALPlayer /backuplogdir oldTable1,oldTable2 newTable1,newTable2
```

--------------------------------

### CopyTable Example with Specific Options

Source: https://github.com/apache/hbase/blob/master/hbase-website/public/book.html

Example of copying a table with specified start and end times, peer cluster address, and column families. Note the use of --peer.adr for older versions and the recommended scanner caching and speculative execution settings.

```bash
bin/hbase org.apache.hadoop.hbase.mapreduce.CopyTable --starttime=1265875194289 --endtime=1265878794289 --peer.adr=server1,server2,server3:2181:/hbase --families=myOldCf:myNewCf,cf2,cf3 TestTable
```

--------------------------------

### Filter by Regex String Comparator

Source: https://github.com/apache/hbase/blob/master/hbase-website/app/pages/_docs/docs/_mdx/(multi-page)/architecture/client-request-filters.mdx

Use RegexStringComparator with SingleColumnValueFilter to perform regular expression matching on column values. This example filters for values starting with 'my'.

```java
RegexStringComparator comp = new RegexStringComparator("my.");   // any value that starts with 'my'
SingleColumnValueFilter filter = new SingleColumnValueFilter(
  cf,
  column,
  CompareOperaor.EQUAL,
  comp
  );
scan.setFilter(filter);
```

--------------------------------

### Minor Compaction File Selection - Example 1

Source: https://github.com/apache/hbase/blob/master/hbase-website/app/pages/_docs/docs/_mdx/(multi-page)/architecture/regions.mdx

Demonstrates a basic scenario for minor compaction file selection with specific parameters. It shows which files are selected based on size and the compaction ratio.

```text
- hbase.hstore.compaction.ratio = 1.0f
- hbase.hstore.compaction.min = 3 (files)
- hbase.hstore.compaction.max = 5 (files)
- hbase.hstore.compaction.min.size = 10 (bytes)
- hbase.hstore.compaction.max.size = 1000 (bytes)

The following StoreFiles exist: 100, 50, 23, 12, and 12 bytes apiece (oldest to newest). With the above parameters, the files that would be selected for minor compaction are 23, 12, and 12.

Why?

- 100 → No, because sum(50, 23, 12, 12) * 1.0 = 97.
- 50 → No, because sum(23, 12, 12) * 1.0 = 47.
- 23 → Yes, because sum(12, 12) * 1.0 = 24.
- 12 → Yes, because the previous file has been included, and because this does not exceed the max-file limit of 5
- 12 → Yes, because the previous file had been included, and because this does not exceed the max-file limit of 5.
```

--------------------------------

### Build Binary Tarball with Maven (Two Steps)

Source: https://github.com/apache/hbase/blob/master/hbase-website/public/book.html

Build the binary tarball using Maven. This process is recommended to be done in two steps: first installing to the local repository, then generating site documentation and assembling the tarball.

```bash
mvn clean install -DskipTests -Prelease
```

```bash
mvn install -DskipTests site assembly:single -Prelease
```

--------------------------------

### Invoke Endpoint Coprocessor from Client

Source: https://github.com/apache/hbase/blob/master/hbase-website/public/book.html

Create a connection to HBase, get a table instance, and use `coprocessorService` to invoke the endpoint. This example sends a request to the `getSum` method.

```java
Configuration conf = HBaseConfiguration.create();
Connection connection = ConnectionFactory.createConnection(conf);
TableName tableName = TableName.valueOf("users");
Table table = connection.getTable(tableName);

final Sum.SumRequest request = Sum.SumRequest.newBuilder().setFamily("salaryDet").setColumn("gross").build();
try {
    Map<byte[], Long> results = table.coprocessorService(
        Sum.SumService.class,
        null,  /* start key */
        null,  /* end   key */
        new Batch.Call<Sum.SumService, Long>() {
            @Override
            public Long call(Sum.SumService aggregate) throws IOException {
                BlockingRpcCallback<Sum.SumResponse> rpcCallback = new BlockingRpcCallback<>();
                aggregate.getSum(null, request, rpcCallback);
                Sum.SumResponse response = rpcCallback.get();

                return response.hasSum() ? response.getSum() : 0L;
            }
        });
} catch (Throwable e) {
    e.printStackTrace();
}
```

--------------------------------

### HBase REST GET: Multi-Get with URL-Encoded Filter

Source: https://github.com/apache/hbase/blob/master/hbase-website/public/book.html

Performs a Multi-Get operation with a filter specified in Thrift Filter Language and URL-encoded. This example uses PrefixFilter('row1').

```bash
curl -vi -X GET \
-H "Accept: text/xml" \
"http://example.com:8000/users/multiget?row=row1&row=row2/cf:a&filter=PrefixFilter%28%27row1%27%29"
```

--------------------------------

### LoadTestTool Example: Write and Read

Source: https://github.com/apache/hbase/blob/master/hbase-website/public/book.html

Demonstrates how to use LoadTestTool for a write and read workload. Specifies write parameters, number of keys, read verification percentage, number of tables, data block encoding, and table name.

```bash
$ hbase org.apache.hadoop.hbase.util.LoadTestTool -write 1:10:100 -num_keys 1000000
              -read 100:30 -num_tables 1 -data_block_encoding NONE -tn load_test_tool_NONE
```

--------------------------------

### Set Canary Test Timeout

Source: https://github.com/apache/hbase/blob/master/hbase-website/app/pages/_docs/docs/_mdx/(multi-page)/operational-management/tools.mdx

Enforce a timeout for Canary tests to prevent them from getting stuck on unresponsive RegionServers. This example sets the timeout to 60 seconds (60000 milliseconds).

```bash
$ ${HBASE_HOME}/bin/hbase canary -t 60000

```

--------------------------------

### Start Backup HMaster Servers

Source: https://github.com/apache/hbase/blob/master/hbase-website/public/book.html

Use the local-master-backup.sh script to start backup HMaster instances for testing. Provide port offsets to avoid conflicts with the primary HMaster.

```bash
$ ./bin/local-master-backup.sh start 2 3 5
```

--------------------------------

### Get Slow Log Responses from Specific RegionServers

Source: https://github.com/apache/hbase/blob/master/hbase-website/public/book.html

Retrieve slow log responses from a specified list of RegionServers. Server names should include host, port, and start code.

```shell
hbase> get_slowlog_responses ['SERVER_NAME1', 'SERVER_NAME2']
```

--------------------------------

### Start Local HBase Cluster

Source: https://github.com/apache/hbase/blob/master/hbase-website/app/pages/_docs/docs/_mdx/(multi-page)/building-and-developing/developer-guidelines.mdx

Run HBase directly from source in local-mode for testing changes against a more realistic cluster. Ensure HBase is installed in your local Maven repository first.

```bash
${HBASE_HOME}/bin/start-hbase.sh
```

--------------------------------

### HBase REST GET: Multi-Get with Base64 Encoded Filter

Source: https://github.com/apache/hbase/blob/master/hbase-website/public/book.html

Performs a Multi-Get operation with a filter specified in Thrift Filter Language and URL-safe base64 encoded. This example uses PrefixFilter('row1').

```bash
curl -vi -X GET \
-H "Accept: text/xml" \
"http://example.com:8000/users/multiget?row=row1&row=row2/cf:a&filter_b64=UHJlZml4RmlsdGVyKCdyb3cxJyk"
```

--------------------------------

### Override HBase Configuration in Shell

Source: https://github.com/apache/hbase/blob/master/hbase-website/app/pages/_docs/docs/_mdx/(multi-page)/shell.mdx

Override HBase configuration properties when starting the shell by using the `-D` flag followed by the configuration key and value. This example sets the ZooKeeper quorum and a custom property.

```bash
$ ./bin/hbase shell -Dhbase.zookeeper.quorum=ZK0.remote.cluster.example.org,ZK1.remote.cluster.example.org,ZK2.remote.cluster.example.org -Draining=false
...
```

```jruby
hbase(main):001:0> @shell.hbase.configuration.get("hbase.zookeeper.quorum")
=> "ZK0.remote.cluster.example.org,ZK1.remote.cluster.example.org,ZK2.remote.cluster.example.org"
hbase(main):002:0> @shell.hbase.configuration.get("raining")
=> "false"
```

--------------------------------

### HBase CompactionTool Examples

Source: https://github.com/apache/hbase/blob/master/hbase-website/public/book.html

These examples demonstrate how to use the CompactionTool for different compaction scenarios, including using MapReduce and targeting specific column families.

```bash
$ hbase org.apache.hadoop.hbase.regionserver.CompactionTool -mapred hdfs://hbase/data/default/TestTable
```

```bash
$ hbase org.apache.hadoop.hbase.regionserver.CompactionTool hdfs://hbase/data/default/TestTable/abc/x
```

--------------------------------

### Import GPG Key and Test Signing

Source: https://github.com/apache/hbase/blob/master/dev-support/create-release/README.txt

After SSHing into the VM, import your public GPG key and test the signing process. Ensure your local GPG agent is accessible via the forwarded socket.

```bash
gpg --no-autostart --import gpg.example.apache.pub
```

```bash
echo "foo" > foo.txt
```

```bash
gpg --no-autostart --detach --armor --sign foo.txt
```

```bash
gpg --no-autostart --verify foo.txt.asc
```

--------------------------------

### Integration Test with TestingHBaseCluster (HBase 2.5.0+)

Source: https://github.com/apache/hbase/blob/master/hbase-website/app/pages/_docs/docs/_mdx/(multi-page)/unit-testing.mdx

Recommended for HBase 2.5.0 and later, this example uses TestingHBaseCluster for integration tests. It includes setup and teardown methods for the cluster, connection, and admin, then performs an insert and verification.

```java
public class MyHBaseIntegrationTest {

  private TestingHBaseCluster cluster;

  private Connection conn;

  private Admin admin;

  private TableName tableName = TableName.valueOf("MyTest");

  byte[] CF = "CF".getBytes();
  byte[] CQ1 = "CQ-1".getBytes();
  byte[] CQ2 = "CQ-2".getBytes();

  @Before
  public void setUp() throws Exception {
    cluster = TestingHBaseCluster.create(TestingHBaseClusterOption.builder().build());
    cluster.start();
    conn = ConnectionFactory.createConnection(cluster.getConf());
    admin = conn.getAdmin();
    admin.createTable(TableDescriptorBuilder.newBuilder(tableName)
      .setColumnFamily(ColumnFamilyDescriptorBuilder.of(CF)).build());
  }

  @After
  public void tearDown() throws Exception {
    admin.close();
    conn.close();
    cluster.stop();
  }

  @Test
  public void testInsert() throws Exception {
    try (Table table = conn.getTable(tableName)) {
      HBaseTestObj obj = new HBaseTestObj();
      obj.setRowKey("ROWKEY-1");
      obj.setData1("DATA-1");
      obj.setData2("DATA-2");
      MyHBaseDAO.insertRecord(table, obj);
      Get get1 = new Get(Bytes.toBytes(obj.getRowKey()));
      get1.addColumn(CF, CQ1);
      Result result1 = table.get(get1);
      assertEquals(Bytes.toString(result1.getRow()), obj.getRowKey());
      assertEquals(Bytes.toString(result1.value()), obj.getData1());
      Get get2 = new Get(Bytes.toBytes(obj.getRowKey()));
      get2.addColumn(CF, CQ2);
      Result result2 = table.get(get2);
      assertEquals(Bytes.toString(result2.getRow()), obj.getRowKey());
      assertEquals(Bytes.toString(result2.value()), obj.getData2());
    }
  }
}
```

--------------------------------

### SyncTable Example Command

Source: https://github.com/apache/hbase/blob/master/hbase-website/public/book.html

Example of running SyncTable for a dry run from a remote source cluster to a local target cluster using ZooKeeper cluster keys.

```bash
$ bin/hbase org.apache.hadoop.hbase.mapreduce.SyncTable --dryrun=true --sourcezkcluster=zk1.example.com,zk2.example.com,zk3.example.com:2181:/hbase hdfs://nn:9000/hashes/tableA tableA tableA
```

--------------------------------

### HBase Table Creation, Population, Get, and Delete with Jython

Source: https://github.com/apache/hbase/blob/master/hbase-website/public/book.html

This Jython script demonstrates how to create, populate, fetch, and delete an HBase table. It includes setup for connection, table descriptor, column families, and data insertion/retrieval.

```Jython
import java.lang
from org.apache.hadoop.hbase import HBaseConfiguration, HTableDescriptor, HColumnDescriptor, TableName
from org.apache.hadoop.hbase.client import Admin, Connection, ConnectionFactory, Get, Put, Result, Table
from org.apache.hadoop.conf import Configuration

# First get a conf object.  This will read in the configuration
# that is out in your hbase-*.xml files such as location of the
# hbase master node.
conf = HBaseConfiguration.create()
connection = ConnectionFactory.createConnection(conf)
admin = connection.getAdmin()

# Create a table named 'test' that has a column family
# named 'content'.
tableName = TableName.valueOf("test")
table = connection.getTable(tableName)

desc = HTableDescriptor(tableName)
desc.addFamily(HColumnDescriptor("content"))

# Drop and recreate if it exists
if admin.tableExists(tableName):
    admin.disableTable(tableName)
    admin.deleteTable(tableName)

admin.createTable(desc)

# Add content to 'column:' on a row named 'row_x'
row = 'row_x'
put = Put(row)
put.addColumn("content", "qual", "some content")
table.put(put)

# Now fetch the content just added, returns a byte[]
get = Get(row)

result = table.get(get)
data = java.lang.String(result.getValue("content", "qual"), "UTF8")

print "The fetched row contains the value '%s'" % data
```

--------------------------------

### Example GC Log Entry: CMS-initial-mark

Source: https://github.com/apache/hbase/blob/master/hbase-website/public/book.html

This log entry indicates the start of a CMS (Concurrent Mark Sweep) garbage collection cycle, specifically the initial marking phase. The duration shown is the time the entire VM was paused.

```text
64898.952: [GC [1 CMS-initial-mark: 2811538K(3055704K)] 2812179K(3061272K), 0.0007360 secs] [Times: user=0.00 sys=0.00, real=0.00 secs]
```

--------------------------------

### Monitor System Resources with top

Source: https://github.com/apache/hbase/blob/master/hbase-website/public/book.html

Use 'top' to view real-time system process information and resource consumption. Typing 'c' expands process details, and '1' shows per-CPU usage.

```bash
top - 14:46:59 up 39 days, 11:55,  1 user,  load average: 3.75, 3.57, 3.84
Tasks: 309 total,   1 running, 308 sleeping,   0 stopped,   0 zombie
Cpu(s):  4.5%us,  1.6%sy,  0.0%ni, 91.7%id,  1.4%wa,  0.1%hi,  0.6%si,  0.0%st
Mem:  24414432k total, 24296956k used,   117476k free,     7196k buffers
Swap: 16008732k total,        14348k used, 15994384k free, 11106908k cached

  PID USER          PR  NI  VIRT  RES  SHR S %CPU %MEM        TIME+  COMMAND
15558 hadoop        18  -2 3292m 2.4g 3556 S   79 10.4   6523:52 java
13268 hadoop        18  -2 8967m 8.2g 4104 S   21 35.1   5170:30 java
 8895 hadoop        18  -2 1581m 497m 3420 S   11  2.1   4002:32 java
…
```

--------------------------------

### Build Protobuf for Apple Silicon

Source: https://github.com/apache/hbase/blob/master/hbase-website/app/pages/_docs/docs/_mdx/(multi-page)/building-and-developing/building.mdx

Commands to download, patch, configure, and build the protobuf 2.5.0 library for Apple Silicon (aarch64) and install it locally for Maven to use.

```bash
curl -sSL https://github.com/protocolbuffers/protobuf/releases/download/v2.5.0/protobuf-2.5.0.tar.gz | tar zx -
cd protobuf-2.5.0
curl -L -O https://gist.githubusercontent.com/liusheng/64aee1b27de037f8b9ccf1873b82c413/raw/118c2fce733a9a62a03281753572a45b6efb8639/protobuf-2.5.0-arm64.patch
patch -p1 < protobuf-2.5.0-arm64.patch
./configure --disable-shared
make
mvn install:install-file -DgroupId=com.google.protobuf -DartifactId=protoc -Dversion=2.5.0 -Dclassifier=osx-aarch_64 -Dpackaging=exe -Dfile=src/protoc
```

--------------------------------

### HBase MapReduce Job Setup for File Output

Source: https://github.com/apache/hbase/blob/master/hbase-website/public/book.html

Configures a MapReduce job to read from an HBase table and write summarized results to HDFS. The mapper remains the same as the table output example, but a different reducer and output path are specified.

```java
Configuration config = HBaseConfiguration.create();
    Job job = new Job(config,"ExampleSummaryToFile");
    job.setJarByClass(MySummaryFileJob.class);     // class that contains mapper and reducer
    
    Scan scan = new Scan();
    scan.setCaching(500);        // 1 is the default in Scan, which will be bad for MapReduce jobs
    scan.setCacheBlocks(false);  // don't set to true for MR jobs
    // set other scan attrs
    
    TableMapReduceUtil.initTableMapperJob(
      sourceTable,        // input table
      scan,               // Scan instance to control CF and attribute selection
      MyMapper.class,     // mapper class
      Text.class,         // mapper output key
      IntWritable.class,  // mapper output value
      job);
    job.setReducerClass(MyReducer.class);    // reducer class
    job.setNumReduceTasks(1);    // at least one, adjust as required
    FileOutputFormat.setOutputPath(job, new Path("/tmp/mr/mySummaryFile"));  // adjust directories as required
    
    boolean b = job.waitForCompletion(true);
    if (!b) {
      throw new IOException("error with job!");
    }
```

--------------------------------

### Example LoadTestTool Command for Performance Testing

Source: https://github.com/apache/hbase/blob/master/hbase-website/app/pages/_docs/docs/_mdx/(multi-page)/compression.mdx

An example command demonstrating how to use the LoadTestTool to test write and read performance with specific configurations for data block encoding and table naming.

```bash
$ hbase org.apache.hadoop.hbase.util.LoadTestTool -write 1:10:100 -num_keys 1000000 \
      -read 100:30 -num_tables 1 -data_block_encoding NONE -tn load_test_tool_NONE
```

--------------------------------

### HBase Get with Byte Array Conversion

Source: https://github.com/apache/hbase/blob/master/hbase-website/app/pages/_docs/docs/_mdx/(multi-page)/performance.mdx

This example demonstrates a common but inefficient way to retrieve data from HBase by repeatedly converting column family and attribute names to byte arrays. This can be costly, especially within loops or MapReduce jobs.

```java
Get get = new Get(rowkey);
Result r = table.get(get);
byte[] b = r.getValue(Bytes.toBytes("cf"), Bytes.toBytes("attr"));  // returns current version of value
```