# Working with DB shard groups
<a name="limitless-shard"></a>

You perform the following tasks to add and manage a DB shard group for Aurora PostgreSQL Limitless Database.

**Topics**
+ [Connecting to your Aurora PostgreSQL Limitless Database DB cluster](#limitless-endpoint)
+ [Finding the number of routers and shards in a DB shard group](#limitless-shard.number)
+ [Describing DB shard groups](#limitless-describe)
+ [Rebooting a DB shard group](#limitless-reboot)
+ [Changing the capacity of a DB shard group](limitless-capacity.md)
+ [Splitting a shard in a DB shard group](limitless-shard-split.md)
+ [Adding a router to a DB shard group](limitless-add-router.md)
+ [Deleting a DB shard group](limitless-shard-delete.md)
+ [Adding a DB shard group to an existing Aurora PostgreSQL Limitless Database DB cluster](limitless-shard-add.md)

## Connecting to your Aurora PostgreSQL Limitless Database DB cluster
<a name="limitless-endpoint"></a>

To work with Aurora PostgreSQL Limitless Database, you connect to the cluster writer or reader endpoint. You can use `psql` or any other connection utility that works with PostgreSQL:

```
$ psql -h DB_cluster_endpoint -p port_number -U database_username -d postgres_limitless
```

The following example uses the endpoint for the DB cluster that you created in [CLI](limitless-create-cluster.md#limitless-create-CLI).

```
$ psql -h my-limitless-cluster.cluster-ckifpdyyyxxx.us-east-1.rds.amazonaws.com -p 5432 -U postgres -d postgres_limitless
```

**Note**  
The default database for the DB shard group in Aurora PostgreSQL Limitless Database is `postgres_limitless`.

### Using the Limitless Connection Plugin
<a name="limitless-connection-plugin"></a>

When connecting to Aurora PostgreSQL Limitless Database, clients connect using the cluster endpoint, and are routed to a transaction router by Amazon Route 53. However, Route 53 is limited in its ability to load balance, and can allow uneven workloads on transaction routers. The [Limitless Connection Plugin](https://github.com/aws/aws-advanced-jdbc-wrapper/blob/main/docs/using-the-jdbc-driver/using-plugins/UsingTheLimitlessConnectionPlugin.md) for the [AWS JDBC Driver](https://github.com/awslabs/aws-advanced-jdbc-wrapper) addresses this by performing client-side load balancing with load awareness. For more information on the [AWS JDBC Driver](https://github.com/awslabs/aws-advanced-jdbc-wrapper), see [Connecting to Aurora PostgreSQL with the Amazon Web Services (AWS) JDBC Driver](Aurora.Connecting.md#Aurora.Connecting.JDBCDriverPostgreSQL).

## Finding the number of routers and shards in a DB shard group
<a name="limitless-shard.number"></a>

You can use the following query to find the number of routers and shards:

```
SELECT * FROM rds_aurora.limitless_subclusters;

 subcluster_id | subcluster_type
---------------+-----------------
 1             | router
 2             | router
 3             | shard
 4             | shard
 5             | shard
 6             | shard
```

## Describing DB shard groups
<a name="limitless-describe"></a>

Use the `describe-db-shard-groups` AWS CLI command to describe your DB shard groups. The following parameter is optional:
+ `--db-shard-group-identifier` – The name of a DB shard group.

The following example describes a specific DB shard group.

```
aws rds describe-db-shard-groups --db-shard-group-identifier my-db-shard-group
```

The output resembles the following example.

```
{
    "DBShardGroups": [
        {
            "DBShardGroupResourceId": "shardgroup-8986d309a93c4da1b1455add17abcdef",
            "DBShardGroupIdentifier": "my-shard-group",
            "DBClusterIdentifier": "my-limitless-cluster",
            "MaxACU": 1000.0,
            "ComputeRedundancy": 0,
            "Status": "available",
            "PubliclyAccessible": false,
            "Endpoint": "my-limitless-cluster.limitless-ccetp2abcdef.us-east-1.rds.amazonaws.com"
        }
    ]
}
```

## Rebooting a DB shard group
<a name="limitless-reboot"></a>

Sometimes you have to reboot your DB shard group, for example when the `max_connections` parameter changes because of a maximum capacity change.

You can use the AWS Management Console or AWS CLI to change the capacity of a DB shard group.

### Console
<a name="limitless-reboot.CON"></a>

Use the following procedure.

Sign in to the AWS Management Console and open the Amazon RDS console at [https://console.aws.amazon.com/rds/](https://console.aws.amazon.com/rds/).

1. Navigate to the **Databases** page.

1. Select the DB shard group that you want to reboot.

1. For **Actions**, choose **Reboot**.

1. Choose **Confirm**.

### CLI
<a name="limitless-reboot.CLI"></a>

To reboot a DB shard group, use the `reboot-db-shard-group` AWS CLI command with the following parameter:
+ `--db-shard-group-identifier` – The name of a DB shard group.

The following example reboots a DB shard group.

```
aws rds reboot-db-shard-group --db-shard-group-identifier my-db-shard-group
```