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UsingTheAuroraInitialConnectionStrategyPlugin.md

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Aurora Initial Connection Strategy Plugin

The Aurora Initial Connection Strategy Plugin allows users to configure their initial connection strategy, and it can also be used to obtain a connection more reliably if DNS is updating by replacing an out of date endpoint. When the Aurora Initial Connection Strategy Plugin attempts to make a connection, it may retry the connection attempt if there is a failure. Users are able to configure how often to retry a connection and the maximum allowed time to obtain a connection using the connection parameters.

When this plugin is enabled, if the initial connection is to a reader cluster endpoint, the connected reader host will be chosen based on the configured strategy. The initial connection strategy specifies how the driver determines which available reader to connect to.

This plugin also helps retrieve connections more reliably. When a user connects to a cluster endpoint, the actual instance for a new connection is resolved by DNS. During failover, the cluster elects another instance to be the writer. While DNS is updating, which can take up to 40-60 seconds, if a user tries to connect to the cluster endpoint, they may be connecting to an old instance. This plugin helps by replacing the out of date endpoint if DNS is updating.

Enabling the Aurora Initial Connection Strategy Plugin

To enable the Aurora Initial Connection Strategy Plugin, add initialConnection to the plugins connection parameter.

Aurora Initial Connection Strategy Connection Parameters

The following properties can be used to configure the Aurora Initial Connection Strategy Plugin.

Parameter Value Required Description Example Default Value
readerHostSelectorStrategy String No The strategy that will be used to select a new reader host when opening a new connection.

For more information on the available reader selection strategies, see this table.		 leastConnections random
openConnectionRetryTimeoutMs Number No The maximum allowed time for retries when opening a connection in milliseconds. 40000 30000
openConnectionRetryIntervalMs Number No The time between retries when opening a connection in milliseconds. 2000 1000

Examples

Enabling the plugin:

params = {
  plugins: "initialConnection"
  // Add additional connection parameters here
};

// If using MySQL:

const client = new AwsMySQLClient(params);
await client.connect();

// If using PostgreSQL:

const client = new AwsPGClient(params);
await client.connect();

Configuring the plugin using the connection parameters:

params = {
  openConnectionRetryTimeoutMs: 40000
  // Add additional connection parameters here
};

// If using MySQL:

const client = new AwsMySQLClient(params);
await client.connect();

// If using PostgreSQL:

const client = new AwsPGClient(params);
await client.connect();