Connecting to a Timestream for InfluxDB read replica DB cluster

PDFRSS

A Timestream for InfluxDB read replica DB cluster has two reachable DB instances instead of a single DB instance. Each connection is handled by a specific DB instance. When you connect to a read replica DB cluster, the hostname and port that you specify point to a fully qualified domain name called an endpoint.

The primary (writer) endpoint connects to the writer DB instance of the read replica DB cluster, which supports both read and write operations. The reader endpoint connects to the reader DB instance, which support only read operations.

Using endpoints, you can map each connection to the appropriate DB instance based on your use case. For example, to perform administrative or write statements, you can connect to whichever DB instance is the writer DB instance. To perform queries, you can connect to the reader endpoint. For diagnosis or tuning, you can connect to a specific DB instance endpoint, /metrics, to examine details about a specific DB instance.

For information about connecting to a DB instance, see Connecting to an Amazon Timestream for InfluxDB DB instance. For more information about connecting to read replica clusters, see the following topics.

Types of read replica cluster endpoints

An endpoint is represented by a unique identifier that contains a host address. Each Timestream for InfluxDB cluster has:

• A cluster endpoint.

• A cluster read-only endpoint.

• An instance endpoint for each instance in the cluster.

Cluster endpoint

A cluster endpoint (or writer endpoint) for a read replica cluster connects to the current writer DB instance for that DB cluster. This endpoint is the only one that can perform write operations such as:

• InfluxDB-specific administrative commands, e.g., creating, modifying, or deleting organizations, users, buckets, tasks, etc.

• Writing data to your database cluster.

You use the cluster endpoint for all write operations on the DB cluster, including writes, upserts, deletes, and all configuration and administrative changes.

In addition, you can use the cluster endpoint for read operations, such as queries.

If the current writer DB instance of a DB cluster fails, the read replica cluster automatically fails over to one of its replicas, promoting it as the new writer DB instance. During a failover, the DB cluster continues to serve connection requests to the cluster endpoint from the new writer DB instance, with minimal interruption of service. The read replica endpoint that was promoted to writer will stop serving reads until a new replica is deployed.

The following example illustrates a cluster endpoint for a read replica cluster:

ipvtdwa5se-wmyjrrjko.us-west-2.timestream-influxdb.amazonaws.com

Read-only endpoint

The read-only endpoint connects to any one of the read replica instances in the cluster. Read replicas will only support read operations, such as Flux or InfluxQL queries; in other words, all operations executed against the /api/v2/query endpoint for Flux queries or /api/query endpoint for InfluxQL v1-compatible queries. By processing those statements on the reader DB instances, this endpoint reduces the overhead on the writer DB instance. It also helps the cluster to handle a higher number of simultaneous queries.

The following example illustrates a reader endpoint for a read replica cluster. The read-only intent of a reader endpoint is denoted by the -ro within the cluster endpoint name.

ipvtdwa5se-wmyjrrjko-ro.us-west-2.timestream-influxdb.amazonaws.com

Instance endpoint

An instance endpoint connects to a specific DB instance within a read replica cluster. Each DB instance in a DB cluster has its own unique instance endpoint. Therefore, there is one instance endpoint for the current writer DB instance of the DB cluster (the primary), and there is one instance endpoint for each of the reader DB instances in the DB cluster.

The instance endpoint provides direct control over connections to the DB cluster. This control can help you address scenarios where using the cluster endpoint or reader endpoint might not be appropriate. For example, your client application might require more fine-grained load balancing based on workload type. In this case, you can configure multiple clients to connect to different reader DB instances in a DB cluster to distribute read workloads.

The following example illustrates an instance endpoint for a DB instance in a read replica cluster:

mydbinstance-123456789012.us-east-1.timestream-influxdb.amazonaws.com