Athena Cloudwatch Metrics Connector Issue

The error you're encountering is due to CloudWatch API throttling when querying the 'metric_samples' table. This happens because the Athena CloudWatch Metrics connector is making too many requests to the CloudWatch API in a short period of time, causing CloudWatch to reject requests with a "Rate exceeded" error.

Here are some suggestions to resolve this issue:

1. Narrow your query scope: Add more specific filters to your query to reduce the amount of data being processed. For example, limit the time range or add filters for specific namespaces, metric names, or dimensions.

2. Implement query throttling: The connector supports Amazon Intelligent Tiering (AIMD) for handling throttling events. Check your connector configuration to ensure this feature is properly enabled.

3. Increase the Lambda timeout: If your queries are timing out, consider increasing the timeout setting for the Lambda function that powers the connector.

4. Check IAM permissions: Verify that the connector has the required permissions, particularly the "CloudWatch Metrics ReadOnly" permission which is needed to query metrics data.

5. Optimize your query: Break larger queries into smaller ones that can be executed sequentially to avoid hitting rate limits.

6. Request service quota increase: If you consistently need to query large volumes of metric data, consider requesting a CloudWatch API rate limit increase from AWS Support.

The connector is designed to handle throttling events, but particularly large queries against the 'metric_samples' table can still trigger CloudWatch API rate limits due to the volume of data being requested.
Sources
Amazon Athena CloudWatch Metrics connector - Amazon Athena
AWS Cloudwatch Metric | AWS re:Post