# ACU Utilization on AWS Aurora Serverless

# Introduction
Do open connections affect the ACU utilization on aws aurora serverless?

# Answer
Yes, open connections can affect the ACU (Aurora Capacity Unit) utilization on AWS Aurora Serverless.

## Specifically:

-   **Connection Management and Scaling:**

    Aurora Serverless v2 scales its capacity (in ACUs) based on the load, which includes CPU utilization, memory usage, network bandwidth, and the number of active connections. A higher number of open connections, even if idle, can contribute to the perceived load and potentially influence the scaling behavior, leading to higher ACU consumption.

-   **Preventing Scale-to-Zero:**

    For Aurora Serverless v2, if the minimum capacity is set to 0 ACUs, the instance can automatically pause after a period of inactivity. However, any open connections, even idle ones, will prevent the instance from pausing and scaling down to 0 ACUs, incurring compute charges.

-   **Resource Consumption:**

    Establishing and maintaining database connections consumes resources (compute and memory) on the database server. A large number of open connections, especially if frequently opened and closed by serverless applications without proper connection pooling, can lead to increased resource consumption and potentially higher ACU utilization.

-   `max_connections` Parameter:

    The `max_connections` parameter directly impacts the maximum number of concurrent connections allowed. While it doesn't directly dictate ACU usage, if the configured `max_connections` value necessitates a higher baseline of resources, it can influence the minimum ACU the instance maintains, even during periods of low activity.

# Conclusion
For efficient connection management, the use of connection pooling (e.g., with Amazon RDS Proxy or application-level pooling), is crucial for optimizing ACU utilization and cost in Aurora Serverless environments, particularly for workloads with fluctuating connection demands.