Caching Metrics

Available on: Self-Hosted Enterprise

Introduction

Hasura Enterprise Edition exports Prometheus metrics related to caching which can provide valuable insights into the efficiency and performance of the caching system. This can help towards monitoring and further optimization of the cache utilization.

Exposed metrics

The graphql engine exposes the hasura_cache_request_count Prometheus metric. It represents a counter and is incremented every time a request with @cached directive is served.

It has one label status, which can have values of either hit or miss.

status	description
hit	request served from the cache
miss	request served from the source (not found in cache)

Get insights from metrics

The hasura_cache_request_count metric can be used to get insights into the cache utilization by calculating the hit-miss ratio. The hit-miss ratio is the ratio of the number of requests served from the cache to the total number of requests.

hit-miss ratio = hit count / (hit count + miss count)

What does the hit-miss ratio tells us?

• Cache Efficiency: The hit-miss ratio reflects how well the caching system can serve requests from its cache. A higher hit ratio indicates more efficient cache usage, as more requests are being served from the cache rather than requiring fetching data from the upstream data source.

• Cache Performance: The hit-miss ratio is a measure of cache performance. A higher hit ratio generally indicates better cache performance as it reduces latency and improves overall system performance.

Visualize metrics

The metrics can be visualized using a tool like Grafana.

Sample PromQL Queries

• Total requests per minute with @cached directive: sum(increase(hasura_cache_request_count[1m]))
• hit requests per minute: increase(hasura_cache_request_count{status="hit"}[1m])
• miss requests per minute: increase(hasura_cache_request_count{status="miss"}[1m])
• Hit-Miss ratio over lifetime: sum(hasura_cache_request_count{status="hit"})/sum(hasura_cache_request_count)