OpenAI Prompt Caching

OpenAI is offering automatic token discounts on inputs that the model has recently seen…

Cobus Greyling
3 min readOct 9, 2024

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OpenAI’s Prompt Caching feature stores and reuses frequently used prompts within the API, which helps to reduce latency and improve response times for commonly repeated queries.

In Short…

Prompt Caching is enabled by default on the latest GPT-4o and GPT-4o mini models, including their fine-tuned versions.

This feature provides cached prompts at a reduced rate compared to standard prompts, offering an efficient option for frequently repeated queries while lowering costs.

Caches are usually cleared after 5 to 10 minutes of inactivity and are automatically deleted within an hour of their last use.

This feature is intended to help developers scale their applications effectively while managing performance, costs, and latency.

{
"usage": {
"prompt_tokens": 36,
"completion_tokens": 300,
"total_tokens": 336,
"prompt_tokens_details": {
"cached_tokens": 0
},
"completion_tokens_details": {
"reasoning_tokens": 0
}
}
}

Risk In Offloading Functionality

Yes, there is a potential risk of becoming overly dependent on the model when offloading functionality like caching to it.

Relying too much on the model could reduce control over data management and limit flexibility to adapt caching strategies based on specific application needs.

Additionally, any changes or limitations in the model’s caching implementation might affect the system’s overall performance.

Therefore, it’s essential to balance between leveraging built-in features and maintaining some autonomy over critical components.

Caching vs Seeding

Prompt Caching and seeding serve different purposes in AI model usage.

Prompt Caching stores frequently used prompts for faster access, reducing latency in repeated queries.

Seeding, however, initializes the model with specific parameters or initial values to ensure consistent output across similar prompts.

Essentially, Prompt Caching speeds up response time by reusing cached prompts, while seeding aims to maintain consistent results across various runs by setting an initial state.

Granular Control Over Caching

Currently, OpenAI’s API does not offer a specific command to directly monitor prompt caching.

Typically, caching behaviour is managed on the backend by OpenAI, so developers don’t have direct access to a cache monitoring interface.

However, developers can indirectly monitor caching effectiveness by tracking response times or using logging to see if repeated prompts are served faster, which might indicate they are being cached.

For any precise tools or updates, checking OpenAI’s API documentation or support resources is recommended.

In Conclusion

OpenAI’s prompt caching raises concerns about users becoming more dependent on the model and transferring significant functionality to it.

This shift may result in a lack of granular control over operations, which could impact user experience.

However, the primary advantage of prompt caching lies in its automatic benefits for existing users, allowing them to leverage this feature without additional effort.

Overall, while there are challenges, the potential for improved performance remains significant.

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Chief Evangelist @ Kore.ai | I’m passionate about exploring the intersection of AI and language. From Language Models, AI Agents to Agentic Applications, Development Frameworks & Data-Centric Productivity Tools, I share insights and ideas on how these technologies are shaping the future.

https://openai.com/index/api-prompt-caching/

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