Original Thread: Discord
Thread ID: ch_5de0d787
Messages Count: 8
Copied on: 2025-07-28T17:54:26.552Z
Problem/Question
A developer was seeking guidance on the gas cost differences between dynamic fields (DFs) and dynamic object fields (DOFs) in Move programming. They wanted to understand the performance implications for various operations including creating, reading, and editing objects. Additionally, they were looking for methods to measure and compare gas costs between different implementation approaches to make informed decisions about which coding patterns to use for optimal gas efficiency.
Discussion Points
- Comparison of gas costs between dynamic fields and dynamic object fields across different operations
- General recommendations and best practices for choosing between DFs and DOFs
- Methods for measuring and comparing gas costs without incurring actual transaction fees
- The trade-offs between functionality and gas efficiency when using different field types
- Practical testing approaches to validate theoretical recommendations
Solutions/Approaches
General Recommendation:
The Move documentation provides clear guidance favoring dynamic fields over dynamic object fields when direct discovery through ID is not required. As stated in the Move book (Dynamic Object Fields | The Move Book), dynamic object fields should be avoided unless their specific benefits justify the additional costs.
Gas Cost Measurement Method:
To compare gas costs between different implementations, developers can create multiple versions of their functions and execute dry runs of each approach. This technique allows for cost analysis without paying actual transaction fees.
Empirical Testing Results:
Through practical testing, the following gas cost differences were identified:
Creation Operations:
- Dynamic object fields consume approximately 2x more storage gas compared to dynamic fields
- Dynamic object fields require about 2.5x more computation gas than dynamic fields
Reading Operations:
- Both field types incur no storage gas costs for read operations
- Dynamic fields have negligible computation gas costs (testing showed the ability to read 500 DFs in a single transaction without reaching the 1,000,000 MIST limit)
- Dynamic object fields have measurable computation costs (reading 500 DOFs in a single transaction reached approximately 1,300,000 MIST in computation gas cost, exceeding the 1,000,000 MIST limit)
Key Insights:
- The choice between dynamic fields and dynamic object fields becomes particularly important for transactions involving large numbers of objects
- Dynamic fields offer significantly better gas efficiency for both creation and reading operations
- The performance difference is substantial enough to warrant careful consideration during the design phase
- Empirical testing confirmed the theoretical recommendations found in the Move documentation
Best Practice:
For applications processing many objects in single transactions, selecting dynamic fields over dynamic object fields can result in meaningful gas savings and should be the preferred approach unless the specific functionality of dynamic object fields is essential.