From the end of January to early February, the Chinese New Year period required on-call support to ensure system stability. During this time, the best possible outcome is simple: no incidents. Fortunately, everything remained stable, and no major issues occurred.

This week, I mainly evaluated the impact of a new business requirement. One important lesson I have learned is that, when working on complex systems—especially those you are not fully familiar with—the safest approach is to minimize changes as much as possible.

This is not about being overly conservative, but about controlling uncertainty. In large systems, there are often hidden dependencies and non-obvious logic paths. Making broad or intrusive changes without a deep understanding can easily introduce subtle issues that may only surface much later.

This insight comes from experience. By the time I wrote this, I had already encountered similar situations more than once. In one case, I made a significant modification to a service. Everything appeared to work correctly during testing and shortly after deployment. However, weeks later, I discovered that the change had unintentionally affected a chain of upstream and downstream interactions.

In systems that have evolved over time and passed through multiple hands, there is always hidden complexity. Some mechanisms may not be immediately visible but are critical to the overall system behavior. As a general rule: avoid modifying core logic or frameworks unless absolutely necessary.

In addition to this evaluation work, I also resolved an issue related to a security encryption service that was not compatible with Chinese characters.

The root cause was that the service directly used plaintext input as Redis keys. When the input contained Chinese characters, the keys could be stored successfully but could not be reliably retrieved due to encoding inconsistencies.

To fix this, I changed the key generation strategy. Instead of using the original plaintext, I applied a hash function to generate the Redis key. This approach has several advantages:

  • avoids encoding and compatibility issues
  • ensures consistent key lookup
  • improves security by not exposing raw business data in keys

This change made the system more robust and predictable.