Cache Miss

What it is

A cache miss means the requested data is not in the cache.

The system must fetch it from the original source and may populate the cache afterward.

When it matters

A miss matters because it usually increases:

• latency
• database load
• response variability

It also affects warm-up behavior and what happens after invalidation.

Common mistake

The classic mistake is treating every miss as a defect.

Not every miss is bad.

The real problem is when misses happen too often or at the wrong time.

Better question

Before judging it, ask:

1. was this miss expected?
2. did it come from healthy expiration or a weak strategy?
3. can the system safely fall back to the original source?