Fixing Azure Cache for Redis key mismatches: trailing spaces, inconsistent GET vs iteration, and safe SCAN patterns

Troubleshoot Azure Cache for Redis mismatches: trailing-space keys causing different values in iteration vs GET. Use SCAN and verify with Redis Insights.

When reading data from Azure Cache for Redis, it’s tempting to just iterate over keys and fetch values. Sometimes, though, the values you see in a bulk pass don’t match what you get from a direct GET, and tools like Redis Insights mirror the direct-read result. This guide walks through a real-world case of such a mismatch and how to resolve it cleanly.

Minimal example that surfaces the mismatch

The scenario starts with a straightforward sweep across keys followed by a direct lookup that returns something different. Here’s the pattern that exposed the problem:

key_ids = rds.keys()
for k in key_ids:
    v = rds.get(k)

And here’s the direct read that didn’t align with the sweep:

rds.get('my_key')

What’s actually going on

The inconsistency traced back to a deceptively simple cause: there were two separate keys that looked the same at a glance, but one had a trailing space. In Redis, strings are exact, so these are distinct entries. That’s why reading a specific literal returns one value, while a key iteration could surface the other one. The difference becomes evident when you fetch both explicitly:

rds.get('my_key')
rds.get('my_key ')

Since Redis Insights showed the same value as the direct literal, it was reading the exact key string without the trailing space, matching the hardcoded GET. The sweep, however, included the other entry as well, making the results appear inconsistent.

Fixing the issue and reading keys safely

The resolution in this case was simply acknowledging the presence of two distinct keys—one with a trailing space—and addressing that discrepancy. Beyond that specific fix, when iterating through Redis keys, a safer approach is to use SCAN to iterate rather than a single-shot keys list. The following snippet shows a safe iteration pattern that also makes it easy to spot and handle exact key names:

cursor = 0
while True:
    cursor, batch_keys = rds.scan(cursor=cursor)
    for name in batch_keys:
        payload = rds.get(name)
    if cursor == 0:
        break

And when a value seems off in a sweep versus a direct read, test the exact strings explicitly, including potential trailing whitespace:

rds.get('my_key')
rds.get('my_key ')

Why this detail matters

Invisible whitespace in key names can lead to confusing read paths and time-consuming debugging. In cache-backed systems and observability tools, identical-looking labels may not be identical strings. The result is misleading differences between bulk reads, ad-hoc GETs, and what dashboards display. A disciplined check for trailing spaces or other subtle characters in key names pays off immediately when you hit odd discrepancies.

Takeaways

When a value read by key iteration doesn’t match a direct GET in Azure Cache for Redis or looks different from Redis Insights, verify the exact key strings. A trailing space turns a familiar key into a separate entry, which explains why a sweep and a hardcoded GET can disagree. Prefer SCAN for iterating keys and validate key literals explicitly to avoid chasing phantom inconsistencies.