thanos-io/thanos · error

not found key in results

Error message

not found key %s in results

What it means

RedisClient.MGet builds a reply map from the MGET response and requires every requested key to be present in that map. If a key is missing from the server's reply (protocol mismatch, key eviction race between request build and reply parse) it returns this error naming the key.

Solutions

1. Deduplicate the key list before calling MGet — duplicates collapse in the reply map.
2. Treat the missing key as a cache miss instead: wrap MGet and substitute nil for absent keys.
3. Check for cluster/proxy behavior that truncates MGET replies and fall back to per-key GETs.
4. Log the key from the error and verify it was part of the original request batch.

Example fix

// before
vals, err := client.MGet(ctx, keys)
// after: dedupe before the call
uniq := make([]string, 0, len(keys))
seen := map[string]struct{}{}
for _, k := range keys {
    if _, ok := seen[k]; !ok { seen[k] = struct{}{}; uniq = append(uniq, k) }
}
vals, err := client.MGet(ctx, uniq)

uniq := make([]string, 0, len(keys))
seen := map[string]struct{}{}
for _, k := range keys { if _, ok := seen[k]; !ok { seen[k] = struct{}{}; uniq = append(uniq, k) } }
keys = uniq

vals, err := client.MGet(ctx, keys)
if err != nil && strings.Contains(err.Error(), "not found key") {
    log.Warnf("treating MGet failure as cache miss: %v", err)
    vals = nil // fall through to recompute and repopulate
}

When it happens

Trigger: Calling MGet(ctx, keys) and the returned rueidis reply map lacks one of the requested keys, so mgetRet[k] lookup fails with ok==false.

Common situations: Duplicate keys requested causing reply-map key collisions; proxy/cluster client dropping keys; mismatch between key list sent and reply parsed after a partial failure.

Understand the failure class

Background: Record Not Found Errors: "not found", RecordNotFound, and "was not found" — what they mean and how to fix them — this error's family across 28 libraries.

Related errors

• failed to convert resp to string
• creating redis client
• converting PING response to string
• redis: Unexpected PING response
• MSet the length of keys and values not equal, len(keys)=

AI-assisted analysis of thanos-io/thanos@35b8b99117 (2026-09-07). Data as JSON: /api/errors/44612df97326b2ea. Report an issue: GitHub.

Appendix: source

Thrown at internal/cortex/chunk/cache/redis_client.go:145

}

func (c *RedisClient) MGet(ctx context.Context, keys []string) ([][]byte, error) {
	var cancel context.CancelFunc
	if c.timeout > 0 {
		ctx, cancel = context.WithTimeout(ctx, c.timeout)
		defer cancel()
	}

	ret := make([][]byte, 0, len(keys))

	mgetRet, err := rueidis.MGet(c.rdb, ctx, keys)
	if err != nil {
		return nil, err
	}
	for _, k := range keys {
		m, ok := mgetRet[k]
		if !ok {
			return nil, errors.Errorf("not found key %s in results", k)
		}
		if m.IsNil() {
			ret = append(ret, nil)
			continue
		}
		r, err := m.ToString()
		if err != nil {
			return nil, errors.Errorf("failed to convert %s resp to string", k)
		}
		ret = append(ret, stringToBytes(r))
	}

	return ret, nil
}

func (c *RedisClient) Close() error {
	c.rdb.Close()
	return nil

View on GitHub (pinned to 35b8b99117)