Cache
Every cache operation a recorded request performed: what it asked for, whether it was there, and what it wrote.
What turns it on
Cache operations are collected inside a request, so requests.track_requests is the switch and the application has to accept Requests.
What is recorded
| Field | What it is |
|---|---|
| Operation | Hit, miss, write or forget. |
| Store | Which cache store it went to. |
| Key prefix | The part of the key before the first colon. |
| TTL | On a write, how long it was written for. |
Keys are cut at the colon
Laravel's keys are routinely prefix:id, and those two halves are different things: the prefix is the diagnostic part, the id is who the row belongs to. What is stored is the part up to the first colon, and a key with no colon is truncated.
'capture_cache_keys' => env('LB_REQUEST_CAPTURE_CACHE_KEYS', false),
Turn it on to keep whole keys, up to 255 characters, when the id is the thing you are chasing.
What it answers
A hit ratio is only interesting per endpoint. A page that misses the same key on every request has a cache that is not working, and reading that against the same request's queries is usually the whole diagnosis: the misses and the query they cause are in the same waterfall.
max_cache_events keeps a hundred operations per request, with the counters running past it.