Cache and Sessions

Cache-aside pattern

App checks Redis first; on a miss, load from the database, then SET with a TTL.

GET cache:product:42
# miss -> query DB, then:
SET cache:product:42 "{\"name\":\"Tee\"}" EX 300

Invalidate on write

When the source data changes, delete or overwrite the cache key so readers do not see stale values forever.

DEL cache:product:42

Sessions

Store a session id in a cookie; keep session data in Redis with an expiry matching idle timeout.

SET session:S3cr3t "{\"userId\":7}" EX 86400
GET session:S3cr3t

Keep payloads lean

Cache only what you need. Huge values waste memory and network. Prefer hashes or compact JSON.