Databaser bliver ofte til en flaskehals når systemer vokser. Skalering af dem indebærer teknikker som replikering (kopier til læseskalering og tilgængelighed), sharding (opdeling af data på tværs af servere), caching og valg af passende databasetyper.
Replikering — kopier af dataene
REPLICATION → maintain COPIES of the database across servers:
→ PRIMARY (writes) + REPLICAS (copies):
- READ SCALING → direct reads to replicas (offload the primary) → handle more reads
- AVAILABILITY → a replica can take over if the primary fails (failover)
⚠️ replication lag → replicas may be slightly behind (eventual consistency for reads)
→ great for READ-heavy workloads and availability (most apps are read-heavy)
