database sharding versus replication which one should you pick

hey folks, i've been thinking a lot about scaling databases lately. we're hitting some limits with our current setup, and i'm weighing the options between sharding and replication. replication seems straightforward for read scaling and availability, but sharding feels like the next step for handling massive datasets and write loads. what are your experiences? when did you decide sharding was necessary over just adding more replicas? are there any hybrid approaches you've seen work well? curious about the trade-offs you encountered