What methods can prevent transaction splitting when using database sharding?

When sharding a database, transactions that span multiple shards can be difficult to maintain due to data distribution. To prevent transaction splitting, the following approaches can be used:

• Local transactions: design the system so that transactions only affect data on a single shard.
• Using distributed transactions: apply two-phase commit (2PC) protocols, but this reduces performance and complicates the system.
• Shard key identification: ensure that operations within a transaction use the same shard key.
• Sagas: break long transactions into a sequence of local transactions with compensating actions in case of errors.

For example, if you have an orders table sharded by customer ID, all operations for a single customer should be performed within the same shard to avoid distributed transactions.