How does BGSAVE work?

BGSAVE is a command in Redis that triggers a background save of the dataset to disk. Here’s how it works:

1. Forking: When you issue the BGSAVE command, Redis creates a child process using the fork() system call. This child process will handle the saving of the dataset.

2. Saving: The child process writes the current dataset to a dump file (usually named dump.rdb) in the specified directory. This operation is performed in the background, allowing the main Redis server to continue processing commands without blocking.

3. Completion: Once the child process completes the saving operation, it exits. Redis will then have a snapshot of the dataset saved to disk.

4. Notifications: After the save is complete, Redis can notify clients that the save operation has finished.

This mechanism allows Redis to persist data without interrupting the service, making it suitable for high-performance applications.