Synchronization process in Redis - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the synchronization process in Redis?

The synchronization process in Redis ensures that data between the master and replica servers is consistent and up to date.

intermediate

What happens during a full synchronization in Redis replication?

During full synchronization, the replica requests a complete copy of the master's dataset, which is sent as an RDB file, and then applies any new commands received after the snapshot.

intermediate

What is partial synchronization in Redis and when is it used?

Partial synchronization is used when the replica reconnects and the master's replication backlog still contains the missing data, allowing the replica to catch up without a full data transfer.

intermediate

What is the role of the replication backlog in Redis synchronization?

The replication backlog is a fixed-size buffer on the master that stores recent write commands to help replicas perform partial synchronization without needing a full resync.

beginner

Why is synchronization important for Redis replicas?

Synchronization keeps replicas updated with the master's data, ensuring high availability, fault tolerance, and load distribution in Redis setups.

What triggers a full synchronization in Redis replication?

A Replica connects for the first time or backlog is missing

B Replica has all data up to date

C Master restarts without data loss

D Replica disconnects briefly

A full synchronization happens when a replica connects for the first time or when the master's backlog does not contain the missing data.

What does Redis send to the replica during full synchronization?

A Only the latest commands

B A snapshot of the dataset as an RDB file

C A list of keys to delete

D Nothing, replica fetches data itself

During full sync, Redis sends the replica a snapshot of the dataset as an RDB file.

What is the replication backlog used for in Redis?

A To backup the entire database

B To store user passwords

C To store recent write commands for partial sync

D To log errors

The replication backlog stores recent write commands to help replicas catch up during partial synchronization.

Which synchronization type is faster when possible in Redis replication?

A Partial synchronization

B Full synchronization

C Manual synchronization

D No synchronization

Partial synchronization is faster because it only sends missing commands instead of the full dataset.

What happens if the replication backlog is too small in Redis?

A Replication stops completely

B Data is lost permanently

C Master crashes

D Replicas may need full synchronization more often

If the backlog is too small, replicas might miss data and require full synchronization more frequently.

Explain the difference between full synchronization and partial synchronization in Redis replication.

Think about how replicas catch up with the master after disconnects.

Describe the role of the replication backlog in Redis synchronization and why it is important.

Consider how Redis avoids sending full data every time a replica reconnects.