Anti Entropy

Is a mechanism that can be used to detect inconsistency between a replica system.

The mechanism uses Merkle tree to compare the differences in different level of nodes

Passive anti-entropy

Trigger: READ operation

This is a on-demand anti-entropy request, typically happen during READ operation that system detects inconsistent from other node. If the node has old data (from comparing the digest hash), the coordinator update that node only

[!danger]
This will not use Merkle tree and only send 1 row data to the affected node. This is to optimise speed

[!note]
For WRITE operation, since we just gonna write to the latest, we won't have this problem

Active anti-entropy

Trigger: Scheduled background process that would typically happen during off-peak time.

This will use Merkle tree to detect just the changes that need to fix up instead of sending the whole data over the internet