Persistence & WAL

To ensure data durability and fast recovery, Iris implements a Write-Ahead Log (WAL) system.

Write-Ahead Log (WAL)

• All incoming write operations (Add, Delete) are immediately appended to a disk-based log file.
• This happens before memory structures (like HNSW graph or Inverted Index) are updated.
• In case of a crash, Iris replays the WAL on startup to restore the in-memory state.

Segments

Indexes can be split into segments (though currently, the implementation focuses on a global segment model with potential for expansion).

• Larger indexes are safer to manage as smaller, immutable segments that are periodically merged.

Checkpointing

Currently, explicit commits flush the in-memory state to durable index files.

#![allow(unused)]
fn main() {
engine.commit()?;  // Flush and persist all changes
}