Two Building Blocks
A full backup copies the entire database at a point in time. It is simple to restore from because everything you need lives in one place, but it is slow to take and large to store. An incremental backup copies only the blocks or rows changed since the previous backup. It is fast and small, but a restore must replay a chain.
The Common Pattern
Most schedules combine the two:
- Take a full backup weekly as an anchor.
- Take incremental backups daily or hourly between fulls.
- A restore loads the last full, then applies each incremental in order.
A differential backup is a middle ground: it copies everything changed since the last full, so a restore needs only the full plus one differential.
The Tradeoff
More frequent fulls cost storage and backup time but make restores fast and simple. More incrementals save space but lengthen the restore chain and add risk, because a single corrupt increment can break the whole sequence.
Key idea
Full backups restore fast but cost storage and time, incrementals are cheap to take but slow and fragile to restore, so real schedules anchor periodic fulls with cheaper increments between them.