Isolation levels.
A dial deciding how much of everyone else’s half-finished typing your transaction gets to see.
- 1
Both writers believe they have the document to themselves; the database decides how true that gets to be.
- I cited that line!2
A dirty read: the line was never committed, so anything built on it rests on an event that never happened.
- 3
Read committed is the floor most databases default to — drafts are invisible, only saved edits count.
- 4
Repeatable read adds a promise: once your transaction reads a line, that answer holds until you finish.
- I counted three. Now four?5
Pinning lines you have read cannot stop brand-new rows slipping into a range you already counted.
- 6
Serializable buys certainty by spending concurrency — that idle editor is healthy, just made to queue.
Semicolony semicolony.dev/eli5/isolation-levels/comic