Transactions & Consistency
What happens when two requests touch the same row at the same time, and which anomalies your isolation level still allows.
5 topics
ACID & What Each Letter Buys
What a transaction actually guarantees, and why "I" is the only letter you have to make decisions about.
core20 minIsolation Levels & Anomalies
Each isolation level is defined by which concurrency anomalies it still allows — and read committed, the default, allows several.
core30 minMVCC & Snapshots
How Postgres lets readers and writers avoid blocking each other by keeping multiple versions of every row.
core20 minLocking & Deadlocks
Which locks a statement takes, why two transactions can end up waiting on each other, and how to make that impossible.
core20 minOptimistic vs Pessimistic Concurrency
Lock the row up front or detect the conflict at write time — and which one a collaborative UI actually wants.
core20 min