read committed

read uncommitted

one of the weakest consistency models; prohibits only dirty writes but permits dirty reads and other phenomena

read your writes

if a process writes a value, its subsequent reads must observe the effects of that write

repeatable read

strengthens read committed by additionally prohibiting single-object anti-dependency cycles

serializability

all transactions appear to execute in some total serial order, prohibiting dirty writes, dirty reads, and anti-dependency cycles

sequential consistency

operations appear in a total order consistent with each process's order but not necessarily real-time order

snapshot isolation

each transaction receives an isolated snapshot of the database; it commits only if no concurrent writes exist to the same keys