Enum IsolationLevel 

#[non_exhaustive]
pub enum IsolationLevel {
    ReadCommitted,
    SnapshotIsolation,
    Serializable,
}

Transaction isolation level.

Controls the consistency guarantees and performance tradeoffs for transactions.

Comparison

Level	Dirty Reads	Non-Repeatable Reads	Phantom Reads	Write Skew
ReadCommitted	No	Yes	Yes	Yes
SnapshotIsolation	No	No	No	Yes
Serializable	No	No	No	No

Performance

Higher isolation levels require more bookkeeping:

• ReadCommitted: Only tracks writes
• SnapshotIsolation: Tracks writes + snapshot versioning
• Serializable: Tracks writes + reads + SSI validation

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

ReadCommitted

Read Committed: sees only committed data, but may see different versions of the same row within a transaction.

Lowest overhead, highest throughput, but weaker consistency.

SnapshotIsolation

Snapshot Isolation (default): each transaction sees a consistent snapshot as of transaction start. Prevents non-repeatable reads and phantom reads.

Vulnerable to write skew anomaly.

Serializable

Serializable Snapshot Isolation (SSI): provides full serializability by detecting read-write conflicts in addition to write-write conflicts.

Prevents all anomalies including write skew, but may abort more transactions due to stricter conflict detection.

Trait Implementations

impl Clone for IsolationLevel

fn clone(&self) -> IsolationLevel

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for IsolationLevel

impl Debug for IsolationLevel

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for IsolationLevel

fn default() -> IsolationLevel

Returns the “default value” for a type.

impl Eq for IsolationLevel

impl PartialEq for IsolationLevel

fn eq(&self, other: &IsolationLevel) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for IsolationLevel