Enum TransactionMode 

pub enum TransactionMode {
    Default,
    Deferred,
    Immediate,
    Exclusive,
}

How a transaction acquires write locks.

Orthogonal to IsolationLevel: an isolation level describes what anomalies a transaction can observe; a mode describes when the transaction acquires its locks.

Only SQLite (and SQLite-compatible engines) currently expose this dimension to clients:

• Default → whatever the driver picks. For SQLite that is BEGIN (DEFERRED) today; for a future driver it may not be — e.g. Turso under MVCC plans to default to BEGIN CONCURRENT.
• Deferred → BEGIN (DEFERRED): explicit deferred locking. Identical to Default on plain SQLite; on a driver whose default is not deferred (Turso MVCC), this is how the caller opts out of that default.
• Immediate → BEGIN IMMEDIATE: write lock acquired up front, so a later write inside the transaction cannot fail with SQLITE_BUSY.
• Exclusive → BEGIN EXCLUSIVE: exclusive lock held for the lifetime of the transaction; no other connection — reader or writer — can make progress against the database file.

Drivers that do not implement a given mode return Error::unsupported_feature when the transaction starts. Future drivers may extend this enum (e.g. a Turso Concurrent variant for BEGIN CONCURRENT under MVCC).

Variants

Default

The driver’s natural default. May differ from Deferred on drivers that prefer a different locking strategy (e.g. Turso MVCC → BEGIN CONCURRENT).

Deferred

Explicit deferred locking. SQLite → BEGIN (DEFERRED). Use this to override a driver whose Default is not deferred.

Immediate

Acquire a write lock when the transaction begins. SQLite → BEGIN IMMEDIATE. Rejected by drivers without an equivalent.

Exclusive

Hold an exclusive lock for the entire transaction. SQLite → BEGIN EXCLUSIVE. Rejected by drivers without an equivalent.

Trait Implementations

impl Clone for TransactionMode

fn clone(&self) -> TransactionMode

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for TransactionMode

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

Formats the value using the given formatter.

impl Default for TransactionMode

fn default() -> TransactionMode

Returns the “default value” for a type.

impl PartialEq for TransactionMode

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for TransactionMode

impl Eq for TransactionMode

impl StructuralPartialEq for TransactionMode