Struct MigrationWatermark 

pub struct MigrationWatermark {
    pub mvcc_format_version: u32,
    pub watermark: HlcTimestamp,
}

Durable migration state for the legacy-to-HLC cut-over (spec section 8.4).

The database stores both fields. The format is always explicit; it is never inferred from byte length.

Fields

mvcc_format_version: u32

Explicit MVCC storage format version (see Self::FORMAT_LEGACY_EPOCH and Self::FORMAT_HLC).

watermark: HlcTimestamp

Cut-over timestamp: all legacy epochs sort before it, all new HLC timestamps sort at or after it.

Implementations

impl MigrationWatermark

pub const FORMAT_LEGACY_EPOCH: u32 = 1

mvcc_format_version while row versions carry StoredVersionStamp::LegacyEpoch.

pub const FORMAT_HLC: u32 = 2

mvcc_format_version once row versions carry StoredVersionStamp::Hlc.

pub fn cmp_stamps(a: &StoredVersionStamp, b: &StoredVersionStamp) -> Ordering

Total order over stored version stamps during migration: legacy epochs order numerically among themselves, every legacy epoch sorts before every HLC timestamp, and HLC timestamps keep their natural order.

pub fn cmp_stamp_to_watermark(&self, stamp: &StoredVersionStamp) -> Ordering

How a stamp orders against the watermark: every legacy epoch sorts before it; HLC timestamps sort at or after it (a pre-watermark HLC timestamp cannot occur once the watermark is enforced, so it clamps to Ordering::Equal).

Trait Implementations

impl Clone for MigrationWatermark

fn clone(&self) -> MigrationWatermark

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for MigrationWatermark

impl Debug for MigrationWatermark

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for MigrationWatermark

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Eq for MigrationWatermark

impl Hash for MigrationWatermark

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for MigrationWatermark

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for MigrationWatermark

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for MigrationWatermark