Struct Lsn

pub struct Lsn {
    vlf_id: u32,
    block_id: u32,
    record_id: u16,
}

This type is used to represent the progress of each SQL Server instance in the ingestion dataflow.

A SQL Server LSN is a three part “number” that provides a total order to all transations within a database. Interally we don’t really care what these parts mean, but they are:

1. A Virtual Log File (VLF) sequence number, bytes [0, 4)
2. Log block number, bytes [4, 8)
3. Log record number, bytes [8, 10)

For more info on log sequence numbers in SQL Server see: https://learn.microsoft.com/en-us/sql/relational-databases/sql-server-transaction-log-architecture-and-management-guide?view=sql-server-ver16#Logical_Arch

Note: The derived impl of PartialOrd and Ord relies on the field ordering so do not change it.

Fields

vlf_id: u32

Virtual Log File sequence number.

block_id: u32

Log block number.

record_id: u16

Log record number.

Implementations

impl Lsn

const SIZE: usize = 10usize

pub fn try_from_bytes(bytes: &[u8]) -> Result<Self, String>

Interpret the provided bytes as an Lsn.

pub fn as_bytes(&self) -> [u8; 10]

Return the underlying byte slice for this Lsn.

pub fn increment(self) -> Lsn

Increment this Lsn.

The returned Lsn may not exist upstream yet, but it’s guaranteed to sort greater than self.

pub fn abbreviate(&self) -> u64

Drops the record_id portion of the Lsn so we can fit an “abbreviation” of this Lsn into a u64, without losing the total order.

Trait Implementations

impl Arbitrary for Lsn

type Parameters = (<u32 as Arbitrary>::Parameters, <u32 as Arbitrary>::Parameters, <u16 as Arbitrary>::Parameters)

The type of parameters that arbitrary_with accepts for configuration of the generated Strategy. Parameters must implement Default.

type Strategy = Map<(<u32 as Arbitrary>::Strategy, <u32 as Arbitrary>::Strategy, <u16 as Arbitrary>::Strategy), fn(_: (u32, u32, u16)) -> Lsn>

The type of Strategy used to generate values of type Self.

fn arbitrary_with(_top: Self::Parameters) -> Self::Strategy

Generates a Strategy for producing arbitrary values of type the implementing type (Self). The strategy is passed the arguments given in args.

fn arbitrary() -> Self::Strategy

Generates a Strategy for producing arbitrary values of type the implementing type (Self).

impl Clone for Lsn

fn clone(&self) -> Lsn

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Columnation for Lsn

type InnerRegion = CopyRegion<Lsn>

The type of region capable of absorbing allocations owned by the Self type. Note: not allocations of Self, but of the things that it owns.

impl Debug for Lsn

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

Formats the value using the given formatter.

impl Default for Lsn

fn default() -> Lsn

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for Lsn

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Display for Lsn

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

Formats the value using the given formatter.

impl Hash for Lsn

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 Ord for Lsn

fn cmp(&self, other: &Lsn) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for Lsn

fn eq(&self, other: &Lsn) -> 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 PartialOrd for Lsn

fn partial_cmp(&self, other: &Lsn) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

Tests less than or equal to (for self and other) and is used by the <= operator.

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

Tests greater than (for self and other) and is used by the > operator.

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

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl PartialOrder for Lsn

fn less_equal(&self, other: &Self) -> bool

Returns true iff one element is less than or equal to the other.

fn less_than(&self, other: &Self) -> bool

Returns true iff one element is strictly less than the other.

impl PathSummary<Lsn> for ()

fn results_in(&self, src: &Lsn) -> Option<Lsn>

Advances a timestamp according to the timestamp actions on the path.

fn followed_by(&self, _other: &Self) -> Option<Self>

Composes this path summary with another path summary.

impl Refines<()> for Lsn

fn to_inner(_other: ()) -> Self

Converts the outer timestamp to an inner timestamp.

fn to_outer(self)

Converts the inner timestamp to an outer timestamp.

fn summarize(_path: <Self as Timestamp>::Summary)

Summarizes an inner path summary as an outer path summary.

impl Serialize for Lsn

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

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl Timestamp for Lsn

type Summary = ()

A type summarizing action on a timestamp along a dataflow path.

fn minimum() -> Self

A minimum value suitable as a default.

impl TryFrom<&[u8]> for Lsn

type Error = String

The type returned in the event of a conversion error.

fn try_from(value: &[u8]) -> Result<Self, Self::Error>

Performs the conversion.

impl Copy for Lsn

impl Eq for Lsn

impl StructuralPartialEq for Lsn

impl TotalOrder for Lsn