Struct RowId 

#[repr(transparent)]
pub struct RowId(pub u64);

v7.37.15 (Phase C.1) — stable per-relation row identity.

Why a stable id, separate from the physical index

Pre-Phase-C a row was addressed by its physical index into Table::rows. That index is invalidated the moment a delete / vacuum compacts the survivor vec — every surviving row after the hole shifts down. Physical indices therefore cannot serve as:

1. a row-lock key (Phase C.4: (RelId, RowId) must survive concurrent compaction while a lock is held),
2. a HOT-chain pointer (Phase D: chain head → new version must not dangle after vacuum),
3. a WAL redo identity (Epic W: RowChange UPDATE/DELETE must name the row by a key that survives replay, not a slot that shifted — closing the position-fragility caveat on the RowChange doc).

RowId is per-relation, monotonic, and never reused. It lives in Table::rowids: PersistentVec<RowId> parallel to rows / headers, so rowids[i] is the stable id of the row physically at slot i. Compaction rebuilds all three vecs together, so the id travels with the row while the slot shifts.

Phase C.1 introduces the id additively (allocated + kept lock-step, but indices still address by physical slot); later phases migrate index locators, the lock table, and the WAL to address by RowId.

u64, never wraps (same rationale as xmin/xmax). Starts at 1 per relation; 0 is reserved as an “unassigned” sentinel.

Tuple Fields

0: u64

Implementations

impl RowId

pub const UNASSIGNED: RowId

The “unassigned” sentinel. A real appended row never gets 0; the per-relation allocator starts at 1.

Trait Implementations

impl Clone for RowId

fn clone(&self) -> RowId

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for RowId

impl Debug for RowId

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

Formats the value using the given formatter.

impl Eq for RowId

impl Hash for RowId

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 RowId

fn cmp(&self, other: &RowId) -> 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 RowId

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

Equality operator ==.

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

Inequality operator !=.

impl PartialOrd for RowId

fn partial_cmp(&self, other: &RowId) -> 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 StructuralPartialEq for RowId