Struct Memtable 

pub struct Memtable { /* private fields */ }

Bε-tree-backed memtable, ordered by (RowId, Epoch). A drop-in replacement for the prototype skip list: the same MVCC semantics with lower write amplification (buffered messages flush to children in bulk).

Implementations

impl Memtable

pub fn new() -> Self

pub fn upsert(&mut self, row: Row)

Append a row version (keyed by (row_id, committed_epoch)). Versions are never overwritten; the newest visible one wins at read time.

pub fn tombstone(&mut self, row_id: RowId, epoch: Epoch)

Append a tombstone version for row_id at epoch. The tombstone copies the columns from the newest live version so that engine-level HOT cleanup can recover the primary-key value during WAL replay.

pub fn get(&self, row_id: RowId, snapshot_epoch: Epoch) -> Option<Row>

Read the row at row_id visible to snapshot: the newest version with epoch <= snapshot. Returns None if that version is a tombstone (or no such version exists).

pub fn get_version( &self, row_id: RowId, snapshot_epoch: Epoch, ) -> Option<(Epoch, Row)>

Newest version of row_id with epoch <= snapshot, including tombstones (as a Row with deleted=true). Used by the engine to merge versions across the memtable and sorted runs.

pub fn len(&self) -> usize

Number of stored versions.

pub fn is_empty(&self) -> bool

pub fn approx_bytes(&self) -> u64

pub fn visible_rows(&self, snapshot_epoch: Epoch) -> Vec<Row>

Visible rows at snapshot, deduplicated to the newest version per RowId (tombstones drop their row). Returned in ascending RowId order.

pub fn visible_versions(&self, snapshot_epoch: Epoch) -> Vec<Row>

Newest visible version per RowId at snapshot, including tombstones (as Rows with deleted=true). Used by the engine to merge versions across the memtable and sorted runs.

pub fn drain_sorted(&mut self) -> Vec<Row>

Drain all versions (for a memtable-to-run flush). Returns them in ascending (RowId, Epoch) order.

Trait Implementations

impl Default for Memtable

fn default() -> Self

Returns the “default value” for a type.