Method lookup_memtable_row_by_pk

nodedb-columnar/src/mutation/write.rs:157–163

Look up the current row for a PK in the memtable, if present. Returns `None` if the PK is not in the index, or if the PK points to a flushed segment (callers needing cross-segment lookup must go through a segment reader separately). This is the fast path used by `ON CONFLICT DO UPDATE` to read the would-be-merged row when the duplicate hits the memtable — the common case under back-to-back insert

(&self, pk_bytes: &[u8])

    /// when the duplicate hits the memtable — the common case under
    /// back-to-back inserts.
    pub fn lookup_memtable_row_by_pk(&self, pk_bytes: &[u8]) -> Option<Vec<Value>> {
        let loc = self.pk_index.get(pk_bytes).copied()?;
        if loc.segment_id != self.memtable_segment_id {
            return None;
        }
        self.memtable.get_row(loc.row_index as usize)
    }

    /// Delete a row by PK value. Returns WAL record to persist.
    ///