Struct FourTables 

pub struct FourTables { /* private fields */ }

Four Arrow IPC sections — oid, byte extent, type, size — joined by row ordinal.

This is git’s own shape: .idx, .rev and the missing type/size files, each an independent artifact. A lookup resolves the oid to an ordinal and then indexes three further sections at that ordinal.

The name counts sections, which is this arm’s whole difference from OneTableFourColumns. It carries five payload columns: delta_base joined the schema afterwards and shares the extent section, for the reason given on [extent_schema].

Implementations

impl FourTables

pub fn ipc_section_lens(&self) -> [usize; 4]

Section order: oid, extent, type, size.

pub fn oid_column(&self) -> &FixedSizeBinaryArray

The oid column, straight out of its own section — proof that “four tables” still gives a contiguous scannable column.

pub fn column_is_inside_ipc(&self) -> bool

Every column’s bytes lie inside the section they were decoded from.

Trait Implementations

impl ObjectIndex for FourTables

fn build(entries: &[IndexEntry]) -> Result<Self>

fn lookup(&self, oid: &[u8]) -> Option<IndexRow>

Resolve one oid. None for an absent oid and for an oid of the wrong width.

fn lookup_batch(&self, oids: &[&[u8]]) -> Vec<Option<IndexRow>>

The batch path, and the one that matters: have negotiation sends up to 1000 oids at a time, the push connectivity check sends thousands. Positional — out[i] answers oids[i].

fn ordinals_batch(&self, oids: &[&[u8]]) -> Vec<Option<u32>>

oid → ordinal and stop. No payload column is touched at all.

fn extents_batch(&self, oids: &[&[u8]]) -> Vec<Option<(u64, u64)>>

The partial-row access pattern: byte extent only, two of the five facts. This is extents(&[oid]), what the wire path actually asks for when it is about to copy bytes out of a pack.

fn sum_uncompressed(&self) -> u64

Full column scan: total uncompressed bytes over every object. The quota gate. Reads one 8-byte fact per row and nothing else.

fn count_type(&self, t: ObjType) -> usize

Full column scan with a predicate: how many objects of this type. Reads one byte per row and nothing else — the most column-shaped query there is, and the one a row-packed layout should lose worst.

fn name(&self) -> &'static str

fn len(&self) -> usize

fn ipc_bytes(&self) -> usize

Total bytes of Arrow IPC this index holds resident. Four sections or one, this counts the same payload, so it is comparable across arms.

fn resident_bytes(&self) -> usize

IPC bytes plus the stree oid section — everything the index keeps alive, excluding the handful of Arc’d schema/metadata allocations.

fn is_empty(&self) -> bool