Enum AccessPath 

#[non_exhaustive]
pub enum AccessPath {
    FullScan,
    PartitionLookup,
    MultiPartitionLookup,
    ClusteringSlice,
    MetadataPartitionLookup,
    StreamingPartitionLookup,
    FallbackFullScan {
        reason: FallbackReason,
    },
}

The access path a SELECT surface selected for a single SSTable-scan step.

This is the public, testable signal. Variant names are a shared contract with #958 (work counters) and #962 (fast-path unification); do not rename without updating those consumers and docs/access-paths.md.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

FullScan

Every SSTable for the table is scanned and rows are filtered in memory. This is the honest baseline when no usable restriction is present.

PartitionLookup

A single, fully-constrained partition (WHERE pk = ?) is served by a partition-targeted lookup that prunes SSTables (bloom/BTI presence) before scanning. Materializing path (#949 fast path).

MultiPartitionLookup

Several fully-constrained partitions (WHERE pk IN (...) / token fan-out) are served by repeated partition-targeted lookups. Reserved for #955; not yet produced by any surface, but named here so #955 can consume it.

ClusteringSlice

A partition is targeted and a clustering-key predicate (WHERE pk = ? AND ck </>/= ?) prunes rows within the partition. Reserved for #954; not yet produced by any surface.

MetadataPartitionLookup

The WRITETIME/TTL metadata-projection path resolved a single fully constrained partition via a targeted lookup (#962). The WHERE pk IN (...) metadata fan-out reports Self::MultiPartitionLookup instead (#1916).

StreamingPartitionLookup

The streaming SELECT path served a single fully-constrained partition via a partition-targeted lookup (the streaming analogue of Self::PartitionLookup).

FallbackFullScan

A targeted path was not selected and execution fell back to a full scan. The reason is from the documented closed set FallbackReason, so an accidental fallback cannot look like a targeted success.

Fields

reason: FallbackReason

Why the targeted path was not taken.

Implementations

impl AccessPath

pub fn is_full_scan(&self) -> bool

True if this path scans the whole table (full scan or any fallback to one).

Tests use this to assert “this query did NOT do a full scan” without matching every fallback reason.

pub fn is_targeted(&self) -> bool

True if this path targeted one or more specific partitions rather than scanning the whole table.

pub fn label(&self) -> &'static str

A stable, lowercase label suitable for EXPLAIN-style output and JSON.

Trait Implementations

impl Clone for AccessPath

fn clone(&self) -> AccessPath

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for AccessPath

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for AccessPath

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Display for AccessPath

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

Formats the value using the given formatter.

impl Eq for AccessPath

impl PartialEq for AccessPath

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for AccessPath

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

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for AccessPath