Minor refactor of the cardinality aggregation. (#3120)

The Str path and the non string path are very different.
This PR isolates them as different segment aggregation collector.

Co-authored-by: Paul Masurel <paul.masurel@datadoghq.com>
This commit is contained in:
Paul Masurel
2026-09-22 10:47:49 +02:00
committed by GitHub
co-authored by Paul Masurel
parent b91a405ee9
commit 507e1760aa
6 changed files with 1607 additions and 1443 deletions
+3 -36
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@@ -22,9 +22,8 @@ use crate::aggregation::bucket::{
use crate::aggregation::metric::{
build_segment_stats_collector, AverageAggregation, CardinalityAggReqData,
CardinalityAggregationReq, CountAggregation, ExtendedStatsAggregation, MaxAggregation,
MetricAggReqData, MinAggregation, SegmentCardinalityCollector, SegmentExtendedStatsCollector,
SegmentPercentilesCollector, StatsAggregation, StatsType, SumAggregation, TermOrdSet,
TopHitsAggReqData, TopHitsSegmentCollector, BITSET_MAX_TERM_ORD,
MetricAggReqData, MinAggregation, SegmentExtendedStatsCollector, SegmentPercentilesCollector,
StatsAggregation, StatsType, SumAggregation, TopHitsAggReqData, TopHitsSegmentCollector,
};
use crate::aggregation::segment_agg_result::{
GenericSegmentAggregationResultsCollector, SegmentAggregationCollector,
@@ -286,39 +285,7 @@ pub(crate) fn build_segment_agg_collector(
Ok(Box::new(TermMissingAgg::new(req, node)?))
}
AggKind::Cardinality => {
let req_data = req.get_cardinality_req_data(node.idx_in_req_data);
// For str columns, choose the per-bucket entries representation
// based on the segment's column.max_value():
// * small (< BITSET_MAX_TERM_ORD): `BitSet`, pre-allocated, no promotion machinery.
// * large: `TermOrdSet` (sparse FxHashSet that promotes to a paged bitset).
// For non-str columns the `entries` field is unused (values go
// straight into the HLL sketch); we still pick `TermOrdSet`
// because its empty Sparse(FxHashSet) costs nothing.
let is_str = req_data.column_type == ColumnType::Str;
let max_term_ord_inclusive = if is_str {
req_data.accessor.max_value()
} else {
0
};
let collector: Box<dyn SegmentAggregationCollector> =
if is_str && max_term_ord_inclusive < BITSET_MAX_TERM_ORD {
Box::new(SegmentCardinalityCollector::<BitSet>::from_req(
req_data.column_type,
node.idx_in_req_data,
req_data.accessor.clone(),
req_data.missing_value_for_accessor,
max_term_ord_inclusive,
))
} else {
Box::new(SegmentCardinalityCollector::<TermOrdSet>::from_req(
req_data.column_type,
node.idx_in_req_data,
req_data.accessor.clone(),
req_data.missing_value_for_accessor,
max_term_ord_inclusive,
))
};
Ok(collector)
crate::aggregation::metric::build_segment_cardinality_collector(req, node)
}
AggKind::StatsKind(stats_type) => {
let req_data = &mut req.per_request.stats_metric_req_data[node.idx_in_req_data];
File diff suppressed because it is too large Load Diff
+609
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@@ -0,0 +1,609 @@
//! Cardinality aggregation.
//!
//! * [`str_collector`] holds the `ColumnType::Str` segment collector, which accumulates term
//! ordinals and resolves them to HLL coupons at finalization.
//! * [`numeric_collector`] holds the segment collector for every other column type, which feeds
//! the HLL sketch directly during collection.
//!
//! Both segment collectors converge on the same
//! [`IntermediateMetricResult::Cardinality`] payload, so results coming from a
//! str column and from a numeric column (e.g. a JSON path that resolves to
//! both) merge through the single [`CardinalityCollector::merge_fruits`]
//! implementation here.
mod numeric_collector;
mod str_collector;
mod term_ord_accumulator;
use std::hash::Hash;
use columnar::{Column, ColumnType, StrColumn};
use common::BitSet;
use datasketches::hll::{Coupon, HllSketch, HllType, HllUnion};
pub(crate) use numeric_collector::SegmentNumericCardinalityCollector;
use serde::{Deserialize, Deserializer, Serialize, Serializer};
pub(crate) use str_collector::SegmentStrCardinalityCollector;
pub(crate) use term_ord_accumulator::{TermOrdSet, BITSET_MAX_TERM_ORD};
use crate::aggregation::agg_data::{AggRefNode, AggregationsSegmentCtx};
use crate::aggregation::segment_agg_result::SegmentAggregationCollector;
use crate::aggregation::*;
/// Log2 of the number of registers for the HLL sketch.
/// 2^11 = 2048 registers, giving ~2.3% relative error and ~1KB per sketch (Hll4).
const LG_K: u8 = 11;
/// # Cardinality
///
/// The cardinality aggregation allows for computing an estimate
/// of the number of different values in a data set based on the
/// Apache DataSketches HyperLogLog algorithm. This is particularly useful for
/// understanding the uniqueness of values in a large dataset where counting
/// each unique value individually would be computationally expensive.
///
/// For example, you might use a cardinality aggregation to estimate the number
/// of unique visitors to a website by aggregating on a field that contains
/// user IDs or session IDs.
///
/// To use the cardinality aggregation, you'll need to provide a field to
/// aggregate on. The following example demonstrates a request for the cardinality
/// of the "user_id" field:
///
/// ```JSON
/// {
/// "cardinality": {
/// "field": "user_id"
/// }
/// }
/// ```
///
/// This request will return an estimate of the number of unique values in the
/// "user_id" field.
///
/// ## Missing Values
///
/// The `missing` parameter defines how documents that are missing a value should be treated.
/// By default, documents without a value for the specified field are ignored. However, you can
/// specify a default value for these documents using the `missing` parameter. This can be useful
/// when you want to include documents with missing values in the aggregation.
///
/// For example, the following request treats documents with missing values in the "user_id"
/// field as if they had a value of "unknown":
///
/// ```JSON
/// {
/// "cardinality": {
/// "field": "user_id",
/// "missing": "unknown"
/// }
/// }
/// ```
///
/// # Estimation Accuracy
///
/// The cardinality aggregation provides an approximate count, which is usually
/// accurate within a small error range. This trade-off allows for efficient
/// computation even on very large datasets.
#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
pub struct CardinalityAggregationReq {
/// The field name to compute the percentiles on.
pub field: String,
/// The missing parameter defines how documents that are missing a value should be treated.
/// By default they will be ignored but it is also possible to treat them as if they had a
/// value. Examples in JSON format:
/// { "field": "my_numbers", "missing": "10.0" }
#[serde(skip_serializing_if = "Option::is_none", default)]
pub missing: Option<Key>,
}
/// Contains all information required by the segment cardinality collectors to perform the
/// cardinality aggregation on a segment.
pub(crate) struct CardinalityAggReqData {
/// The column accessor to access the fast field values.
pub(crate) accessor: Column<u64>,
/// The column_type of the field.
pub(crate) column_type: ColumnType,
/// The string dictionary column if the field is of type string.
pub(crate) str_dict_column: Option<StrColumn>,
/// The missing value normalized to the internal u64 representation of the field type.
pub(crate) missing_value_for_accessor: Option<u64>,
/// The name of the aggregation.
pub(crate) name: String,
/// The aggregation request.
pub(crate) req: CardinalityAggregationReq,
}
impl CardinalityAggReqData {
/// Estimate the memory consumption of this struct in bytes.
pub fn get_memory_consumption(&self) -> usize {
std::mem::size_of::<Self>()
}
}
impl CardinalityAggregationReq {
/// Creates a new [`CardinalityAggregationReq`] instance from a field name.
pub fn from_field_name(field_name: String) -> Self {
Self {
field: field_name,
missing: None,
}
}
/// Returns the field name the aggregation is computed on.
pub fn field_name(&self) -> &str {
&self.field
}
}
#[derive(Clone, Debug)]
/// The cardinality collector used during segment collection and for merging results.
/// Uses Apache DataSketches HLL (lg_k=11, Hll4) for compact binary serialization
/// and cross-language compatibility (e.g. Java `datasketches` library).
pub struct CardinalityCollector {
sketch: HllSketch,
/// Salt derived from `ColumnType`, used to differentiate values of different column types
/// that map to the same u64 (e.g. bool `false` = 0 vs i64 `0`).
/// Not serialized — only needed during insertion, not after sketch registers are populated.
salt: u8,
}
impl Default for CardinalityCollector {
fn default() -> Self {
Self::new(0)
}
}
impl PartialEq for CardinalityCollector {
fn eq(&self, _other: &Self) -> bool {
false
}
}
impl Serialize for CardinalityCollector {
fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
let bytes = self.sketch.serialize();
serializer.serialize_bytes(&bytes)
}
}
impl<'de> Deserialize<'de> for CardinalityCollector {
fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
let bytes: Vec<u8> = Deserialize::deserialize(deserializer)?;
let sketch = HllSketch::deserialize(&bytes).map_err(serde::de::Error::custom)?;
Ok(Self { sketch, salt: 0 })
}
}
impl CardinalityCollector {
fn new(salt: u8) -> Self {
Self {
sketch: HllSketch::new(LG_K, HllType::Hll8),
salt,
}
}
/// Insert a value into the HLL sketch, salted by the column type.
/// The salt ensures that identical u64 values from different column types
/// (e.g. bool `false` vs i64 `0`) are counted as distinct.
fn insert(&mut self, value: impl Hash) {
self.sketch.update((self.salt, value));
}
fn insert_coupon(&mut self, coupon: Coupon) {
self.sketch.update_with_coupon(coupon);
}
/// Compute the final cardinality estimate.
pub fn finalize(self) -> Option<f64> {
Some(self.sketch.estimate().trunc())
}
/// Serialize the HLL sketch to its compact binary representation.
/// The format is cross-language compatible with Apache DataSketches (Java, C++, Python).
pub fn to_sketch_bytes(&self) -> Vec<u8> {
self.sketch.serialize()
}
pub(crate) fn merge_fruits(&mut self, right: CardinalityCollector) -> crate::Result<()> {
let mut union = HllUnion::new(LG_K);
union.update(&self.sketch);
union.update(&right.sketch);
self.sketch = union.to_sketch(HllType::Hll8);
Ok(())
}
}
/// Builds the segment collector for a cardinality aggregation.
///
/// str and non-str columns use two entirely different collectors: str
/// accumulates term ordinals and resolves them into HLL coupons at
/// finalization, non-str feeds the HLL sketch directly. Both produce the same
/// [`IntermediateMetricResult::Cardinality`], so they merge uniformly.
pub(crate) fn build_segment_cardinality_collector(
req: &mut AggregationsSegmentCtx,
node: &AggRefNode,
) -> crate::Result<Box<dyn SegmentAggregationCollector>> {
let req_data = req.get_cardinality_req_data(node.idx_in_req_data);
if req_data.column_type != ColumnType::Str {
return Ok(Box::new(SegmentNumericCardinalityCollector::from_req(
req_data.column_type,
node.idx_in_req_data,
req_data.accessor.clone(),
req_data.missing_value_for_accessor,
)?));
}
// For str columns, we need to collect the set of term ordinals encounterred.
// We choose a different representation depending on the number of maximum
// number of terms.
// * small (< BITSET_MAX_TERM_ORD): `BitSet`, pre-allocated.
// * large: `TermOrdSet` (sparse HashSet that promotes to a paged bitset).
let max_term_ord_inclusive = req_data.accessor.max_value();
if max_term_ord_inclusive < BITSET_MAX_TERM_ORD {
Ok(Box::new(
SegmentStrCardinalityCollector::<BitSet>::from_req(
node.idx_in_req_data,
req_data.accessor.clone(),
req_data.missing_value_for_accessor,
max_term_ord_inclusive,
),
))
} else {
Ok(Box::new(
SegmentStrCardinalityCollector::<TermOrdSet>::from_req(
node.idx_in_req_data,
req_data.accessor.clone(),
req_data.missing_value_for_accessor,
max_term_ord_inclusive,
),
))
}
}
#[cfg(test)]
mod tests {
use columnar::MonotonicallyMappableToU64;
use crate::aggregation::agg_req::Aggregations;
use crate::aggregation::tests::{exec_request, get_test_index_from_terms};
use crate::schema::{Schema, FAST, STRING};
use crate::Index;
#[test]
fn cardinality_aggregation_test_empty_index() -> crate::Result<()> {
let values = vec![];
let index = get_test_index_from_terms(false, &values)?;
let agg_req: Aggregations = serde_json::from_value(json!({
"cardinality": {
"cardinality": {
"field": "string_id",
}
},
}))
.unwrap();
let res = exec_request(agg_req, &index)?;
assert_eq!(res["cardinality"]["value"], 0.0);
Ok(())
}
#[test]
fn cardinality_aggregation_test_single_segment() -> crate::Result<()> {
cardinality_aggregation_test_merge_segment(true)
}
#[test]
fn cardinality_aggregation_test() -> crate::Result<()> {
cardinality_aggregation_test_merge_segment(false)
}
fn cardinality_aggregation_test_merge_segment(merge_segments: bool) -> crate::Result<()> {
let segment_and_terms = vec![
vec!["terma"],
vec!["termb"],
vec!["termc"],
vec!["terma"],
vec!["terma"],
vec!["terma"],
vec!["termb"],
vec!["terma"],
];
let index = get_test_index_from_terms(merge_segments, &segment_and_terms)?;
let agg_req: Aggregations = serde_json::from_value(json!({
"cardinality": {
"cardinality": {
"field": "string_id",
}
},
}))
.unwrap();
let res = exec_request(agg_req, &index)?;
assert_eq!(res["cardinality"]["value"], 3.0);
Ok(())
}
#[test]
fn cardinality_aggregation_bytes_excluded_from_accessors() -> crate::Result<()> {
// `Bytes` columns are opened as raw per-segment dictionary ordinals (like `Str`), but
// unlike `Str`, cardinality has no dictionary-resolution path for them: it would hash
// the raw ordinal directly, which are segment dependant. Ignore bytes values instead of
// counting them wrong.
let mut schema_builder = Schema::builder();
let field = schema_builder.add_bytes_field("raw", FAST);
let index = Index::create_in_ram(schema_builder.build());
{
let mut writer = index.writer_for_tests()?;
writer.add_document(doc!(field => vec![1u8]))?;
writer.add_document(doc!(field => vec![2u8]))?;
writer.commit()?;
writer.add_document(doc!(field => vec![3u8]))?;
writer.add_document(doc!(field => vec![4u8]))?;
writer.commit()?;
}
let agg_req: Aggregations = serde_json::from_value(json!({
"cardinality": {
"cardinality": {
"field": "raw"
},
}
}))
.unwrap();
let res = exec_request(agg_req, &index)?;
assert_eq!(res["cardinality"]["value"], 0.0);
Ok(())
}
#[test]
fn cardinality_aggregation_json() -> crate::Result<()> {
let mut schema_builder = Schema::builder();
let field = schema_builder.add_json_field("json", FAST);
let index = Index::create_in_ram(schema_builder.build());
{
let mut writer = index.writer_for_tests()?;
writer.add_document(doc!(field => json!({"value": false})))?;
writer.add_document(doc!(field => json!({"value": true})))?;
writer.add_document(doc!(field => json!({"value": i64::from_u64(0u64)})))?;
writer.add_document(doc!(field => json!({"value": i64::from_u64(1u64)})))?;
writer.commit()?;
}
let agg_req: Aggregations = serde_json::from_value(json!({
"cardinality": {
"cardinality": {
"field": "json.value"
},
}
}))
.unwrap();
let res = exec_request(agg_req, &index)?;
assert_eq!(res["cardinality"]["value"], 4.0);
Ok(())
}
/// A JSON path that resolves to both a Str column and a numeric column
/// produces two collector instances per segment — one with `Str` buckets
/// and one with `Numeric` buckets. Their `IntermediateMetricResult`s must
/// merge into the union cardinality.
#[test]
fn cardinality_aggregation_json_str_and_numeric() -> crate::Result<()> {
let mut schema_builder = Schema::builder();
let field = schema_builder.add_json_field("json", FAST);
let index = Index::create_in_ram(schema_builder.build());
{
let mut writer = index.writer_for_tests()?;
writer.add_document(doc!(field => json!({"value": "hello"})))?;
writer.add_document(doc!(field => json!({"value": "world"})))?;
writer.add_document(doc!(field => json!({"value": "hello"})))?; // dup str
writer.add_document(doc!(field => json!({"value": i64::from_u64(7u64)})))?;
writer.add_document(doc!(field => json!({"value": i64::from_u64(42u64)})))?;
writer.add_document(doc!(field => json!({"value": i64::from_u64(7u64)})))?; // dup num
writer.commit()?;
}
let agg_req: Aggregations = serde_json::from_value(json!({
"cardinality": {
"cardinality": {
"field": "json.value"
},
}
}))
.unwrap();
let res = exec_request(agg_req, &index)?;
// 4 distinct values: "hello", "world", 7, 42.
assert_eq!(res["cardinality"]["value"], 4.0);
Ok(())
}
#[test]
fn cardinality_collector_serde_roundtrip() {
use super::CardinalityCollector;
let mut collector = CardinalityCollector::default();
collector.insert("hello");
collector.insert("world");
collector.insert("hello"); // duplicate
let serialized = serde_json::to_vec(&collector).unwrap();
let deserialized: CardinalityCollector = serde_json::from_slice(&serialized).unwrap();
let original_estimate = collector.finalize().unwrap();
let roundtrip_estimate = deserialized.finalize().unwrap();
assert_eq!(original_estimate, roundtrip_estimate);
assert_eq!(original_estimate, 2.0);
}
#[test]
fn cardinality_collector_merge() {
use super::CardinalityCollector;
let mut left = CardinalityCollector::default();
left.insert("a");
left.insert("b");
let mut right = CardinalityCollector::default();
right.insert("b");
right.insert("c");
left.merge_fruits(right).unwrap();
let estimate = left.finalize().unwrap();
assert_eq!(estimate, 3.0);
}
/// Verifies that merging two small sketches (both in List/Set coupon mode)
/// produces an exact result — i.e. the HllUnion does not unnecessarily
/// promote to the full HLL array when the combined cardinality is small.
#[test]
fn cardinality_collector_merge_stays_exact_for_small_sets() {
use super::CardinalityCollector;
let mut left = CardinalityCollector::default();
for i in 0u64..50 {
left.insert(i);
}
let mut right = CardinalityCollector::default();
for i in 30u64..100 {
right.insert(i);
}
left.merge_fruits(right).unwrap();
let estimate = left.finalize().unwrap();
// 100 distinct values (0..100). Both sketches are in Set mode (< 192 coupons),
// so the union should stay in coupon mode and give an exact count.
assert_eq!(estimate, 100.0);
}
#[test]
fn cardinality_collector_serialize_deserialize_binary() {
use datasketches::hll::HllSketch;
use super::CardinalityCollector;
let mut collector = CardinalityCollector::default();
collector.insert("apple");
collector.insert("banana");
collector.insert("cherry");
let bytes = collector.to_sketch_bytes();
let deserialized = HllSketch::deserialize(&bytes).unwrap();
assert!((deserialized.estimate() - 3.0).abs() < 0.01);
}
/// Tests that the `missing` parameter correctly counts a single empty document
/// for both u64 and str columns.
#[test]
fn cardinality_aggregation_missing_value_single_empty_doc() {
let mut schema_builder = Schema::builder();
let id_field = schema_builder.add_u64_field("id", FAST);
let name_field = schema_builder.add_text_field("name", STRING | FAST);
let index = Index::create_in_ram(schema_builder.build());
let mut writer = index.writer_for_tests().unwrap();
writer
.add_document(doc!(id_field=>1u64,name_field=>"some_name"))
.unwrap();
writer.add_document(doc!()).unwrap();
writer.commit().unwrap();
{
// int colum with missing value non redundant
let agg_req: Aggregations = serde_json::from_value(json!({
"cardinality": {
"cardinality": {
"field": "id",
"missing": 42u64
},
}
}))
.unwrap();
let res = exec_request(agg_req, &index).unwrap();
assert_eq!(res["cardinality"]["value"], 2.0);
}
{
// int colum with missing value redundant
let agg_req: Aggregations = serde_json::from_value(json!({
"cardinality": {
"cardinality": {
"field": "id",
"missing": 1u64
},
}
}))
.unwrap();
let res = exec_request(agg_req, &index).unwrap();
assert_eq!(res["cardinality"]["value"], 1.0);
}
{
// str colum with missing value non redundant
// With more than one segment, this is not well handled.
let agg_req: Aggregations = serde_json::from_value(json!({
"cardinality": {
"cardinality": {
"field": "name",
"missing": "other_name"
},
}
}))
.unwrap();
let res = exec_request(agg_req, &index).unwrap();
assert_eq!(res["cardinality"]["value"], 2.0);
}
{
// str colum with missing value redundant
let agg_req: Aggregations = serde_json::from_value(json!({
"cardinality": {
"cardinality": {
"field": "name",
"missing": "some_name"
},
}
}))
.unwrap();
let res = exec_request(agg_req, &index).unwrap();
assert_eq!(res["cardinality"]["value"], 1.0);
}
{
// str column with missing value with a number type.
let agg_req: Aggregations = serde_json::from_value(json!({
"cardinality": {
"cardinality": {
"field": "name",
"missing": 3,
},
}
}))
.unwrap();
let res = exec_request(agg_req, &index).unwrap();
assert_eq!(res["cardinality"]["value"], 2.0);
}
}
#[test]
fn cardinality_collector_salt_differentiates_types() {
use super::CardinalityCollector;
// Without salt, same u64 value from different column types would collide
let mut collector_bool = CardinalityCollector::new(5); // e.g. ColumnType::Bool
collector_bool.insert(0u64); // false
collector_bool.insert(1u64); // true
let mut collector_i64 = CardinalityCollector::new(2); // e.g. ColumnType::I64
collector_i64.insert(0u64);
collector_i64.insert(1u64);
// Merge them
collector_bool.merge_fruits(collector_i64).unwrap();
let estimate = collector_bool.finalize().unwrap();
// Should be 4 because salt makes (5, 0) != (2, 0) and (5, 1) != (2, 1)
assert_eq!(estimate, 4.0);
}
}
@@ -0,0 +1,255 @@
//! Segment collector for `cardinality` over any non-str column
//! (numeric, bool, date, IpAddr).
//!
//! Unlike the str case there is no dictionary to resolve, so values go
//! straight into a per-bucket HLL sketch during collection. The produced
//! [`CardinalityCollector`] is the same type the str collector produces, so
//! intermediate merging stays in the parent module.
use std::fmt::Debug;
use std::sync::Arc;
use columnar::column_values::CompactSpaceU64Accessor;
use columnar::{Column, ColumnType};
use super::CardinalityCollector;
use crate::aggregation::agg_data::AggregationsSegmentCtx;
use crate::aggregation::intermediate_agg_result::{
IntermediateAggregationResult, IntermediateAggregationResults, IntermediateMetricResult,
};
use crate::aggregation::segment_agg_result::SegmentAggregationCollector;
use crate::aggregation::*;
use crate::TantivyError;
/// Segment collector for `cardinality` over any non-str column
/// (numeric, bool, date, IpAddr).
///
/// Hidden contract: `column_type` must not be `ColumnType::Str`. Values are
/// inserted into the HLL sketch during collection, so the sketch of a bucket
/// is already complete when the bucket is finalized.
pub(crate) struct SegmentNumericCardinalityCollector {
/// Buckets are Some(_) until they get consumed by
/// `add_intermediate_aggregation_result`.
buckets: Vec<Option<CardinalityCollector>>,
accessor_idx: usize,
/// The column accessor to access the fast field values.
accessor: Column<u64>,
/// The column_type of the field.
column_type: ColumnType,
/// Set iff `column_type == ColumnType::IpAddr`. Resolved once at
/// construction: the raw column values are compact-space codes that must
/// be expanded to their u128 ip representation before hashing.
compact_space_accessor: Option<Arc<CompactSpaceU64Accessor>>,
/// The missing value normalized to the internal u64 representation of the field type.
missing_value_for_accessor: Option<u64>,
}
impl Debug for SegmentNumericCardinalityCollector {
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
f.debug_struct("SegmentNumericCardinalityCollector")
.field("column_type", &self.column_type)
.field(
"missing_value_for_accessor",
&self.missing_value_for_accessor,
)
.finish()
}
}
impl SegmentNumericCardinalityCollector {
pub fn from_req(
column_type: ColumnType,
accessor_idx: usize,
accessor: Column<u64>,
missing_value_for_accessor: Option<u64>,
) -> crate::Result<Self> {
assert_ne!(column_type, ColumnType::Str);
let compact_space_accessor = if column_type == ColumnType::IpAddr {
let compact_space_accessor = accessor
.values
.clone()
.downcast_arc::<CompactSpaceU64Accessor>()
.map_err(|_| {
TantivyError::AggregationError(
crate::aggregation::AggregationError::InternalError(
"Type mismatch: Could not downcast to CompactSpaceU64Accessor"
.to_string(),
),
)
})?;
Some(compact_space_accessor)
} else {
None
};
Ok(Self {
buckets: Vec::new(),
accessor_idx,
accessor,
column_type,
compact_space_accessor,
missing_value_for_accessor,
})
}
}
impl SegmentAggregationCollector for SegmentNumericCardinalityCollector {
fn add_intermediate_aggregation_result(
&mut self,
agg_data: &AggregationsSegmentCtx,
results: &mut IntermediateAggregationResults,
bucket_id: BucketId,
) -> crate::Result<()> {
self.prepare_max_bucket(bucket_id, agg_data)?;
let name = agg_data
.get_cardinality_req_data(self.accessor_idx)
.name
.to_string();
// take the bucket in buckets and replace it with a new empty one
let Some(cardinality) = self.buckets[bucket_id as usize].take() else {
return Err(crate::TantivyError::InternalError(
"the same bucket should not be finalized twice.".to_string(),
));
};
results.push(
name,
IntermediateAggregationResult::Metric(IntermediateMetricResult::Cardinality(
cardinality,
)),
)?;
Ok(())
}
fn collect(
&mut self,
parent_bucket_id: BucketId,
docs: &[crate::DocId],
agg_data: &mut AggregationsSegmentCtx,
) -> crate::Result<()> {
agg_data.column_block_accessor.fetch_block_with_missing(
docs,
&self.accessor,
self.missing_value_for_accessor,
);
let cardinality = self.buckets[parent_bucket_id as usize]
.as_mut()
.ok_or_else(|| {
crate::TantivyError::InternalError(
"collection should not happen after finalization".to_string(),
)
})?;
let col_block_accessor = &agg_data.column_block_accessor;
if let Some(compact_space_accessor) = self.compact_space_accessor.as_ref() {
for val in col_block_accessor.iter_vals() {
let val: u128 = compact_space_accessor.compact_to_u128(val as u32);
cardinality.insert(val);
}
} else {
for val in col_block_accessor.iter_vals() {
cardinality.insert(val);
}
}
Ok(())
}
fn prepare_max_bucket(
&mut self,
max_bucket: BucketId,
_agg_data: &AggregationsSegmentCtx,
) -> crate::Result<()> {
if max_bucket as usize >= self.buckets.len() {
let column_type = self.column_type;
self.buckets.resize_with(max_bucket as usize + 1, || {
Some(CardinalityCollector::new(column_type as u8))
});
}
Ok(())
}
fn compute_metric_value(
&self,
bucket_id: BucketId,
sub_agg_name: &str,
sub_agg_property: &str,
agg_data: &AggregationsSegmentCtx,
) -> Option<f64> {
let req_data = &agg_data.get_cardinality_req_data(self.accessor_idx);
if req_data.name != sub_agg_name || !sub_agg_property.is_empty() {
return None;
}
let cardinality = self.buckets.get(bucket_id as usize)?.as_ref()?;
Some(cardinality.sketch.estimate().trunc())
}
}
#[cfg(test)]
mod tests {
use std::net::IpAddr;
use std::str::FromStr;
use crate::aggregation::agg_req::Aggregations;
use crate::aggregation::tests::exec_request;
use crate::schema::{IntoIpv6Addr, Schema, FAST};
use crate::Index;
#[test]
fn cardinality_aggregation_u64() -> crate::Result<()> {
let mut schema_builder = Schema::builder();
let id_field = schema_builder.add_u64_field("id", FAST);
let index = Index::create_in_ram(schema_builder.build());
{
let mut writer = index.writer_for_tests()?;
writer.add_document(doc!(id_field => 1u64))?;
writer.add_document(doc!(id_field => 2u64))?;
writer.add_document(doc!(id_field => 3u64))?;
writer.add_document(doc!())?;
writer.commit()?;
}
let agg_req: Aggregations = serde_json::from_value(json!({
"cardinality": {
"cardinality": {
"field": "id",
"missing": 0u64
},
}
}))
.unwrap();
let res = exec_request(agg_req, &index)?;
assert_eq!(res["cardinality"]["value"], 4.0);
Ok(())
}
#[test]
fn cardinality_aggregation_ip_addr() -> crate::Result<()> {
let mut schema_builder = Schema::builder();
let field = schema_builder.add_ip_addr_field("ip_field", FAST);
let index = Index::create_in_ram(schema_builder.build());
{
let mut writer = index.writer_for_tests()?;
// IpV6 loopback
writer.add_document(doc!(field=>IpAddr::from_str("::1").unwrap().into_ipv6_addr()))?;
writer.add_document(doc!(field=>IpAddr::from_str("::1").unwrap().into_ipv6_addr()))?;
// IpV4
writer.add_document(
doc!(field=>IpAddr::from_str("127.0.0.1").unwrap().into_ipv6_addr()),
)?;
writer.commit()?;
}
let agg_req: Aggregations = serde_json::from_value(json!({
"cardinality": {
"cardinality": {
"field": "ip_field"
},
}
}))
.unwrap();
let res = exec_request(agg_req, &index)?;
assert_eq!(res["cardinality"]["value"], 2.0);
Ok(())
}
}
@@ -0,0 +1,397 @@
//! Segment collector for `cardinality` over a `ColumnType::Str` column.
//!
//! Strings are dictionary encoded, and resolving a term ordinal to its bytes
//! is the expensive part. So instead of hashing values during collection, the
//! collector accumulates *term ordinals* per bucket and, at finalization,
//! builds one shared term_ord -> coupon cache for every bucket at once. The
//! coupons are then appended into a [`CardinalityCollector`], which is the
//! same type the numeric collector produces — merging across segments and
//! across column kinds stays in the parent module.
use std::fmt::Debug;
use std::io;
use columnar::{Column, ColumnType, Dictionary};
use datasketches::hll::Coupon;
use rustc_hash::{FxBuildHasher, FxHashMap, FxHashSet};
use super::term_ord_accumulator::TermOrdAccumulator;
use super::CardinalityCollector;
use crate::aggregation::agg_data::AggregationsSegmentCtx;
use crate::aggregation::intermediate_agg_result::{
IntermediateAggregationResult, IntermediateAggregationResults, IntermediateMetricResult,
};
use crate::aggregation::segment_agg_result::SegmentAggregationCollector;
use crate::aggregation::*;
/// A CouponCache is here to cache the mapping term ordinal -> coupon (see above).
/// The idea is that we do not want to fetch terms associated to several term ordinals,
/// several times due to the fact that we have several buckets.
enum CouponCache {
Dense {
coupon_map: Vec<Coupon>,
missing_coupon_opt: Option<Coupon>,
},
Sparse {
coupon_map: FxHashMap<u64, Coupon>,
missing_coupon_opt: Option<Coupon>,
},
}
impl CouponCache {
fn new(
term_ords: Vec<u64>,
coupons: Vec<Coupon>,
missing_coupon_opt: Option<Coupon>,
) -> CouponCache {
let num_terms = term_ords.len();
assert_eq!(num_terms, coupons.len());
if term_ords.is_empty() {
return CouponCache::Dense {
coupon_map: Vec::new(),
missing_coupon_opt,
};
}
let highest_term_ord = term_ords.last().copied().unwrap_or(0u64);
// We prefer the dense implementation, if it is not too wasteful.
// There are two cases for which we can use it.
// 1- if the data is small.
// 2- if the data is not necessarily small, but due to a high occupancy ratio, the RAM usage
// is not that much bigger than if we had used a HashSet. (occupancy ratio + extra
// metadata ~ x2.25)
let should_use_dense =
highest_term_ord < 1_000_000u64 || highest_term_ord < num_terms as u64 * 3u64;
if should_use_dense {
// We don't really care about the value here. We will populate all the values we will
// read anyway.
let uninitialized_coupon = Coupon::from_hash(0);
let mut coupon_map: Vec<Coupon> =
vec![uninitialized_coupon; highest_term_ord as usize + 1];
for (term_ord, coupon) in term_ords.into_iter().zip(coupons) {
coupon_map[term_ord as usize] = coupon;
}
CouponCache::Dense {
coupon_map,
missing_coupon_opt,
}
} else {
let coupon_map: FxHashMap<u64, Coupon> = term_ords.into_iter().zip(coupons).collect();
CouponCache::Sparse {
coupon_map,
missing_coupon_opt,
}
}
}
}
/// Segment collector for `cardinality` over a `ColumnType::Str` column.
///
/// Hidden contract: the column passed at construction must be a str column
/// whose values are term ordinals of the associated dictionary, and
/// `max_term_ord_inclusive` must be `accessor.max_value()`. The missing
/// sentinel `accessor.max_value() + 1` may additionally be inserted when
/// `missing_value_for_accessor` is set, hence accumulators size for
/// `max_term_ord_inclusive + 1`.
pub(crate) struct SegmentStrCardinalityCollector<S: TermOrdAccumulator> {
/// Buckets are Some(_) until they get consumed by
/// `add_intermediate_aggregation_result`.
buckets: Vec<Option<S>>,
accessor_idx: usize,
/// The column accessor to access the fast field values (term ordinals).
accessor: Column<u64>,
/// The missing value normalized to the internal u64 representation of the field type.
missing_value_for_accessor: Option<u64>,
/// Lazily built at finalization time, shared by every bucket.
coupon_cache: Option<CouponCache>,
/// Largest term_ord that may be inserted into a bucket, i.e.
/// `accessor.max_value()`.
max_term_ord_inclusive: u64,
}
impl<S: TermOrdAccumulator> Debug for SegmentStrCardinalityCollector<S> {
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
f.debug_struct("SegmentStrCardinalityCollector")
.field("num_buckets", &self.buckets.len())
.field(
"missing_value_for_accessor",
&self.missing_value_for_accessor,
)
.finish()
}
}
/// Builds a coupon cache from the given buckets, dictionary, and optional missing value.
/// Returns a mapping from term_ord to the hash (coupon) of the associated term.
fn build_coupon_cache<S: TermOrdAccumulator>(
buckets: &[Option<S>],
dictionary: &Dictionary,
missing_value_opt: Option<&Key>,
) -> io::Result<CouponCache> {
// Pass 1 computes the capacity hint, pass 2 inserts.
let mut max_bucket_len = 0usize;
for bucket in buckets.iter().flatten() {
max_bucket_len = max_bucket_len.max(bucket.len());
}
let mut term_ords_set = FxHashSet::with_capacity_and_hasher(max_bucket_len * 2, FxBuildHasher);
for bucket in buckets.iter().flatten() {
term_ords_set.extend(bucket.iter_ords());
}
let mut term_ords: Vec<u64> = term_ords_set.into_iter().collect();
term_ords.sort_unstable();
term_ords.pop_if(|highest_term_ord| *highest_term_ord >= dictionary.num_terms() as u64);
let mut coupons: Vec<Coupon> = Vec::with_capacity(term_ords.len());
let all_term_ords_found: bool =
dictionary.sorted_ords_to_term_cb(&term_ords, |term_bytes| {
let coupon: Coupon = Coupon::from_hash(term_bytes);
coupons.push(coupon);
})?;
assert!(all_term_ords_found);
// Regardless of whether or not there is effectively a missing value in one of the buckets,
// we populate the cache with the missing key too (if any).
let missing_coupon_opt: Option<Coupon> = missing_value_opt.map(|missing_key| {
if let Key::Str(missing_value_str) = missing_key {
Coupon::from_hash(missing_value_str.as_bytes())
} else {
// See https://github.com/quickwit-oss/tantivy/issues/2891
// A missing key with a type different from Str will not work as intended
// for the moment.
//
// Right now this is just a partial workaround.
Coupon::from_hash("__tantivy_missing_non_str__".as_bytes())
}
});
Ok(CouponCache::new(term_ords, coupons, missing_coupon_opt))
}
fn append_to_sketch(
term_ords: &impl TermOrdAccumulator,
coupon_cache: &CouponCache,
sketch: &mut CardinalityCollector,
) {
match coupon_cache {
CouponCache::Dense {
coupon_map,
missing_coupon_opt,
} => {
if let Some(missing_coupon) = missing_coupon_opt {
for term_ord in term_ords.iter_ords() {
let coupon: Coupon = coupon_map
.get(term_ord as usize)
.copied()
.unwrap_or(*missing_coupon);
sketch.insert_coupon(coupon);
}
} else {
for term_ord in term_ords.iter_ords() {
if let Some(coupon) = coupon_map.get(term_ord as usize).copied() {
sketch.insert_coupon(coupon);
}
}
}
}
CouponCache::Sparse {
coupon_map,
missing_coupon_opt,
} => {
for term_ord in term_ords.iter_ords() {
if let Some(coupon) = coupon_map.get(&term_ord).copied().or(*missing_coupon_opt) {
sketch.insert_coupon(coupon);
}
}
}
}
}
impl<S: TermOrdAccumulator> SegmentStrCardinalityCollector<S> {
pub fn from_req(
accessor_idx: usize,
accessor: Column<u64>,
missing_value_for_accessor: Option<u64>,
max_term_ord_inclusive: u64,
) -> Self {
Self {
buckets: Vec::new(),
accessor_idx,
accessor,
missing_value_for_accessor,
coupon_cache: None,
max_term_ord_inclusive,
}
}
}
impl<S: TermOrdAccumulator + 'static> SegmentAggregationCollector
for SegmentStrCardinalityCollector<S>
{
fn add_intermediate_aggregation_result(
&mut self,
agg_data: &AggregationsSegmentCtx,
results: &mut IntermediateAggregationResults,
bucket_id: BucketId,
) -> crate::Result<()> {
self.prepare_max_bucket(bucket_id, agg_data)?;
let req_data = &agg_data.get_cardinality_req_data(self.accessor_idx);
let Some(str_dict_column) = &req_data.str_dict_column else {
return Err(crate::TantivyError::InternalError(
"a str cardinality collector requires a str dictionary column".to_string(),
));
};
// Strings are dictionary encoded. Fetching the terms associated to strings
// is expensive. For this reason, we do that once for all buckets and cache the results
// here.
//
// The cache maps a term_ord to the hash of the associated term. The missing value
// sentinel will be associated to the hash of the missing value if any.
if self.coupon_cache.is_none() {
self.coupon_cache = Some(build_coupon_cache(
&self.buckets,
str_dict_column.dictionary(),
req_data.req.missing.as_ref(),
)?);
}
let name = req_data.name.to_string();
// take the bucket in buckets and replace it with a new empty one
let Some(term_ords) = self.buckets[bucket_id as usize].take() else {
return Err(crate::TantivyError::InternalError(
"the same bucket should not be finalized twice.".to_string(),
));
};
let mut cardinality = CardinalityCollector::new(ColumnType::Str as u8);
if let Some(coupon_cache) = self.coupon_cache.as_ref() {
append_to_sketch(&term_ords, coupon_cache, &mut cardinality);
}
results.push(
name,
IntermediateAggregationResult::Metric(IntermediateMetricResult::Cardinality(
cardinality,
)),
)?;
Ok(())
}
fn collect(
&mut self,
parent_bucket_id: BucketId,
docs: &[crate::DocId],
agg_data: &mut AggregationsSegmentCtx,
) -> crate::Result<()> {
agg_data.column_block_accessor.fetch_block_with_missing(
docs,
&self.accessor,
self.missing_value_for_accessor,
);
let Some(term_ords) = self.buckets[parent_bucket_id as usize].as_mut() else {
return Err(crate::TantivyError::InternalError(
"collection should not happen after finalization".to_string(),
));
};
// Promotion check runs on the pre-block state: the first call
// sees an empty set (no-op), and the last block of inserts
// doesn't trigger a promotion of a set we won't grow further.
// The trait dispatches once per block (via `extend_from_iter`)
// for adaptive variants and inlines to a tight loop for the
// BitSet path.
term_ords.maybe_compact();
term_ords.extend_from_iter(agg_data.column_block_accessor.iter_vals());
Ok(())
}
fn prepare_max_bucket(
&mut self,
max_bucket: BucketId,
_agg_data: &AggregationsSegmentCtx,
) -> crate::Result<()> {
if max_bucket as usize >= self.buckets.len() {
let max_term_ord_inclusive = self.max_term_ord_inclusive;
self.buckets.resize_with(max_bucket as usize + 1, || {
Some(S::new(max_term_ord_inclusive))
});
}
Ok(())
}
fn compute_metric_value(
&self,
bucket_id: BucketId,
sub_agg_name: &str,
sub_agg_property: &str,
agg_data: &AggregationsSegmentCtx,
) -> Option<f64> {
let req_data = &agg_data.get_cardinality_req_data(self.accessor_idx);
if req_data.name != sub_agg_name || !sub_agg_property.is_empty() {
return None;
}
// The sketch isn't built until finalization; the term_ord set's len is
// the exact distinct count.
let term_ords = self.buckets.get(bucket_id as usize)?.as_ref()?;
Some(term_ords.len() as f64)
}
}
#[cfg(test)]
mod tests {
use crate::aggregation::agg_req::Aggregations;
use crate::aggregation::tests::{exec_request, get_test_index_from_terms};
use crate::schema::{Schema, FAST, STRING};
use crate::Index;
/// Build a single-segment string-cardinality index with 32 unique terms.
/// `column.max_value() = 31` is well below `BITSET_MAX_TERM_ORD`,
/// so the bucket exercises the `BitSet` path end to end.
#[test]
fn cardinality_aggregation_test_str_bitset() -> crate::Result<()> {
let terms: Vec<String> = (0..32).map(|i| format!("term_{i}")).collect();
let term_refs: Vec<Vec<&str>> = terms.iter().map(|t| vec![t.as_str()]).collect::<Vec<_>>();
// single segment so we have a single dictionary of 32 terms.
let index = get_test_index_from_terms(true, &term_refs)?;
let agg_req: Aggregations = serde_json::from_value(json!({
"cardinality": {
"cardinality": { "field": "string_id" }
},
}))
.unwrap();
let res = exec_request(agg_req, &index)?;
assert_eq!(res["cardinality"]["value"], 32.0);
Ok(())
}
/// `BitSet` path with a `missing` parameter: the column-level missing
/// sentinel (`column.max_value() + 1`) flows into the bitset, the
/// dict lookup filter at finalization drops it, and the missing
/// coupon is applied separately.
#[test]
fn cardinality_aggregation_test_str_bitset_with_missing() {
let mut schema_builder = Schema::builder();
let name_field = schema_builder.add_text_field("name", STRING | FAST);
let index = Index::create_in_ram(schema_builder.build());
let mut writer = index.writer_for_tests().unwrap();
for i in 0..16 {
let term = format!("t{i:02}");
writer.add_document(doc!(name_field => term)).unwrap();
}
// One empty doc, exercising the missing sentinel.
writer.add_document(doc!()).unwrap();
writer.commit().unwrap();
let agg_req: Aggregations = serde_json::from_value(json!({
"cardinality": {
"cardinality": {
"field": "name",
"missing": "MISSING_SENTINEL_KEY",
}
},
}))
.unwrap();
let res = exec_request(agg_req, &index).unwrap();
// 16 distinct real terms + 1 distinct "missing" value = 17.
assert_eq!(res["cardinality"]["value"], 17.0);
}
}
@@ -0,0 +1,343 @@
//! Per-bucket term-ordinal accumulators used by the str cardinality
//! collector.
//!
//! A str cardinality bucket needs a *set of term ordinals*, and the right
//! representation depends on how large the segment's dictionary slice is:
//!
//! * [`BitSet`] (from `common`): used when `column.max_value()` is small (<
//! [`BITSET_MAX_TERM_ORD`]). Pre-allocated, no promotion machinery.
//! * [`TermOrdSet`]: adaptive. Starts as an `FxHashSet` (cheap when few ords are seen) and
//! promotes to a [`PagedBitset`] once occupancy crosses the density threshold.
//!
//! Both are exposed through the [`TermOrdAccumulator`] trait so that
//! `SegmentStrCardinalityCollector` can be generic over the choice and the hot
//! `collect()` loop monomorphizes to a direct call (no enum dispatch per
//! insert).
use common::{BitSet, TinySet};
use rustc_hash::FxHashSet;
/// Promote FxHashSet<u64> -> PagedBitset at ~3% density (`len * 32 >
/// dict_num_terms`). Past this point the bitset (~`dict_num_terms / 7.5`
/// bytes) is smaller than the hashset (~10 B/entry minimum) and avoids
/// the per-insert hash.
const PROMOTION_RATIO: u64 = 32;
// =================================================================
// PagedBitset: a sparse bitset indexed by term_ord.
//
// Used as the dense alternative to FxHashSet<u64> once a string
// cardinality bucket has accumulated enough unique term ordinals.
// Memory is bounded to (touched pages) * (page bytes), not
// (max_term_ord / 8).
//
// Page geometry mirrors `PagedTermMap` in `term_agg.rs`: 1024 ords
// per page, lazy `Vec<Option<Box<Page>>>` directory.
// =================================================================
const BITSET_PAGE_SHIFT: u32 = 10;
const BITSET_PAGE_BITS: u64 = 1u64 << BITSET_PAGE_SHIFT; // 1024
const BITSET_PAGE_MASK: u64 = BITSET_PAGE_BITS - 1;
const BITSET_WORDS_PER_PAGE: usize = (BITSET_PAGE_BITS / 64) as usize; // 16
#[derive(Clone)]
struct PagedBitsetPage {
words: [TinySet; BITSET_WORDS_PER_PAGE],
}
impl PagedBitsetPage {
fn new() -> Self {
Self {
words: [TinySet::empty(); BITSET_WORDS_PER_PAGE],
}
}
}
pub(crate) struct PagedBitset {
pages: Vec<Option<Box<PagedBitsetPage>>>,
/// Cached number of set bits, maintained on insert.
count: u64,
}
impl PagedBitset {
/// Allocates a directory big enough to hold ords up to and including
/// `max_term_ord`. Pages are allocated lazily on first set.
fn with_max_term_ord(max_term_ord: u64) -> Self {
let max_page_idx = (max_term_ord >> BITSET_PAGE_SHIFT) as usize;
let num_pages = max_page_idx + 1;
Self {
pages: vec![None; num_pages],
count: 0,
}
}
#[inline]
fn insert(&mut self, term_ord: u64) {
let page_idx = (term_ord >> BITSET_PAGE_SHIFT) as usize;
let intra = term_ord & BITSET_PAGE_MASK;
let word_idx = (intra >> 6) as usize;
let bit_idx = (intra & 63) as u32;
let page = match &mut self.pages[page_idx] {
Some(p) => p,
None => {
self.pages[page_idx] = Some(Box::new(PagedBitsetPage::new()));
self.pages[page_idx].as_mut().unwrap()
}
};
if page.words[word_idx].insert_mut(bit_idx) {
self.count += 1;
}
}
/// Number of set bits. O(1).
#[inline]
fn len(&self) -> u64 {
self.count
}
/// Iterate set ords in ascending order.
fn iter_sorted(&self) -> impl Iterator<Item = u64> + '_ {
self.pages
.iter()
.enumerate()
.filter_map(|(page_idx, page_opt)| page_opt.as_ref().map(|p| (page_idx, p)))
.flat_map(|(page_idx, page)| {
let page_base_ord = (page_idx as u64) << BITSET_PAGE_SHIFT;
page.words
.iter()
.enumerate()
.flat_map(move |(word_idx, &word)| {
let word_base_ord = page_base_ord + (word_idx as u64) * 64;
word.into_iter()
.map(move |bit| word_base_ord + u64::from(bit))
})
})
}
}
/// Threshold below which we use `BitSet` instead of `TermOrdSet`.
///
/// Both `BitSet` and `FxHashSet<u64>` have the same 32-byte struct, so the comparison is heap only:
/// * `BitSet` at T=256: 5 `TinySet` words covering 258 bits (with the missing-value sentinel) =
/// 40 bytes.
/// * `FxHashSet<u64>` after one insert: 4-bucket hashbrown table ≈ 56 bytes
pub(crate) const BITSET_MAX_TERM_ORD: u64 = 256;
// =================================================================
// TermOrdAccumulator: per-bucket abstraction over the entries set.
//
// Implementations:
// - `BitSet` (from `common`): used when `column.max_value()` is small (< BITSET_MAX_TERM_ORD).
// Pre-allocated, no promotion.
// - `TermOrdSet`: adaptive, starts as FxHashSet and promotes to a paged bitset when occupancy
// crosses the density threshold (only if promotion is enabled — typically gated on top-level
// aggregation).
//
// The trait lets `SegmentStrCardinalityCollector` be generic over the choice
// so the hot collect() loop monomorphizes to a direct call (no enum
// dispatch per insert).
// =================================================================
pub(crate) trait TermOrdAccumulator: Sized {
/// Construct an empty accumulator.
/// `max_term_ord_inclusive` is the largest term_ord that may be
/// inserted (used to size pre-allocated bitsets and the dense bitset
/// on promotion).
fn new(max_term_ord_inclusive: u64) -> Self;
fn insert(&mut self, term_ord: u64);
fn extend_from_iter(&mut self, ords: impl IntoIterator<Item = u64>);
/// Hook called once per ingested block. Adaptive impls use this to
/// decide on sparse->dense promotion.
fn maybe_compact(&mut self) {}
fn len(&self) -> usize;
fn iter_ords(&self) -> impl Iterator<Item = u64> + '_;
}
impl TermOrdAccumulator for BitSet {
#[inline]
fn new(max_term_ord_inclusive: u64) -> Self {
// `BitSet::with_max_value(M)` accepts ords in [0, M).
// We need ords up to and including `max_term_ord_inclusive`, plus
// the missing-value sentinel `column.max_value() + 1`.
BitSet::with_max_value((max_term_ord_inclusive + 2) as u32)
}
#[inline]
fn insert(&mut self, term_ord: u64) {
BitSet::insert(self, term_ord as u32);
}
#[inline]
fn len(&self) -> usize {
BitSet::len(self)
}
fn iter_ords(&self) -> impl Iterator<Item = u64> + '_ {
// `BitSet` itself doesn't expose iteration, but
// `BitSet::tinyset(bucket)` does. Walk per-bucket and yield each
// set bit. The capacity is `max_value()`; iterating to
// `div_ceil(64)` covers every possible ord exactly once.
let num_buckets = self.max_value().div_ceil(64);
(0..num_buckets).flat_map(move |bucket| {
let chunk_base = u64::from(bucket) * 64;
self.tinyset(bucket)
.into_iter()
.map(move |bit| chunk_base + u64::from(bit))
})
}
#[inline(never)] //< required to not have a perf regression
fn extend_from_iter(&mut self, ords: impl IntoIterator<Item = u64>) {
for ord in ords {
<Self as TermOrdAccumulator>::insert(self, ord);
}
}
}
// TermOrdSet: adaptive sparse->dense accumulator.
//
// Starts as an HashSet (cheap when few ords are seen). When occupancy
// crosses `len * PROMOTION_RATIO > max_term_ord_inclusive`, drains into
// a `PagedBitset` and continues dense.
pub(crate) struct TermOrdSet {
inner: TermOrdSetInner,
/// Largest term_ord that may be inserted. Used for both sizing the
/// dense bitset on promotion and as the promotion-threshold reference.
max_term_ord_inclusive: u64,
}
enum TermOrdSetInner {
Sparse(FxHashSet<u64>),
Dense(PagedBitset),
}
impl TermOrdAccumulator for TermOrdSet {
fn new(max_term_ord_inclusive: u64) -> Self {
Self {
inner: TermOrdSetInner::Sparse(FxHashSet::default()),
max_term_ord_inclusive,
}
}
#[inline]
fn insert(&mut self, term_ord: u64) {
match &mut self.inner {
TermOrdSetInner::Sparse(set) => {
set.insert(term_ord);
}
TermOrdSetInner::Dense(bitset) => bitset.insert(term_ord),
}
}
fn extend_from_iter(&mut self, ords: impl IntoIterator<Item = u64>) {
match &mut self.inner {
TermOrdSetInner::Sparse(set) => {
set.extend(ords);
}
TermOrdSetInner::Dense(bitset) => {
for ord in ords {
bitset.insert(ord);
}
}
}
}
fn maybe_compact(&mut self) {
let TermOrdSetInner::Sparse(set) = &mut self.inner else {
return;
};
if set.len() as u64 * PROMOTION_RATIO <= self.max_term_ord_inclusive {
return;
}
let mut bitset = PagedBitset::with_max_term_ord(self.max_term_ord_inclusive + 1);
let set = std::mem::take(set);
for ord in set {
bitset.insert(ord);
}
self.inner = TermOrdSetInner::Dense(bitset);
}
fn len(&self) -> usize {
match &self.inner {
TermOrdSetInner::Sparse(set) => set.len(),
TermOrdSetInner::Dense(bitset) => bitset.len() as usize,
}
}
fn iter_ords(&self) -> impl Iterator<Item = u64> + '_ {
match &self.inner {
TermOrdSetInner::Sparse(set) => itertools::Either::Left(set.iter().copied()),
TermOrdSetInner::Dense(bitset) => itertools::Either::Right(bitset.iter_sorted()),
}
}
}
#[cfg(test)]
mod tests {
use common::BitSet;
use super::{PagedBitset, TermOrdAccumulator, TermOrdSet, PROMOTION_RATIO};
/// Unit-test the PagedBitset itself: cross-page inserts produce sorted
/// iteration, len() matches the inserted set, and duplicates are
/// idempotent.
#[test]
fn paged_bitset_basic() {
// Span several pages: BITSET_PAGE_BITS = 1024, so ords > 1024 land
// on the second page, > 2048 on the third, etc.
let ords = [0u64, 1, 63, 64, 1023, 1024, 1025, 4096, 4097, 9999, 10_000];
let max_ord = *ords.iter().max().unwrap();
let mut bitset = PagedBitset::with_max_term_ord(max_ord);
for &ord in &ords {
bitset.insert(ord);
// Idempotent: inserting again must not increase count.
bitset.insert(ord);
}
assert_eq!(bitset.len(), ords.len() as u64);
let collected: Vec<u64> = bitset.iter_sorted().collect();
let mut expected: Vec<u64> = ords.to_vec();
expected.sort_unstable();
assert_eq!(collected, expected);
}
/// Unit-test `TermOrdSet`: starts Sparse, promotes to Dense on
/// `maybe_compact` once the density threshold is crossed, and
/// `iter_ords()` yields the same set in either state. Ords spanning
/// multiple paged-bitset pages exercise the Dense iter ordering.
#[test]
fn term_ord_set_promotes_on_maybe_compact() {
// Pick max so promotion needs few inserts: len * RATIO > max with
// RATIO=32 and max=64 trips at len=3 (3*32=96 > 64).
let max_term_ord = 64u64;
let mut set = <TermOrdSet as TermOrdAccumulator>::new(max_term_ord);
// Two inserts: should stay Sparse after maybe_compact (2 * RATIO = 64, not > 64).
set.insert(0);
set.insert(7);
set.maybe_compact();
assert_eq!(set.len(), 2);
// Third insert promotes on next maybe_compact.
set.insert(20);
assert_eq!(set.len(), 3);
// Sanity check: at len=3, 3 * PROMOTION_RATIO = 96 > 64.
assert!(3u64 * PROMOTION_RATIO > max_term_ord);
set.maybe_compact();
// Post-promotion: extending continues to work.
set.insert(15);
set.insert(15); // dup
assert_eq!(set.len(), 4);
let mut collected: Vec<u64> = set.iter_ords().collect();
collected.sort_unstable();
assert_eq!(collected, vec![0, 7, 15, 20]);
}
/// Unit-test the `BitSet` impl of `TermOrdAccumulator`: insert,
/// dedup, and iter_ords order.
#[test]
fn bitset_accumulator_basic() {
let mut set = <BitSet as TermOrdAccumulator>::new(255);
for ord in [0u64, 1, 63, 64, 65, 128, 200, 200, 0] {
<BitSet as TermOrdAccumulator>::insert(&mut set, ord);
}
assert_eq!(<BitSet as TermOrdAccumulator>::len(&set), 7);
let collected: Vec<u64> = set.iter_ords().collect();
assert_eq!(collected, vec![0, 1, 63, 64, 65, 128, 200]);
}
}