261 lines
9.5 KiB
Rust
261 lines
9.5 KiB
Rust
use std::collections::{HashSet, BTreeMap};
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use std::ops::Bound::Unbounded;
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use std::{cmp, fmt};
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use anyhow::Context;
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use heed::BytesDecode;
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use roaring::RoaringBitmap;
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use crate::facet::{FacetType, FacetValue};
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use crate::heed_codec::facet::{FacetValueStringCodec, FacetLevelValueF64Codec, FacetLevelValueI64Codec};
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use crate::heed_codec::facet::{FieldDocIdFacetStringCodec, FieldDocIdFacetF64Codec, FieldDocIdFacetI64Codec};
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use crate::search::facet::{FacetIter, FacetRange};
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use crate::{Index, FieldId, DocumentId};
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/// The default number of values by facets that will
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/// be fetched from the key-value store.
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const DEFAULT_VALUES_BY_FACET: usize = 100;
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/// The hard limit in the number of values by facets that will be fetched from
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/// the key-value store. Searching for more values could slow down the engine.
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const MAX_VALUES_BY_FACET: usize = 1000;
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/// Threshold on the number of candidates that will make
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/// the system to choose between one algorithm or another.
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const CANDIDATES_THRESHOLD: u64 = 1000;
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pub struct FacetDistribution<'a> {
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facets: Option<HashSet<String>>,
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candidates: Option<RoaringBitmap>,
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max_values_by_facet: usize,
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rtxn: &'a heed::RoTxn<'a>,
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index: &'a Index,
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}
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impl<'a> FacetDistribution<'a> {
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pub fn new(rtxn: &'a heed::RoTxn, index: &'a Index) -> FacetDistribution<'a> {
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FacetDistribution {
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facets: None,
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candidates: None,
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max_values_by_facet: DEFAULT_VALUES_BY_FACET,
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rtxn,
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index,
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}
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}
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pub fn facets<I: IntoIterator<Item=A>, A: AsRef<str>>(&mut self, names: I) -> &mut Self {
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self.facets = Some(names.into_iter().map(|s| s.as_ref().to_string()).collect());
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self
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}
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pub fn candidates(&mut self, candidates: RoaringBitmap) -> &mut Self {
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self.candidates = Some(candidates);
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self
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}
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pub fn max_values_by_facet(&mut self, max: usize) -> &mut Self {
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self.max_values_by_facet = cmp::min(max, MAX_VALUES_BY_FACET);
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self
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}
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/// There is a small amount of candidates OR we ask for facet string values so we
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/// decide to iterate over the facet values of each one of them, one by one.
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fn facet_values_from_documents(
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&self,
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field_id: FieldId,
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facet_type: FacetType,
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candidates: &RoaringBitmap,
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) -> heed::Result<BTreeMap<FacetValue, u64>>
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{
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fn fetch_facet_values<'t, KC, K: 't>(
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index: &Index,
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rtxn: &'t heed::RoTxn,
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field_id: FieldId,
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candidates: &RoaringBitmap,
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) -> heed::Result<BTreeMap<FacetValue, u64>>
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where
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KC: BytesDecode<'t, DItem = (FieldId, DocumentId, K)>,
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K: Into<FacetValue>,
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{
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let mut facet_values = BTreeMap::new();
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let mut key_buffer = vec![field_id];
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for docid in candidates.into_iter().take(CANDIDATES_THRESHOLD as usize) {
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key_buffer.truncate(1);
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key_buffer.extend_from_slice(&docid.to_be_bytes());
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let iter = index.field_id_docid_facet_values
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.prefix_iter(rtxn, &key_buffer)?
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.remap_key_type::<KC>();
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for result in iter {
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let ((_, _, value), ()) = result?;
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*facet_values.entry(value.into()).or_insert(0) += 1;
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}
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}
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Ok(facet_values)
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}
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let index = self.index;
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let rtxn = self.rtxn;
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match facet_type {
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FacetType::String => {
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fetch_facet_values::<FieldDocIdFacetStringCodec, _>(index, rtxn, field_id, candidates)
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},
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FacetType::Float => {
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fetch_facet_values::<FieldDocIdFacetF64Codec, _>(index, rtxn, field_id, candidates)
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},
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FacetType::Integer => {
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fetch_facet_values::<FieldDocIdFacetI64Codec, _>(index, rtxn, field_id, candidates)
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},
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}
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}
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/// There is too much documents, we use the facet levels to move throught
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/// the facet values, to find the candidates and values associated.
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fn facet_values_from_facet_levels(
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&self,
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field_id: FieldId,
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facet_type: FacetType,
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candidates: &RoaringBitmap,
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) -> heed::Result<BTreeMap<FacetValue, u64>>
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{
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let iter = match facet_type {
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FacetType::String => unreachable!(),
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FacetType::Float => {
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let iter = FacetIter::<f64, FacetLevelValueF64Codec>::new_non_reducing(
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self.rtxn, self.index, field_id, candidates.clone(),
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)?;
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let iter = iter.map(|r| r.map(|(v, docids)| (FacetValue::from(v), docids)));
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Box::new(iter) as Box::<dyn Iterator<Item=_>>
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},
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FacetType::Integer => {
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let iter = FacetIter::<i64, FacetLevelValueI64Codec>::new_non_reducing(
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self.rtxn, self.index, field_id, candidates.clone(),
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)?;
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Box::new(iter.map(|r| r.map(|(v, docids)| (FacetValue::from(v), docids))))
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},
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};
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let mut facet_values = BTreeMap::new();
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for result in iter {
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let (value, mut docids) = result?;
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docids.intersect_with(candidates);
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if !docids.is_empty() {
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facet_values.insert(value, docids.len());
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}
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if facet_values.len() == self.max_values_by_facet {
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break;
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}
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}
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Ok(facet_values)
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}
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/// Placeholder search, a.k.a. no candidates were specified. We iterate throught the
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/// facet values one by one and iterate on the facet level 0 for numbers.
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fn facet_values_from_raw_facet_database(
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&self,
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field_id: FieldId,
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facet_type: FacetType,
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) -> heed::Result<BTreeMap<FacetValue, u64>>
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{
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let db = self.index.facet_field_id_value_docids;
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let level = 0;
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let iter = match facet_type {
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FacetType::String => {
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let iter = db
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.prefix_iter(self.rtxn, &[field_id])?
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.remap_key_type::<FacetValueStringCodec>()
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.map(|r| r.map(|((_, v), docids)| (FacetValue::from(v), docids)));
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Box::new(iter) as Box::<dyn Iterator<Item=_>>
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},
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FacetType::Float => {
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let db = db.remap_key_type::<FacetLevelValueF64Codec>();
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let range = FacetRange::<f64, _>::new(
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self.rtxn, db, field_id, level, Unbounded, Unbounded,
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)?;
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Box::new(range.map(|r| r.map(|((_, _, v, _), docids)| (FacetValue::from(v), docids))))
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},
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FacetType::Integer => {
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let db = db.remap_key_type::<FacetLevelValueI64Codec>();
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let range = FacetRange::<i64, _>::new(
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self.rtxn, db, field_id, level, Unbounded, Unbounded,
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)?;
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Box::new(range.map(|r| r.map(|((_, _, v, _), docids)| (FacetValue::from(v), docids))))
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},
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};
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let mut facet_values = BTreeMap::new();
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for result in iter {
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let (value, docids) = result?;
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facet_values.insert(value, docids.len());
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if facet_values.len() == self.max_values_by_facet {
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break;
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}
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}
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Ok(facet_values)
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}
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fn facet_values(
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&self,
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field_id: FieldId,
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facet_type: FacetType,
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) -> heed::Result<BTreeMap<FacetValue, u64>>
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{
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if let Some(candidates) = self.candidates.as_ref() {
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// Classic search, candidates were specified, we must return facet values only related
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// to those candidates. We also enter here for facet strings for performance reasons.
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if candidates.len() <= CANDIDATES_THRESHOLD || facet_type == FacetType::String {
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self.facet_values_from_documents(field_id, facet_type, candidates)
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} else {
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self.facet_values_from_facet_levels(field_id, facet_type, candidates)
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}
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} else {
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self.facet_values_from_raw_facet_database(field_id, facet_type)
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}
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}
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pub fn execute(&self) -> anyhow::Result<BTreeMap<String, BTreeMap<FacetValue, u64>>> {
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let fields_ids_map = self.index.fields_ids_map(self.rtxn)?;
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let faceted_fields = self.index.faceted_fields(self.rtxn)?;
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let fields_ids: Vec<_> = match &self.facets {
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Some(names) => names
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.iter()
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.filter_map(|n| faceted_fields.get(n).map(|t| (n.to_string(), *t)))
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.collect(),
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None => faceted_fields.into_iter().collect(),
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};
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let mut facets_values = BTreeMap::new();
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for (name, ftype) in fields_ids {
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let fid = fields_ids_map.id(&name).with_context(|| {
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format!("missing field name {:?} from the fields id map", name)
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})?;
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let values = self.facet_values(fid, ftype)?;
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facets_values.insert(name, values);
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}
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Ok(facets_values)
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}
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}
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impl fmt::Debug for FacetDistribution<'_> {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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let FacetDistribution {
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facets,
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candidates,
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max_values_by_facet,
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rtxn: _,
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index: _,
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} = self;
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f.debug_struct("FacetDistribution")
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.field("facets", facets)
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.field("candidates", candidates)
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.field("max_values_by_facet", max_values_by_facet)
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.finish()
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}
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}
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