MeiliSearch/milli/src/search/facet/search.rs

327 lines
12 KiB
Rust

use std::cmp::{Ordering, Reverse};
use std::collections::BinaryHeap;
use std::ops::ControlFlow;
use charabia::normalizer::NormalizerOption;
use charabia::Normalize;
use fst::automaton::{Automaton, Str};
use fst::{IntoStreamer, Streamer};
use roaring::RoaringBitmap;
use tracing::error;
use crate::error::UserError;
use crate::heed_codec::facet::{FacetGroupKey, FacetGroupValue};
use crate::search::build_dfa;
use crate::{DocumentId, FieldId, OrderBy, Result, Search};
/// The maximum number of values per facet returned by the facet search route.
const DEFAULT_MAX_NUMBER_OF_VALUES_PER_FACET: usize = 100;
pub struct SearchForFacetValues<'a> {
query: Option<String>,
facet: String,
search_query: Search<'a>,
max_values: usize,
is_hybrid: bool,
}
impl<'a> SearchForFacetValues<'a> {
pub fn new(
facet: String,
search_query: Search<'a>,
is_hybrid: bool,
) -> SearchForFacetValues<'a> {
SearchForFacetValues {
query: None,
facet,
search_query,
max_values: DEFAULT_MAX_NUMBER_OF_VALUES_PER_FACET,
is_hybrid,
}
}
pub fn query(&mut self, query: impl Into<String>) -> &mut Self {
self.query = Some(query.into());
self
}
pub fn max_values(&mut self, max: usize) -> &mut Self {
self.max_values = max;
self
}
fn one_original_value_of(
&self,
field_id: FieldId,
facet_str: &str,
any_docid: DocumentId,
) -> Result<Option<String>> {
let index = self.search_query.index;
let rtxn = self.search_query.rtxn;
let key: (FieldId, _, &str) = (field_id, any_docid, facet_str);
Ok(index.field_id_docid_facet_strings.get(rtxn, &key)?.map(|v| v.to_owned()))
}
pub fn execute(&self) -> Result<Vec<FacetValueHit>> {
let index = self.search_query.index;
let rtxn = self.search_query.rtxn;
let filterable_fields = index.filterable_fields(rtxn)?;
if !filterable_fields.contains(&self.facet) {
let (valid_fields, hidden_fields) =
index.remove_hidden_fields(rtxn, filterable_fields)?;
return Err(UserError::InvalidFacetSearchFacetName {
field: self.facet.clone(),
valid_fields,
hidden_fields,
}
.into());
}
let fields_ids_map = index.fields_ids_map(rtxn)?;
let fid = match fields_ids_map.id(&self.facet) {
Some(fid) => fid,
// we return an empty list of results when the attribute has been
// set as filterable but no document contains this field (yet).
None => return Ok(Vec::new()),
};
let fst = match self.search_query.index.facet_id_string_fst.get(rtxn, &fid)? {
Some(fst) => fst,
None => return Ok(Vec::new()),
};
let search_candidates = self
.search_query
.execute_for_candidates(self.is_hybrid || self.search_query.vector.is_some())?;
let mut results = match index.sort_facet_values_by(rtxn)?.get(&self.facet) {
OrderBy::Lexicographic => ValuesCollection::by_lexicographic(self.max_values),
OrderBy::Count => ValuesCollection::by_count(self.max_values),
};
match self.query.as_ref() {
Some(query) => {
let options = NormalizerOption { lossy: true, ..Default::default() };
let query = query.normalize(&options);
let query = query.as_ref();
let authorize_typos = self.search_query.index.authorize_typos(rtxn)?;
let field_authorizes_typos =
!self.search_query.index.exact_attributes_ids(rtxn)?.contains(&fid);
if authorize_typos && field_authorizes_typos {
let exact_words_fst = self.search_query.index.exact_words(rtxn)?;
if exact_words_fst.map_or(false, |fst| fst.contains(query)) {
if fst.contains(query) {
self.fetch_original_facets_using_normalized(
fid,
query,
query,
&search_candidates,
&mut results,
)?;
}
} else {
let one_typo = self.search_query.index.min_word_len_one_typo(rtxn)?;
let two_typos = self.search_query.index.min_word_len_two_typos(rtxn)?;
let is_prefix = true;
let automaton = if query.len() < one_typo as usize {
build_dfa(query, 0, is_prefix)
} else if query.len() < two_typos as usize {
build_dfa(query, 1, is_prefix)
} else {
build_dfa(query, 2, is_prefix)
};
let mut stream = fst.search(automaton).into_stream();
while let Some(facet_value) = stream.next() {
let value = std::str::from_utf8(facet_value)?;
if self
.fetch_original_facets_using_normalized(
fid,
value,
query,
&search_candidates,
&mut results,
)?
.is_break()
{
break;
}
}
}
} else {
let automaton = Str::new(query).starts_with();
let mut stream = fst.search(automaton).into_stream();
while let Some(facet_value) = stream.next() {
let value = std::str::from_utf8(facet_value)?;
if self
.fetch_original_facets_using_normalized(
fid,
value,
query,
&search_candidates,
&mut results,
)?
.is_break()
{
break;
}
}
}
}
None => {
let prefix = FacetGroupKey { field_id: fid, level: 0, left_bound: "" };
for result in index.facet_id_string_docids.prefix_iter(rtxn, &prefix)? {
let (FacetGroupKey { left_bound, .. }, FacetGroupValue { bitmap, .. }) =
result?;
let count = search_candidates.intersection_len(&bitmap);
if count != 0 {
let value = self
.one_original_value_of(fid, left_bound, bitmap.min().unwrap())?
.unwrap_or_else(|| left_bound.to_string());
if results.insert(FacetValueHit { value, count }).is_break() {
break;
}
}
}
}
}
Ok(results.into_sorted_vec())
}
fn fetch_original_facets_using_normalized(
&self,
fid: FieldId,
value: &str,
query: &str,
search_candidates: &RoaringBitmap,
results: &mut ValuesCollection,
) -> Result<ControlFlow<()>> {
let index = self.search_query.index;
let rtxn = self.search_query.rtxn;
let database = index.facet_id_normalized_string_strings;
let key = (fid, value);
let original_strings = match database.get(rtxn, &key)? {
Some(original_strings) => original_strings,
None => {
error!("the facet value is missing from the facet database: {key:?}");
return Ok(ControlFlow::Continue(()));
}
};
for original in original_strings {
let key = FacetGroupKey { field_id: fid, level: 0, left_bound: original.as_str() };
let docids = match index.facet_id_string_docids.get(rtxn, &key)? {
Some(FacetGroupValue { bitmap, .. }) => bitmap,
None => {
error!("the facet value is missing from the facet database: {key:?}");
return Ok(ControlFlow::Continue(()));
}
};
let count = search_candidates.intersection_len(&docids);
if count != 0 {
let value = self
.one_original_value_of(fid, &original, docids.min().unwrap())?
.unwrap_or_else(|| query.to_string());
if results.insert(FacetValueHit { value, count }).is_break() {
break;
}
}
}
Ok(ControlFlow::Continue(()))
}
}
#[derive(Debug, Clone, serde::Serialize, PartialEq)]
pub struct FacetValueHit {
/// The original facet value
pub value: String,
/// The number of documents associated to this facet
pub count: u64,
}
impl PartialOrd for FacetValueHit {
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
Some(self.cmp(other))
}
}
impl Ord for FacetValueHit {
fn cmp(&self, other: &Self) -> Ordering {
self.count.cmp(&other.count).then_with(|| self.value.cmp(&other.value))
}
}
impl Eq for FacetValueHit {}
/// A wrapper type that collects the best facet values by
/// lexicographic or number of associated values.
enum ValuesCollection {
/// Keeps the top values according to the lexicographic order.
Lexicographic { max: usize, content: Vec<FacetValueHit> },
/// Keeps the top values according to the number of values associated to them.
///
/// Note that it is a max heap and we need to move the smallest counts
/// at the top to be able to pop them when we reach the max_values limit.
Count { max: usize, content: BinaryHeap<Reverse<FacetValueHit>> },
}
impl ValuesCollection {
pub fn by_lexicographic(max: usize) -> Self {
ValuesCollection::Lexicographic { max, content: Vec::new() }
}
pub fn by_count(max: usize) -> Self {
ValuesCollection::Count { max, content: BinaryHeap::new() }
}
pub fn insert(&mut self, value: FacetValueHit) -> ControlFlow<()> {
match self {
ValuesCollection::Lexicographic { max, content } => {
if content.len() < *max {
content.push(value);
if content.len() < *max {
return ControlFlow::Continue(());
}
}
ControlFlow::Break(())
}
ValuesCollection::Count { max, content } => {
if content.len() == *max {
// Peeking gives us the worst value in the list as
// this is a max-heap and we reversed it.
let Some(mut peek) = content.peek_mut() else { return ControlFlow::Break(()) };
if peek.0.count <= value.count {
// Replace the current worst value in the heap
// with the new one we received that is better.
*peek = Reverse(value);
}
} else {
content.push(Reverse(value));
}
ControlFlow::Continue(())
}
}
}
/// Returns the list of facet values in descending order of, either,
/// count or lexicographic order of the value depending on the type.
pub fn into_sorted_vec(self) -> Vec<FacetValueHit> {
match self {
ValuesCollection::Lexicographic { content, .. } => content.into_iter().collect(),
ValuesCollection::Count { content, .. } => {
// Convert the heap into a vec of hits by removing the Reverse wrapper.
// Hits are already in the right order as they were reversed and there
// are output in ascending order.
content.into_sorted_vec().into_iter().map(|Reverse(hit)| hit).collect()
}
}
}
}