Expose a sortFacetValuesBy parameter to the user

meilisearch/src/routes/indexes/search.rs

@@ -16,9 +16,9 @@ use crate::extractors::authentication::policies::*;
 use crate::extractors::authentication::GuardedData;
 use crate::extractors::sequential_extractor::SeqHandler;
 use crate::search::{
-    add_search_rules, perform_search, MatchingStrategy, SearchQuery, DEFAULT_CROP_LENGTH,
+    add_search_rules, perform_search, FacetValuesSort, MatchingStrategy, SearchQuery,
-    DEFAULT_CROP_MARKER, DEFAULT_HIGHLIGHT_POST_TAG, DEFAULT_HIGHLIGHT_PRE_TAG,
+    DEFAULT_CROP_LENGTH, DEFAULT_CROP_MARKER, DEFAULT_HIGHLIGHT_POST_TAG,
-    DEFAULT_SEARCH_LIMIT, DEFAULT_SEARCH_OFFSET,
+    DEFAULT_HIGHLIGHT_PRE_TAG, DEFAULT_SEARCH_LIMIT, DEFAULT_SEARCH_OFFSET,
 };
 
 pub fn configure(cfg: &mut web::ServiceConfig) {
@@ -64,6 +64,8 @@ pub struct SearchQueryGet {
     show_ranking_score_details: Param<bool>,
     #[deserr(default, error = DeserrQueryParamError<InvalidSearchFacets>)]
     facets: Option<CS<String>>,
+    #[deserr(default, error = DeserrQueryParamError<InvalidSearchFacets>)]
+    sort_facet_values_by: Option<FacetValuesSort>,
     #[deserr( default = DEFAULT_HIGHLIGHT_PRE_TAG(), error = DeserrQueryParamError<InvalidSearchHighlightPreTag>)]
     highlight_pre_tag: String,
     #[deserr( default = DEFAULT_HIGHLIGHT_POST_TAG(), error = DeserrQueryParamError<InvalidSearchHighlightPostTag>)]
@@ -103,6 +105,7 @@ impl From<SearchQueryGet> for SearchQuery {
             show_ranking_score: other.show_ranking_score.0,
             show_ranking_score_details: other.show_ranking_score_details.0,
             facets: other.facets.map(|o| o.into_iter().collect()),
+            sort_facet_values_by: other.sort_facet_values_by,
             highlight_pre_tag: other.highlight_pre_tag,
             highlight_post_tag: other.highlight_post_tag,
             crop_marker: other.crop_marker,

meilisearch/src/search.rs

@@ -14,7 +14,7 @@ use meilisearch_types::heed::RoTxn;
 use meilisearch_types::index_uid::IndexUid;
 use meilisearch_types::milli::score_details::{ScoreDetails, ScoringStrategy};
 use meilisearch_types::milli::{
-    dot_product_similarity, FacetValueHit, InternalError, SearchForFacetValues,
+    dot_product_similarity, FacetValueHit, OrderBy, InternalError, SearchForFacetValues,
 };
 use meilisearch_types::settings::DEFAULT_PAGINATION_MAX_TOTAL_HITS;
 use meilisearch_types::{milli, Document};
@@ -74,6 +74,8 @@ pub struct SearchQuery {
     pub sort: Option<Vec<String>>,
     #[deserr(default, error = DeserrJsonError<InvalidSearchFacets>)]
     pub facets: Option<Vec<String>>,
+    #[deserr(default, error = DeserrJsonError<InvalidSearchFacets>)] // TODO
+    pub sort_facet_values_by: Option<FacetValuesSort>,
     #[deserr(default, error = DeserrJsonError<InvalidSearchHighlightPreTag>, default = DEFAULT_HIGHLIGHT_PRE_TAG())]
     pub highlight_pre_tag: String,
     #[deserr(default, error = DeserrJsonError<InvalidSearchHighlightPostTag>, default = DEFAULT_HIGHLIGHT_POST_TAG())]
@@ -133,6 +135,8 @@ pub struct SearchQueryWithIndex {
     pub sort: Option<Vec<String>>,
     #[deserr(default, error = DeserrJsonError<InvalidSearchFacets>)]
     pub facets: Option<Vec<String>>,
+    #[deserr(default, error = DeserrJsonError<InvalidSearchFacets>)] // TODO
+    pub sort_facet_values_by: Option<FacetValuesSort>,
     #[deserr(default, error = DeserrJsonError<InvalidSearchHighlightPreTag>, default = DEFAULT_HIGHLIGHT_PRE_TAG())]
     pub highlight_pre_tag: String,
     #[deserr(default, error = DeserrJsonError<InvalidSearchHighlightPostTag>, default = DEFAULT_HIGHLIGHT_POST_TAG())]
@@ -165,6 +169,7 @@ impl SearchQueryWithIndex {
             filter,
             sort,
             facets,
+            sort_facet_values_by,
             highlight_pre_tag,
             highlight_post_tag,
             crop_marker,
@@ -190,6 +195,7 @@ impl SearchQueryWithIndex {
                 filter,
                 sort,
                 facets,
+                sort_facet_values_by,
                 highlight_pre_tag,
                 highlight_post_tag,
                 crop_marker,
@@ -226,6 +232,26 @@ impl From<MatchingStrategy> for TermsMatchingStrategy {
     }
 }
 
+#[derive(Debug, Default, Clone, PartialEq, Eq, Deserr)]
+#[deserr(rename_all = camelCase)]
+pub enum FacetValuesSort {
+    /// Facet values are sorted by decreasing count.
+    /// The count is the number of records containing this facet value in the results of the query.
+    #[default]
+    Alpha,
+    /// Facet values are sorted in alphabetical order, ascending from A to Z.
+    Count,
+}
+
+impl Into<OrderBy> for FacetValuesSort {
+    fn into(self) -> OrderBy {
+        match self {
+            FacetValuesSort::Alpha => OrderBy::Lexicographic,
+            FacetValuesSort::Count => OrderBy::Count,
+        }
+    }
+}
+
 #[derive(Debug, Clone, Serialize, PartialEq)]
 pub struct SearchHit {
     #[serde(flatten)]
@@ -557,7 +583,10 @@ pub fn perform_search(
             if fields.iter().all(|f| f != "*") {
                 facet_distribution.facets(fields);
             }
-            let distribution = facet_distribution.candidates(candidates).execute()?;
+            let distribution = facet_distribution
+                .candidates(candidates)
+                .order_by(query.sort_facet_values_by.map_or_else(Default::default, Into::into))
+                .execute()?;
             let stats = facet_distribution.compute_stats()?;
             (Some(distribution), Some(stats))
         }

milli/src/lib.rs

@@ -58,7 +58,7 @@ pub use self::heed_codec::{
 pub use self::index::Index;
 pub use self::search::{
     FacetDistribution, FacetValueHit, Filter, FormatOptions, MatchBounds, MatcherBuilder,
-    MatchingWords, Search, SearchForFacetValues, SearchResult, TermsMatchingStrategy,
+    MatchingWords, OrderBy, Search, SearchForFacetValues, SearchResult, TermsMatchingStrategy,
     DEFAULT_VALUES_PER_FACET,
 };
 

milli/src/search/facet/facet_distribution.rs

@@ -12,11 +12,10 @@ use crate::heed_codec::facet::{
     FacetGroupKeyCodec, FieldDocIdFacetF64Codec, FieldDocIdFacetStringCodec, OrderedF64Codec,
 };
 use crate::heed_codec::{ByteSliceRefCodec, StrRefCodec};
-use crate::search::facet::facet_distribution_iter;
+use crate::search::facet::facet_distribution_iter::{
-use crate::{FieldId, Index, Result};
-use facet_distribution_iter::{
     count_iterate_over_facet_distribution, lexicographically_iterate_over_facet_distribution,
 };
+use crate::{FieldId, Index, Result};
 
 /// The default number of values by facets that will
 /// be fetched from the key-value store.
@@ -27,9 +26,10 @@ pub const DEFAULT_VALUES_PER_FACET: usize = 100;
 const CANDIDATES_THRESHOLD: u64 = 3000;
 
 /// How should we fetch the facets?
-#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+#[derive(Debug, Default, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub enum OrderBy {
     /// By lexicographic order...
+    #[default]
     Lexicographic,
     /// Or by number of docids in common?
     Count,
@@ -50,7 +50,7 @@ impl<'a> FacetDistribution<'a> {
             facets: None,
             candidates: None,
             max_values_per_facet: DEFAULT_VALUES_PER_FACET,
-            order_by: OrderBy::Count,
+            order_by: OrderBy::default(),
             rtxn,
             index,
         }

milli/src/search/facet/mod.rs

@@ -4,7 +4,7 @@ use heed::types::{ByteSlice, DecodeIgnore};
 use heed::{BytesDecode, RoTxn};
 use roaring::RoaringBitmap;
 
-pub use self::facet_distribution::{FacetDistribution, DEFAULT_VALUES_PER_FACET};
+pub use self::facet_distribution::{FacetDistribution, OrderBy, DEFAULT_VALUES_PER_FACET};
 pub use self::filter::{BadGeoError, Filter};
 use crate::heed_codec::facet::{FacetGroupKeyCodec, FacetGroupValueCodec, OrderedF64Codec};
 use crate::heed_codec::ByteSliceRefCodec;

milli/src/search/mod.rs

@@ -7,7 +7,7 @@ use log::error;
 use once_cell::sync::Lazy;
 use roaring::bitmap::RoaringBitmap;
 
-pub use self::facet::{FacetDistribution, Filter, DEFAULT_VALUES_PER_FACET};
+pub use self::facet::{FacetDistribution, Filter, OrderBy, DEFAULT_VALUES_PER_FACET};
 pub use self::new::matches::{FormatOptions, MatchBounds, Matcher, MatcherBuilder, MatchingWords};
 use self::new::PartialSearchResult;
 use crate::error::UserError;