Fix the tests

benchmarks/benches/utils.rs

@@ -12,7 +12,7 @@ use milli::heed::EnvOpenOptions;
 use milli::update::{
     IndexDocuments, IndexDocumentsConfig, IndexDocumentsMethod, IndexerConfig, Settings,
 };
-use milli::{Criterion, Filter, Index, Object, TermsMatchingStrategy};
+use milli::{Filter, Index, Object, RankingRule, TermsMatchingStrategy};
 use serde_json::Value;
 
 pub struct Conf<'a> {
@@ -78,11 +78,11 @@ pub fn base_setup(conf: &Conf) -> Index {
 
     if let Some(criterion) = conf.criterion {
         builder.reset_filterable_fields();
-        builder.reset_criteria();
+        builder.reset_ranking_rules();
         builder.reset_stop_words();
 
-        let criterion = criterion.iter().map(|s| Criterion::from_str(s).unwrap()).collect();
-        builder.set_criteria(criterion);
+        let criterion = criterion.iter().map(|s| RankingRule::from_str(s).unwrap()).collect();
+        builder.set_ranking_rules(criterion);
     }
 
     (conf.configure)(&mut builder);

meilisearch-types/src/settings.rs

@@ -9,7 +9,7 @@ use std::str::FromStr;
 use deserr::{DeserializeError, Deserr, ErrorKind, MergeWithError, ValuePointerRef};
 use fst::IntoStreamer;
 use milli::update::Setting;
-use milli::{Criterion, CriterionError, Index, DEFAULT_VALUES_PER_FACET};
+use milli::{Index, RankingRule, RankingRuleError, DEFAULT_VALUES_PER_FACET};
 use serde::{Deserialize, Serialize, Serializer};
 
 use crate::deserr::DeserrJsonError;
@@ -117,10 +117,10 @@ pub struct PaginationSettings {
     pub max_total_hits: Setting<usize>,
 }
 
-impl MergeWithError<milli::CriterionError> for DeserrJsonError<InvalidSettingsRankingRules> {
+impl MergeWithError<milli::RankingRuleError> for DeserrJsonError<InvalidSettingsRankingRules> {
     fn merge(
         _self_: Option<Self>,
-        other: milli::CriterionError,
+        other: milli::RankingRuleError,
         merge_location: ValuePointerRef,
     ) -> ControlFlow<Self, Self> {
         Self::error::<Infallible>(
@@ -344,9 +344,9 @@ pub fn apply_settings_to_builder(
 
     match settings.ranking_rules {
         Setting::Set(ref criteria) => {
-            builder.set_criteria(criteria.iter().map(|c| c.clone().into()).collect())
+            builder.set_ranking_rules(criteria.iter().map(|c| c.clone().into()).collect())
         }
-        Setting::Reset => builder.reset_criteria(),
+        Setting::Reset => builder.reset_ranking_rules(),
         Setting::NotSet => (),
     }
 
@@ -578,11 +578,13 @@ pub fn settings(
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Deserr)]
-#[deserr(try_from(&String) = FromStr::from_str -> CriterionError)]
+#[deserr(try_from(&String) = FromStr::from_str -> RankingRuleError)]
 pub enum RankingRuleView {
     /// Sorted by decreasing number of matched query terms.
     /// Query words at the front of an attribute is considered better than if it was at the back.
     Words,
+    /// Sorted by documents matching the given filter and then documents not matching it.
+    Boost(String),
     /// Sorted by increasing number of typos.
     Typo,
     /// Sorted by increasing distance between matched query terms.
@@ -605,7 +607,7 @@ impl Serialize for RankingRuleView {
     where
         S: Serializer,
     {
-        serializer.serialize_str(&format!("{}", Criterion::from(self.clone())))
+        serializer.serialize_str(&format!("{}", RankingRule::from(self.clone())))
     }
 }
 impl<'de> Deserialize<'de> for RankingRuleView {
@@ -623,7 +625,7 @@ impl<'de> Deserialize<'de> for RankingRuleView {
             where
                 E: serde::de::Error,
             {
-                let criterion = Criterion::from_str(v).map_err(|_| {
+                let criterion = RankingRule::from_str(v).map_err(|_| {
                     E::invalid_value(serde::de::Unexpected::Str(v), &"a valid ranking rule")
                 })?;
                 Ok(RankingRuleView::from(criterion))
@@ -633,42 +635,44 @@ impl<'de> Deserialize<'de> for RankingRuleView {
     }
 }
 impl FromStr for RankingRuleView {
-    type Err = <Criterion as FromStr>::Err;
+    type Err = <RankingRule as FromStr>::Err;
 
     fn from_str(s: &str) -> Result<Self, Self::Err> {
-        Ok(RankingRuleView::from(Criterion::from_str(s)?))
+        Ok(RankingRuleView::from(RankingRule::from_str(s)?))
     }
 }
 impl fmt::Display for RankingRuleView {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        fmt::Display::fmt(&Criterion::from(self.clone()), f)
+        fmt::Display::fmt(&RankingRule::from(self.clone()), f)
     }
 }
-impl From<Criterion> for RankingRuleView {
-    fn from(value: Criterion) -> Self {
+impl From<RankingRule> for RankingRuleView {
+    fn from(value: RankingRule) -> Self {
         match value {
-            Criterion::Words => RankingRuleView::Words,
-            Criterion::Typo => RankingRuleView::Typo,
-            Criterion::Proximity => RankingRuleView::Proximity,
-            Criterion::Attribute => RankingRuleView::Attribute,
-            Criterion::Sort => RankingRuleView::Sort,
-            Criterion::Exactness => RankingRuleView::Exactness,
-            Criterion::Asc(x) => RankingRuleView::Asc(x),
-            Criterion::Desc(x) => RankingRuleView::Desc(x),
+            RankingRule::Words => RankingRuleView::Words,
+            RankingRule::Boost(filter) => RankingRuleView::Boost(filter),
+            RankingRule::Typo => RankingRuleView::Typo,
+            RankingRule::Proximity => RankingRuleView::Proximity,
+            RankingRule::Attribute => RankingRuleView::Attribute,
+            RankingRule::Sort => RankingRuleView::Sort,
+            RankingRule::Exactness => RankingRuleView::Exactness,
+            RankingRule::Asc(x) => RankingRuleView::Asc(x),
+            RankingRule::Desc(x) => RankingRuleView::Desc(x),
         }
     }
 }
-impl From<RankingRuleView> for Criterion {
+impl From<RankingRuleView> for RankingRule {
     fn from(value: RankingRuleView) -> Self {
         match value {
-            RankingRuleView::Words => Criterion::Words,
-            RankingRuleView::Typo => Criterion::Typo,
-            RankingRuleView::Proximity => Criterion::Proximity,
-            RankingRuleView::Attribute => Criterion::Attribute,
-            RankingRuleView::Sort => Criterion::Sort,
-            RankingRuleView::Exactness => Criterion::Exactness,
-            RankingRuleView::Asc(x) => Criterion::Asc(x),
-            RankingRuleView::Desc(x) => Criterion::Desc(x),
+            RankingRuleView::Words => RankingRule::Words,
+            RankingRuleView::Boost(filter) => RankingRule::Boost(filter),
+            RankingRuleView::Typo => RankingRule::Typo,
+            RankingRuleView::Proximity => RankingRule::Proximity,
+            RankingRuleView::Attribute => RankingRule::Attribute,
+            RankingRuleView::Sort => RankingRule::Sort,
+            RankingRuleView::Exactness => RankingRule::Exactness,
+            RankingRuleView::Asc(x) => RankingRule::Asc(x),
+            RankingRuleView::Desc(x) => RankingRule::Desc(x),
         }
     }
 }

milli/examples/settings.rs

@@ -3,7 +3,7 @@ use heed::EnvOpenOptions;
 // use maplit::hashset;
 use milli::{
     update::{IndexerConfig, Settings},
-    Criterion, Index,
+    Index, RankingRule,
 };
 
 fn main() {
@@ -19,13 +19,13 @@ fn main() {
     // builder.set_min_word_len_one_typo(5);
     // builder.set_min_word_len_two_typos(7);
     // builder.set_sortable_fields(hashset! { S("release_date") });
-    builder.set_criteria(vec![
-        Criterion::Words,
-        Criterion::Typo,
-        Criterion::Proximity,
-        Criterion::Attribute,
-        Criterion::Sort,
-        Criterion::Exactness,
+    builder.set_ranking_rules(vec![
+        RankingRule::Words,
+        RankingRule::Typo,
+        RankingRule::Proximity,
+        RankingRule::Attribute,
+        RankingRule::Sort,
+        RankingRule::Exactness,
     ]);
 
     builder.execute(|_| (), || false).unwrap();

milli/src/asc_desc.rs

@@ -8,7 +8,7 @@ use thiserror::Error;
 
 use crate::error::is_reserved_keyword;
 use crate::search::facet::BadGeoError;
-use crate::{CriterionError, Error, UserError};
+use crate::{Error, RankingRuleError, UserError};
 
 /// This error type is never supposed to be shown to the end user.
 /// You must always cast it to a sort error or a criterion error.
@@ -28,23 +28,23 @@ impl From<BadGeoError> for AscDescError {
     }
 }
 
-impl From<AscDescError> for CriterionError {
+impl From<AscDescError> for RankingRuleError {
     fn from(error: AscDescError) -> Self {
         match error {
             AscDescError::GeoError(_) => {
-                CriterionError::ReservedNameForSort { name: "_geoPoint".to_string() }
+                RankingRuleError::ReservedNameForSort { name: "_geoPoint".to_string() }
             }
-            AscDescError::InvalidSyntax { name } => CriterionError::InvalidName { name },
+            AscDescError::InvalidSyntax { name } => RankingRuleError::InvalidName { name },
             AscDescError::ReservedKeyword { name } if name.starts_with("_geoPoint") => {
-                CriterionError::ReservedNameForSort { name: "_geoPoint".to_string() }
+                RankingRuleError::ReservedNameForSort { name: "_geoPoint".to_string() }
             }
             AscDescError::ReservedKeyword { name } if name.starts_with("_geoRadius") => {
-                CriterionError::ReservedNameForFilter { name: "_geoRadius".to_string() }
+                RankingRuleError::ReservedNameForFilter { name: "_geoRadius".to_string() }
             }
             AscDescError::ReservedKeyword { name } if name.starts_with("_geoBoundingBox") => {
-                CriterionError::ReservedNameForFilter { name: "_geoBoundingBox".to_string() }
+                RankingRuleError::ReservedNameForFilter { name: "_geoBoundingBox".to_string() }
             }
-            AscDescError::ReservedKeyword { name } => CriterionError::ReservedName { name },
+            AscDescError::ReservedKeyword { name } => RankingRuleError::ReservedName { name },
         }
     }
 }

milli/src/boost.rs

@@ -0,0 +1,38 @@
+//! This module provides the `Boost` type and defines all the errors related to this type.
+
+use std::str::FromStr;
+
+use serde::{Deserialize, Serialize};
+use thiserror::Error;
+
+use crate::RankingRuleError;
+
+/// This error type is never supposed to be shown to the end user.
+/// You must always cast it to a sort error or a criterion error.
+#[derive(Error, Debug)]
+pub enum BoostError {
+    #[error("Invalid syntax for the boost parameter: expected expression starting with `boost:`, found `{name}`.")]
+    InvalidSyntax { name: String },
+}
+
+impl From<BoostError> for RankingRuleError {
+    fn from(error: BoostError) -> Self {
+        match error {
+            BoostError::InvalidSyntax { name } => RankingRuleError::InvalidName { name },
+        }
+    }
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq)]
+pub struct Boost(pub String);
+
+impl FromStr for Boost {
+    type Err = BoostError;
+
+    fn from_str(text: &str) -> Result<Boost, Self::Err> {
+        match text.split_once(':') {
+            Some(("boost", right)) => Ok(Boost(right.to_string())), // TODO check filter validity
+            _ => Err(BoostError::InvalidSyntax { name: text.to_string() }),
+        }
+    }
+}

milli/src/error.rs

@@ -9,7 +9,7 @@ use serde_json::Value;
 use thiserror::Error;
 
 use crate::documents::{self, DocumentsBatchCursorError};
-use crate::{CriterionError, DocumentId, FieldId, Object, SortError};
+use crate::{DocumentId, FieldId, Object, RankingRuleError, SortError};
 
 pub fn is_reserved_keyword(keyword: &str) -> bool {
     ["_geo", "_geoDistance", "_geoPoint", "_geoRadius", "_geoBoundingBox"].contains(&keyword)
@@ -94,7 +94,7 @@ pub enum UserError {
     #[error("A document cannot contain more than 65,535 fields.")]
     AttributeLimitReached,
     #[error(transparent)]
-    CriterionError(#[from] CriterionError),
+    CriterionError(#[from] RankingRuleError),
     #[error("Maximum number of documents reached.")]
     DocumentLimitReached,
     #[error(
@@ -280,7 +280,7 @@ error_from_sub_error! {
     ThreadPoolBuildError => InternalError,
     SerializationError => InternalError,
     GeoError => UserError,
-    CriterionError => UserError,
+    RankingRuleError => UserError,
 }
 
 impl<E> From<grenad::Error<E>> for Error

milli/src/index.rs

@@ -25,10 +25,9 @@ use crate::heed_codec::{
 };
 use crate::readable_slices::ReadableSlices;
 use crate::{
-    default_criteria, CboRoaringBitmapCodec, Criterion, DocumentId, ExternalDocumentsIds,
-    FacetDistribution, FieldDistribution, FieldId, FieldIdWordCountCodec, GeoPoint, ObkvCodec,
-    OrderBy, Result, RoaringBitmapCodec, RoaringBitmapLenCodec, Search, U8StrStrCodec, BEU16,
-    BEU32,
+    default_criteria, CboRoaringBitmapCodec, DocumentId, ExternalDocumentsIds, FacetDistribution,
+    FieldDistribution, FieldId, FieldIdWordCountCodec, GeoPoint, ObkvCodec, OrderBy, RankingRule,
+    Result, RoaringBitmapCodec, RoaringBitmapLenCodec, Search, U8StrStrCodec, BEU16, BEU32,
 };
 
 /// The HNSW data-structure that we serialize, fill and search in.
@@ -895,7 +894,7 @@ impl Index {
         let distinct_field = self.distinct_field(rtxn)?;
         let asc_desc_fields =
             self.criteria(rtxn)?.into_iter().filter_map(|criterion| match criterion {
-                Criterion::Asc(field) | Criterion::Desc(field) => Some(field),
+                RankingRule::Asc(field) | RankingRule::Desc(field) => Some(field),
                 _otherwise => None,
             });
 
@@ -1023,17 +1022,17 @@ impl Index {
     pub(crate) fn put_criteria(
         &self,
         wtxn: &mut RwTxn,
-        criteria: &[Criterion],
+        criteria: &[RankingRule],
     ) -> heed::Result<()> {
-        self.main.put::<_, Str, SerdeJson<&[Criterion]>>(wtxn, main_key::CRITERIA_KEY, &criteria)
+        self.main.put::<_, Str, SerdeJson<&[RankingRule]>>(wtxn, main_key::CRITERIA_KEY, &criteria)
     }
 
     pub(crate) fn delete_criteria(&self, wtxn: &mut RwTxn) -> heed::Result<bool> {
         self.main.delete::<_, Str>(wtxn, main_key::CRITERIA_KEY)
     }
 
-    pub fn criteria(&self, rtxn: &RoTxn) -> heed::Result<Vec<Criterion>> {
-        match self.main.get::<_, Str, SerdeJson<Vec<Criterion>>>(rtxn, main_key::CRITERIA_KEY)? {
+    pub fn criteria(&self, rtxn: &RoTxn) -> heed::Result<Vec<RankingRule>> {
+        match self.main.get::<_, Str, SerdeJson<Vec<RankingRule>>>(rtxn, main_key::CRITERIA_KEY)? {
             Some(criteria) => Ok(criteria),
             None => Ok(default_criteria()),
         }

milli/src/lib.rs

@@ -9,7 +9,7 @@ pub static ALLOC: mimalloc::MiMalloc = mimalloc::MiMalloc;
 pub mod documents;
 
 mod asc_desc;
-mod criterion;
+mod boost;
 pub mod distance;
 mod error;
 mod external_documents_ids;
@@ -18,6 +18,7 @@ mod fields_ids_map;
 pub mod heed_codec;
 pub mod index;
 pub mod proximity;
+mod ranking_rule;
 mod readable_slices;
 pub mod score_details;
 mod search;
@@ -44,7 +45,6 @@ use serde_json::Value;
 pub use {charabia as tokenizer, heed};
 
 pub use self::asc_desc::{AscDesc, AscDescError, Member, SortError};
-pub use self::criterion::{default_criteria, Criterion, CriterionError};
 pub use self::error::{
     Error, FieldIdMapMissingEntry, InternalError, SerializationError, UserError,
 };
@@ -57,6 +57,7 @@ pub use self::heed_codec::{
     UncheckedU8StrStrCodec,
 };
 pub use self::index::Index;
+pub use self::ranking_rule::{default_criteria, RankingRule, RankingRuleError};
 pub use self::search::{
     FacetDistribution, FacetValueHit, Filter, FormatOptions, MatchBounds, MatcherBuilder,
     MatchingWords, OrderBy, Search, SearchForFacetValues, SearchResult, TermsMatchingStrategy,

milli/src/ranking_rule.rs

@@ -4,10 +4,11 @@ use std::str::FromStr;
 use serde::{Deserialize, Serialize};
 use thiserror::Error;
 
-use crate::{AscDesc, Member};
+use crate::boost::{Boost, BoostError};
+use crate::{AscDesc, AscDescError, Member};
 
 #[derive(Error, Debug)]
-pub enum CriterionError {
+pub enum RankingRuleError {
     #[error("`{name}` ranking rule is invalid. Valid ranking rules are words, typo, sort, proximity, attribute, exactness and custom ranking rules.")]
     InvalidName { name: String },
     #[error("`{name}` is a reserved keyword and thus can't be used as a ranking rule")]
@@ -25,10 +26,12 @@ pub enum CriterionError {
 }
 
 #[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Eq)]
-pub enum Criterion {
+pub enum RankingRule {
     /// Sorted by decreasing number of matched query terms.
     /// Query words at the front of an attribute is considered better than if it was at the back.
     Words,
+    /// Sorted by documents matching the given filter and then documents not matching it.
+    Boost(String),
     /// Sorted by increasing number of typos.
     Typo,
     /// Sorted by increasing distance between matched query terms.
@@ -47,62 +50,76 @@ pub enum Criterion {
     Desc(String),
 }
 
-impl Criterion {
+impl RankingRule {
     /// Returns the field name parameter of this criterion.
     pub fn field_name(&self) -> Option<&str> {
         match self {
-            Criterion::Asc(name) | Criterion::Desc(name) => Some(name),
+            RankingRule::Asc(name) | RankingRule::Desc(name) => Some(name),
             _otherwise => None,
         }
     }
 }
 
-impl FromStr for Criterion {
-    type Err = CriterionError;
+impl FromStr for RankingRule {
+    type Err = RankingRuleError;
 
-    fn from_str(text: &str) -> Result<Criterion, Self::Err> {
+    fn from_str(text: &str) -> Result<RankingRule, Self::Err> {
         match text {
-            "words" => Ok(Criterion::Words),
-            "typo" => Ok(Criterion::Typo),
-            "proximity" => Ok(Criterion::Proximity),
-            "attribute" => Ok(Criterion::Attribute),
-            "sort" => Ok(Criterion::Sort),
-            "exactness" => Ok(Criterion::Exactness),
-            text => match AscDesc::from_str(text)? {
-                AscDesc::Asc(Member::Field(field)) => Ok(Criterion::Asc(field)),
-                AscDesc::Desc(Member::Field(field)) => Ok(Criterion::Desc(field)),
-                AscDesc::Asc(Member::Geo(_)) | AscDesc::Desc(Member::Geo(_)) => {
-                    Err(CriterionError::ReservedNameForSort { name: "_geoPoint".to_string() })?
-                }
+            "words" => Ok(RankingRule::Words),
+            "typo" => Ok(RankingRule::Typo),
+            "proximity" => Ok(RankingRule::Proximity),
+            "attribute" => Ok(RankingRule::Attribute),
+            "sort" => Ok(RankingRule::Sort),
+            "exactness" => Ok(RankingRule::Exactness),
+            text => match (AscDesc::from_str(text), Boost::from_str(text)) {
+                (Ok(asc_desc), _) => match asc_desc {
+                    AscDesc::Asc(Member::Field(field)) => Ok(RankingRule::Asc(field)),
+                    AscDesc::Desc(Member::Field(field)) => Ok(RankingRule::Desc(field)),
+                    AscDesc::Asc(Member::Geo(_)) | AscDesc::Desc(Member::Geo(_)) => {
+                        Err(RankingRuleError::ReservedNameForSort {
+                            name: "_geoPoint".to_string(),
+                        })?
+                    }
+                },
+                (_, Ok(Boost(filter))) => Ok(RankingRule::Boost(filter)),
+                (
+                    Err(AscDescError::InvalidSyntax { name: asc_desc_name }),
+                    Err(BoostError::InvalidSyntax { name: boost_name }),
+                ) => Err(RankingRuleError::InvalidName {
+                    // TODO improve the error message quality
+                    name: format!("{asc_desc_name} {boost_name}"),
+                }),
+                (Err(asc_desc_error), _) => Err(asc_desc_error.into()),
             },
         }
     }
 }
 
-pub fn default_criteria() -> Vec<Criterion> {
+pub fn default_criteria() -> Vec<RankingRule> {
     vec![
-        Criterion::Words,
-        Criterion::Typo,
-        Criterion::Proximity,
-        Criterion::Attribute,
-        Criterion::Sort,
-        Criterion::Exactness,
+        RankingRule::Words,
+        RankingRule::Typo,
+        RankingRule::Proximity,
+        RankingRule::Attribute,
+        RankingRule::Sort,
+        RankingRule::Exactness,
     ]
 }
 
-impl fmt::Display for Criterion {
+impl fmt::Display for RankingRule {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        use Criterion::*;
+        use RankingRule::*;
 
         match self {
             Words => f.write_str("words"),
+            Boost(filter) => write!(f, "boost:{filter}"),
             Typo => f.write_str("typo"),
             Proximity => f.write_str("proximity"),
             Attribute => f.write_str("attribute"),
             Sort => f.write_str("sort"),
             Exactness => f.write_str("exactness"),
-            Asc(attr) => write!(f, "{}:asc", attr),
-            Desc(attr) => write!(f, "{}:desc", attr),
+            Asc(attr) => write!(f, "{attr}:asc"),
+            Desc(attr) => write!(f, "{attr}:desc"),
         }
     }
 }
@@ -110,29 +127,29 @@ impl fmt::Display for Criterion {
 #[cfg(test)]
 mod tests {
     use big_s::S;
-    use CriterionError::*;
+    use RankingRuleError::*;
 
     use super::*;
 
     #[test]
     fn parse_criterion() {
         let valid_criteria = [
-            ("words", Criterion::Words),
-            ("typo", Criterion::Typo),
-            ("proximity", Criterion::Proximity),
-            ("attribute", Criterion::Attribute),
-            ("sort", Criterion::Sort),
-            ("exactness", Criterion::Exactness),
-            ("price:asc", Criterion::Asc(S("price"))),
-            ("price:desc", Criterion::Desc(S("price"))),
-            ("price:asc:desc", Criterion::Desc(S("price:asc"))),
-            ("truc:machin:desc", Criterion::Desc(S("truc:machin"))),
-            ("hello-world!:desc", Criterion::Desc(S("hello-world!"))),
-            ("it's spacy over there:asc", Criterion::Asc(S("it's spacy over there"))),
+            ("words", RankingRule::Words),
+            ("typo", RankingRule::Typo),
+            ("proximity", RankingRule::Proximity),
+            ("attribute", RankingRule::Attribute),
+            ("sort", RankingRule::Sort),
+            ("exactness", RankingRule::Exactness),
+            ("price:asc", RankingRule::Asc(S("price"))),
+            ("price:desc", RankingRule::Desc(S("price"))),
+            ("price:asc:desc", RankingRule::Desc(S("price:asc"))),
+            ("truc:machin:desc", RankingRule::Desc(S("truc:machin"))),
+            ("hello-world!:desc", RankingRule::Desc(S("hello-world!"))),
+            ("it's spacy over there:asc", RankingRule::Asc(S("it's spacy over there"))),
         ];
 
         for (input, expected) in valid_criteria {
-            let res = input.parse::<Criterion>();
+            let res = input.parse::<RankingRule>();
             assert!(
                 res.is_ok(),
                 "Failed to parse `{}`, was expecting `{:?}` but instead got `{:?}`",
@@ -167,7 +184,7 @@ mod tests {
         ];
 
         for (input, expected) in invalid_criteria {
-            let res = input.parse::<Criterion>();
+            let res = input.parse::<RankingRule>();
             assert!(
                 res.is_err(),
                 "Should no be able to parse `{}`, was expecting an error but instead got: `{:?}`",

milli/src/score_details.rs

@@ -5,6 +5,7 @@ use crate::distance_between_two_points;
 #[derive(Debug, Clone, PartialEq)]
 pub enum ScoreDetails {
     Words(Words),
+    Boost(Boost),
     Typo(Typo),
     Proximity(Rank),
     Fid(Rank),
@@ -23,6 +24,7 @@ impl ScoreDetails {
     pub fn rank(&self) -> Option<Rank> {
         match self {
             ScoreDetails::Words(details) => Some(details.rank()),
+            ScoreDetails::Boost(_) => None,
             ScoreDetails::Typo(details) => Some(details.rank()),
             ScoreDetails::Proximity(details) => Some(*details),
             ScoreDetails::Fid(details) => Some(*details),
@@ -60,6 +62,14 @@ impl ScoreDetails {
                     details_map.insert("words".into(), words_details);
                     order += 1;
                 }
+                ScoreDetails::Boost(Boost { filter, matching }) => {
+                    let sort = format!("boost:{}", filter);
+                    let sort_details = serde_json::json!({
+                        "value": matching,
+                    });
+                    details_map.insert(sort, sort_details);
+                    order += 1;
+                }
                 ScoreDetails::Typo(typo) => {
                     let typo_details = serde_json::json!({
                         "order": order,
@@ -221,6 +231,12 @@ impl Words {
     }
 }
 
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct Boost {
+    pub filter: String,
+    pub matching: bool,
+}
+
 /// Structure that is super similar to [`Words`], but whose semantics is a bit distinct.
 ///
 /// In exactness, the number of matching words can actually be 0 with a non-zero score,

milli/src/search/new/boost.rs

@@ -0,0 +1,88 @@
+use roaring::RoaringBitmap;
+
+use super::logger::SearchLogger;
+use super::{RankingRule, RankingRuleOutput, RankingRuleQueryTrait, SearchContext};
+use crate::score_details::{self, ScoreDetails};
+use crate::{Filter, Result};
+
+pub struct Boost<Query> {
+    original_expression: String,
+    original_query: Option<Query>,
+    matching: Option<RankingRuleOutput<Query>>,
+    non_matching: Option<RankingRuleOutput<Query>>,
+}
+
+impl<Query> Boost<Query> {
+    pub fn new(expression: String) -> Result<Self> {
+        Ok(Self {
+            original_expression: expression,
+            original_query: None,
+            matching: None,
+            non_matching: None,
+        })
+    }
+}
+
+impl<'ctx, Query: RankingRuleQueryTrait> RankingRule<'ctx, Query> for Boost<Query> {
+    fn id(&self) -> String {
+        // TODO improve this
+        let Self { original_expression, .. } = self;
+        format!("boost:{original_expression}")
+    }
+
+    fn start_iteration(
+        &mut self,
+        ctx: &mut SearchContext<'ctx>,
+        _logger: &mut dyn SearchLogger<Query>,
+        parent_candidates: &RoaringBitmap,
+        parent_query: &Query,
+    ) -> Result<()> {
+        let universe_matching = match Filter::from_str(&self.original_expression)? {
+            Some(filter) => filter.evaluate(ctx.txn, ctx.index)?,
+            None => RoaringBitmap::default(),
+        };
+        let matching = parent_candidates & universe_matching;
+        let non_matching = parent_candidates - &matching;
+
+        self.original_query = Some(parent_query.clone());
+
+        self.matching = Some(RankingRuleOutput {
+            query: parent_query.clone(),
+            candidates: matching,
+            score: ScoreDetails::Boost(score_details::Boost {
+                filter: self.original_expression.clone(),
+                matching: true,
+            }),
+        });
+
+        self.non_matching = Some(RankingRuleOutput {
+            query: parent_query.clone(),
+            candidates: non_matching,
+            score: ScoreDetails::Boost(score_details::Boost {
+                filter: self.original_expression.clone(),
+                matching: false,
+            }),
+        });
+
+        Ok(())
+    }
+
+    fn next_bucket(
+        &mut self,
+        _ctx: &mut SearchContext<'ctx>,
+        _logger: &mut dyn SearchLogger<Query>,
+        _universe: &RoaringBitmap,
+    ) -> Result<Option<RankingRuleOutput<Query>>> {
+        Ok(self.matching.take().or_else(|| self.non_matching.take()))
+    }
+
+    fn end_iteration(
+        &mut self,
+        _ctx: &mut SearchContext<'ctx>,
+        _logger: &mut dyn SearchLogger<Query>,
+    ) {
+        self.original_query = None;
+        self.matching = None;
+        self.non_matching = None;
+    }
+}

milli/src/search/new/mod.rs

@@ -14,6 +14,7 @@ mod ranking_rules;
 mod resolve_query_graph;
 mod small_bitmap;
 
+mod boost;
 mod exact_attribute;
 mod sort;
 
@@ -22,6 +23,7 @@ mod tests;
 
 use std::collections::HashSet;
 
+use boost::Boost;
 use bucket_sort::{bucket_sort, BucketSortOutput};
 use charabia::TokenizerBuilder;
 use db_cache::DatabaseCache;
@@ -203,12 +205,13 @@ fn get_ranking_rules_for_placeholder_search<'ctx>(
     for rr in settings_ranking_rules {
         match rr {
             // These rules need a query to have an effect; ignore them in placeholder search
-            crate::Criterion::Words
-            | crate::Criterion::Typo
-            | crate::Criterion::Attribute
-            | crate::Criterion::Proximity
-            | crate::Criterion::Exactness => continue,
-            crate::Criterion::Sort => {
+            crate::RankingRule::Words
+            | crate::RankingRule::Typo
+            | crate::RankingRule::Attribute
+            | crate::RankingRule::Proximity
+            | crate::RankingRule::Exactness => continue,
+            crate::RankingRule::Boost(filter) => ranking_rules.push(Box::new(Boost::new(filter)?)),
+            crate::RankingRule::Sort => {
                 if sort {
                     continue;
                 }
@@ -222,14 +225,14 @@ fn get_ranking_rules_for_placeholder_search<'ctx>(
                 )?;
                 sort = true;
             }
-            crate::Criterion::Asc(field_name) => {
+            crate::RankingRule::Asc(field_name) => {
                 if sorted_fields.contains(&field_name) {
                     continue;
                 }
                 sorted_fields.insert(field_name.clone());
                 ranking_rules.push(Box::new(Sort::new(ctx.index, ctx.txn, field_name, true)?));
             }
-            crate::Criterion::Desc(field_name) => {
+            crate::RankingRule::Desc(field_name) => {
                 if sorted_fields.contains(&field_name) {
                     continue;
                 }
@@ -268,10 +271,10 @@ fn get_ranking_rules_for_query_graph_search<'ctx>(
     for rr in settings_ranking_rules {
         // Add Words before any of: typo, proximity, attribute
         match rr {
-            crate::Criterion::Typo
-            | crate::Criterion::Attribute
-            | crate::Criterion::Proximity
-            | crate::Criterion::Exactness => {
+            crate::RankingRule::Typo
+            | crate::RankingRule::Attribute
+            | crate::RankingRule::Proximity
+            | crate::RankingRule::Exactness => {
                 if !words {
                     ranking_rules.push(Box::new(Words::new(terms_matching_strategy)));
                     words = true;
@@ -280,28 +283,31 @@ fn get_ranking_rules_for_query_graph_search<'ctx>(
             _ => {}
         }
         match rr {
-            crate::Criterion::Words => {
+            crate::RankingRule::Words => {
                 if words {
                     continue;
                 }
                 ranking_rules.push(Box::new(Words::new(terms_matching_strategy)));
                 words = true;
             }
-            crate::Criterion::Typo => {
+            crate::RankingRule::Boost(filter) => {
+                ranking_rules.push(Box::new(Boost::new(filter)?));
+            }
+            crate::RankingRule::Typo => {
                 if typo {
                     continue;
                 }
                 typo = true;
                 ranking_rules.push(Box::new(Typo::new(None)));
             }
-            crate::Criterion::Proximity => {
+            crate::RankingRule::Proximity => {
                 if proximity {
                     continue;
                 }
                 proximity = true;
                 ranking_rules.push(Box::new(Proximity::new(None)));
             }
-            crate::Criterion::Attribute => {
+            crate::RankingRule::Attribute => {
                 if attribute {
                     continue;
                 }
@@ -309,7 +315,7 @@ fn get_ranking_rules_for_query_graph_search<'ctx>(
                 ranking_rules.push(Box::new(Fid::new(None)));
                 ranking_rules.push(Box::new(Position::new(None)));
             }
-            crate::Criterion::Sort => {
+            crate::RankingRule::Sort => {
                 if sort {
                     continue;
                 }
@@ -323,7 +329,7 @@ fn get_ranking_rules_for_query_graph_search<'ctx>(
                 )?;
                 sort = true;
             }
-            crate::Criterion::Exactness => {
+            crate::RankingRule::Exactness => {
                 if exactness {
                     continue;
                 }
@@ -331,14 +337,15 @@ fn get_ranking_rules_for_query_graph_search<'ctx>(
                 ranking_rules.push(Box::new(Exactness::new()));
                 exactness = true;
             }
-            crate::Criterion::Asc(field_name) => {
+            crate::RankingRule::Asc(field_name) => {
+                // TODO Question: Why would it be invalid to sort price:asc, typo, price:desc?
                 if sorted_fields.contains(&field_name) {
                     continue;
                 }
                 sorted_fields.insert(field_name.clone());
                 ranking_rules.push(Box::new(Sort::new(ctx.index, ctx.txn, field_name, true)?));
             }
-            crate::Criterion::Desc(field_name) => {
+            crate::RankingRule::Desc(field_name) => {
                 if sorted_fields.contains(&field_name) {
                     continue;
                 }
@@ -580,7 +587,8 @@ fn check_sort_criteria(ctx: &SearchContext, sort_criteria: Option<&Vec<AscDesc>>
 
     // We check that the sort ranking rule exists and throw an
     // error if we try to use it and that it doesn't.
-    let sort_ranking_rule_missing = !ctx.index.criteria(ctx.txn)?.contains(&crate::Criterion::Sort);
+    let sort_ranking_rule_missing =
+        !ctx.index.criteria(ctx.txn)?.contains(&crate::RankingRule::Sort);
     if sort_ranking_rule_missing {
         return Err(UserError::SortRankingRuleMissing.into());
     }

milli/src/search/new/tests/attribute_fid.rs

@@ -1,5 +1,5 @@
 use crate::index::tests::TempIndex;
-use crate::{Criterion, Search, SearchResult, TermsMatchingStrategy};
+use crate::{RankingRule, Search, SearchResult, TermsMatchingStrategy};
 
 fn create_index() -> TempIndex {
     let index = TempIndex::new();
@@ -12,7 +12,7 @@ fn create_index() -> TempIndex {
                 "description".to_owned(),
                 "plot".to_owned(),
             ]);
-            s.set_criteria(vec![Criterion::Attribute]);
+            s.set_ranking_rules(vec![RankingRule::Attribute]);
         })
         .unwrap();
 

milli/src/search/new/tests/attribute_position.rs

@@ -1,5 +1,5 @@
 use crate::index::tests::TempIndex;
-use crate::{db_snap, Criterion, Search, SearchResult, TermsMatchingStrategy};
+use crate::{db_snap, RankingRule, Search, SearchResult, TermsMatchingStrategy};
 
 fn create_index() -> TempIndex {
     let index = TempIndex::new();
@@ -12,7 +12,7 @@ fn create_index() -> TempIndex {
                 "text2".to_owned(),
                 "other".to_owned(),
             ]);
-            s.set_criteria(vec![Criterion::Attribute]);
+            s.set_ranking_rules(vec![RankingRule::Attribute]);
         })
         .unwrap();
 

milli/src/search/new/tests/distinct.rs

@@ -19,7 +19,7 @@ use maplit::hashset;
 
 use super::collect_field_values;
 use crate::index::tests::TempIndex;
-use crate::{AscDesc, Criterion, Index, Member, Search, SearchResult, TermsMatchingStrategy};
+use crate::{AscDesc, Index, Member, RankingRule, Search, SearchResult, TermsMatchingStrategy};
 
 fn create_index() -> TempIndex {
     let index = TempIndex::new();
@@ -30,7 +30,7 @@ fn create_index() -> TempIndex {
             s.set_searchable_fields(vec!["text".to_owned()]);
             s.set_sortable_fields(hashset! { S("rank1"), S("letter") });
             s.set_distinct_field("letter".to_owned());
-            s.set_criteria(vec![Criterion::Words]);
+            s.set_ranking_rules(vec![RankingRule::Words]);
         })
         .unwrap();
 
@@ -252,7 +252,7 @@ fn test_distinct_placeholder_sort() {
     let index = create_index();
     index
         .update_settings(|s| {
-            s.set_criteria(vec![Criterion::Sort]);
+            s.set_ranking_rules(vec![RankingRule::Sort]);
         })
         .unwrap();
 
@@ -387,7 +387,7 @@ fn test_distinct_words() {
     let index = create_index();
     index
         .update_settings(|s| {
-            s.set_criteria(vec![Criterion::Words]);
+            s.set_ranking_rules(vec![RankingRule::Words]);
         })
         .unwrap();
 
@@ -440,7 +440,11 @@ fn test_distinct_sort_words() {
     let index = create_index();
     index
         .update_settings(|s| {
-            s.set_criteria(vec![Criterion::Sort, Criterion::Words, Criterion::Desc(S("rank1"))]);
+            s.set_ranking_rules(vec![
+                RankingRule::Sort,
+                RankingRule::Words,
+                RankingRule::Desc(S("rank1")),
+            ]);
         })
         .unwrap();
 
@@ -513,7 +517,7 @@ fn test_distinct_all_candidates() {
     let index = create_index();
     index
         .update_settings(|s| {
-            s.set_criteria(vec![Criterion::Sort]);
+            s.set_ranking_rules(vec![RankingRule::Sort]);
         })
         .unwrap();
 
@@ -536,7 +540,7 @@ fn test_distinct_typo() {
     let index = create_index();
     index
         .update_settings(|s| {
-            s.set_criteria(vec![Criterion::Words, Criterion::Typo]);
+            s.set_ranking_rules(vec![RankingRule::Words, RankingRule::Typo]);
         })
         .unwrap();
 

milli/src/search/new/tests/exactness.rs

@@ -21,7 +21,7 @@ Then these rules will only work with
 
 use crate::index::tests::TempIndex;
 use crate::search::new::tests::collect_field_values;
-use crate::{Criterion, Search, SearchResult, TermsMatchingStrategy};
+use crate::{RankingRule, Search, SearchResult, TermsMatchingStrategy};
 
 fn create_index_simple_ordered() -> TempIndex {
     let index = TempIndex::new();
@@ -30,7 +30,7 @@ fn create_index_simple_ordered() -> TempIndex {
         .update_settings(|s| {
             s.set_primary_key("id".to_owned());
             s.set_searchable_fields(vec!["text".to_owned()]);
-            s.set_criteria(vec![Criterion::Exactness]);
+            s.set_ranking_rules(vec![RankingRule::Exactness]);
         })
         .unwrap();
 
@@ -89,7 +89,7 @@ fn create_index_simple_reversed() -> TempIndex {
         .update_settings(|s| {
             s.set_primary_key("id".to_owned());
             s.set_searchable_fields(vec!["text".to_owned()]);
-            s.set_criteria(vec![Criterion::Exactness]);
+            s.set_ranking_rules(vec![RankingRule::Exactness]);
         })
         .unwrap();
 
@@ -147,7 +147,7 @@ fn create_index_simple_random() -> TempIndex {
         .update_settings(|s| {
             s.set_primary_key("id".to_owned());
             s.set_searchable_fields(vec!["text".to_owned()]);
-            s.set_criteria(vec![Criterion::Exactness]);
+            s.set_ranking_rules(vec![RankingRule::Exactness]);
         })
         .unwrap();
 
@@ -201,7 +201,7 @@ fn create_index_attribute_starts_with() -> TempIndex {
         .update_settings(|s| {
             s.set_primary_key("id".to_owned());
             s.set_searchable_fields(vec!["text".to_owned()]);
-            s.set_criteria(vec![Criterion::Exactness]);
+            s.set_ranking_rules(vec![RankingRule::Exactness]);
         })
         .unwrap();
 
@@ -251,7 +251,7 @@ fn create_index_simple_ordered_with_typos() -> TempIndex {
         .update_settings(|s| {
             s.set_primary_key("id".to_owned());
             s.set_searchable_fields(vec!["text".to_owned()]);
-            s.set_criteria(vec![Criterion::Exactness]);
+            s.set_ranking_rules(vec![RankingRule::Exactness]);
         })
         .unwrap();
 
@@ -350,7 +350,11 @@ fn create_index_with_varying_proximities() -> TempIndex {
         .update_settings(|s| {
             s.set_primary_key("id".to_owned());
             s.set_searchable_fields(vec!["text".to_owned()]);
-            s.set_criteria(vec![Criterion::Exactness, Criterion::Words, Criterion::Proximity]);
+            s.set_ranking_rules(vec![
+                RankingRule::Exactness,
+                RankingRule::Words,
+                RankingRule::Proximity,
+            ]);
         })
         .unwrap();
 
@@ -404,7 +408,7 @@ fn create_index_with_typo_and_prefix() -> TempIndex {
         .update_settings(|s| {
             s.set_primary_key("id".to_owned());
             s.set_searchable_fields(vec!["text".to_owned()]);
-            s.set_criteria(vec![Criterion::Exactness]);
+            s.set_ranking_rules(vec![RankingRule::Exactness]);
         })
         .unwrap();
 
@@ -442,7 +446,11 @@ fn create_index_all_equal_except_proximity_between_ignored_terms() -> TempIndex
         .update_settings(|s| {
             s.set_primary_key("id".to_owned());
             s.set_searchable_fields(vec!["text".to_owned()]);
-            s.set_criteria(vec![Criterion::Exactness, Criterion::Words, Criterion::Proximity]);
+            s.set_ranking_rules(vec![
+                RankingRule::Exactness,
+                RankingRule::Words,
+                RankingRule::Proximity,
+            ]);
         })
         .unwrap();
 
@@ -698,7 +706,7 @@ fn test_exactness_after_words() {
 
     index
         .update_settings(|s| {
-            s.set_criteria(vec![Criterion::Words, Criterion::Exactness]);
+            s.set_ranking_rules(vec![RankingRule::Words, RankingRule::Exactness]);
         })
         .unwrap();
 
@@ -747,7 +755,7 @@ fn test_words_after_exactness() {
 
     index
         .update_settings(|s| {
-            s.set_criteria(vec![Criterion::Exactness, Criterion::Words]);
+            s.set_ranking_rules(vec![RankingRule::Exactness, RankingRule::Words]);
         })
         .unwrap();
 
@@ -796,7 +804,11 @@ fn test_proximity_after_exactness() {
 
     index
         .update_settings(|s| {
-            s.set_criteria(vec![Criterion::Exactness, Criterion::Words, Criterion::Proximity]);
+            s.set_ranking_rules(vec![
+                RankingRule::Exactness,
+                RankingRule::Words,
+                RankingRule::Proximity,
+            ]);
         })
         .unwrap();
 
@@ -834,7 +846,11 @@ fn test_proximity_after_exactness() {
 
     index
         .update_settings(|s| {
-            s.set_criteria(vec![Criterion::Exactness, Criterion::Words, Criterion::Proximity]);
+            s.set_ranking_rules(vec![
+                RankingRule::Exactness,
+                RankingRule::Words,
+                RankingRule::Proximity,
+            ]);
         })
         .unwrap();
 
@@ -868,7 +884,11 @@ fn test_exactness_followed_by_typo_prefer_no_typo_prefix() {
 
     index
         .update_settings(|s| {
-            s.set_criteria(vec![Criterion::Exactness, Criterion::Words, Criterion::Typo]);
+            s.set_ranking_rules(vec![
+                RankingRule::Exactness,
+                RankingRule::Words,
+                RankingRule::Typo,
+            ]);
         })
         .unwrap();
 
@@ -904,7 +924,11 @@ fn test_typo_followed_by_exactness() {
 
     index
         .update_settings(|s| {
-            s.set_criteria(vec![Criterion::Words, Criterion::Typo, Criterion::Exactness]);
+            s.set_ranking_rules(vec![
+                RankingRule::Words,
+                RankingRule::Typo,
+                RankingRule::Exactness,
+            ]);
         })
         .unwrap();
 

milli/src/search/new/tests/geo_sort.rs

@@ -9,7 +9,7 @@ use maplit::hashset;
 use crate::index::tests::TempIndex;
 use crate::score_details::ScoreDetails;
 use crate::search::new::tests::collect_field_values;
-use crate::{AscDesc, Criterion, GeoSortStrategy, Member, Search, SearchResult};
+use crate::{AscDesc, GeoSortStrategy, Member, RankingRule, Search, SearchResult};
 
 fn create_index() -> TempIndex {
     let index = TempIndex::new();
@@ -18,7 +18,7 @@ fn create_index() -> TempIndex {
         .update_settings(|s| {
             s.set_primary_key("id".to_owned());
             s.set_sortable_fields(hashset! { S("_geo") });
-            s.set_criteria(vec![Criterion::Words, Criterion::Sort]);
+            s.set_ranking_rules(vec![RankingRule::Words, RankingRule::Sort]);
         })
         .unwrap();
     index

milli/src/search/new/tests/integration.rs

@@ -6,10 +6,10 @@ use maplit::{btreemap, hashset};
 
 use crate::documents::{DocumentsBatchBuilder, DocumentsBatchReader};
 use crate::update::{IndexDocuments, IndexDocumentsConfig, IndexerConfig, Settings};
-use crate::{db_snap, Criterion, Index, Object};
+use crate::{db_snap, Index, Object, RankingRule};
 pub const CONTENT: &str = include_str!("../../../../tests/assets/test_set.ndjson");
 
-pub fn setup_search_index_with_criteria(criteria: &[Criterion]) -> Index {
+pub fn setup_search_index_with_criteria(criteria: &[RankingRule]) -> Index {
     let path = tempfile::tempdir().unwrap();
     let mut options = EnvOpenOptions::new();
     options.map_size(10 * 1024 * 1024); // 10 MB
@@ -20,7 +20,7 @@ pub fn setup_search_index_with_criteria(criteria: &[Criterion]) -> Index {
 
     let mut builder = Settings::new(&mut wtxn, &index, &config);
 
-    builder.set_criteria(criteria.to_vec());
+    builder.set_ranking_rules(criteria.to_vec());
     builder.set_filterable_fields(hashset! {
         S("tag"),
         S("asc_desc_rank"),
@@ -70,6 +70,6 @@ pub fn setup_search_index_with_criteria(criteria: &[Criterion]) -> Index {
 
 #[test]
 fn snapshot_integration_dataset() {
-    let index = setup_search_index_with_criteria(&[Criterion::Attribute]);
+    let index = setup_search_index_with_criteria(&[RankingRule::Attribute]);
     db_snap!(index, word_position_docids, @"3c9347a767bceef3beb31465f1e5f3ae");
 }

milli/src/search/new/tests/ngram_split_words.rs

@@ -19,7 +19,7 @@ This module tests the following properties:
 
 use crate::index::tests::TempIndex;
 use crate::search::new::tests::collect_field_values;
-use crate::{Criterion, Search, SearchResult, TermsMatchingStrategy};
+use crate::{RankingRule, Search, SearchResult, TermsMatchingStrategy};
 
 fn create_index() -> TempIndex {
     let index = TempIndex::new();
@@ -28,7 +28,7 @@ fn create_index() -> TempIndex {
         .update_settings(|s| {
             s.set_primary_key("id".to_owned());
             s.set_searchable_fields(vec!["text".to_owned()]);
-            s.set_criteria(vec![Criterion::Words]);
+            s.set_ranking_rules(vec![RankingRule::Words]);
         })
         .unwrap();
 

milli/src/search/new/tests/proximity.rs

@@ -19,7 +19,7 @@ use std::collections::BTreeMap;
 
 use crate::index::tests::TempIndex;
 use crate::search::new::tests::collect_field_values;
-use crate::{Criterion, Search, SearchResult, TermsMatchingStrategy};
+use crate::{RankingRule, Search, SearchResult, TermsMatchingStrategy};
 
 fn create_simple_index() -> TempIndex {
     let index = TempIndex::new();
@@ -28,7 +28,7 @@ fn create_simple_index() -> TempIndex {
         .update_settings(|s| {
             s.set_primary_key("id".to_owned());
             s.set_searchable_fields(vec!["text".to_owned()]);
-            s.set_criteria(vec![Criterion::Words, Criterion::Proximity]);
+            s.set_ranking_rules(vec![RankingRule::Words, RankingRule::Proximity]);
         })
         .unwrap();
 
@@ -94,7 +94,7 @@ fn create_edge_cases_index() -> TempIndex {
         .update_settings(|s| {
             s.set_primary_key("id".to_owned());
             s.set_searchable_fields(vec!["text".to_owned()]);
-            s.set_criteria(vec![Criterion::Words, Criterion::Proximity]);
+            s.set_ranking_rules(vec![RankingRule::Words, RankingRule::Proximity]);
         })
         .unwrap();
 

milli/src/search/new/tests/proximity_typo.rs

@@ -8,7 +8,7 @@ implemented.
 
 use crate::index::tests::TempIndex;
 use crate::search::new::tests::collect_field_values;
-use crate::{Criterion, Search, SearchResult, TermsMatchingStrategy};
+use crate::{RankingRule, Search, SearchResult, TermsMatchingStrategy};
 
 fn create_index() -> TempIndex {
     let index = TempIndex::new();
@@ -17,7 +17,11 @@ fn create_index() -> TempIndex {
         .update_settings(|s| {
             s.set_primary_key("id".to_owned());
             s.set_searchable_fields(vec!["text".to_owned()]);
-            s.set_criteria(vec![Criterion::Words, Criterion::Proximity, Criterion::Typo]);
+            s.set_ranking_rules(vec![
+                RankingRule::Words,
+                RankingRule::Proximity,
+                RankingRule::Typo,
+            ]);
         })
         .unwrap();
 

milli/src/search/new/tests/sort.rs

@@ -17,7 +17,7 @@ use maplit::hashset;
 use crate::index::tests::TempIndex;
 use crate::search::new::tests::collect_field_values;
 use crate::{
-    score_details, AscDesc, Criterion, Member, Search, SearchResult, TermsMatchingStrategy,
+    score_details, AscDesc, Member, RankingRule, Search, SearchResult, TermsMatchingStrategy,
 };
 
 fn create_index() -> TempIndex {
@@ -28,7 +28,7 @@ fn create_index() -> TempIndex {
             s.set_primary_key("id".to_owned());
             s.set_searchable_fields(vec!["text".to_owned()]);
             s.set_sortable_fields(hashset! { S("rank"), S("vague"), S("letter") });
-            s.set_criteria(vec![Criterion::Sort]);
+            s.set_ranking_rules(vec![RankingRule::Sort]);
         })
         .unwrap();
 
@@ -331,7 +331,7 @@ fn test_redacted() {
         .update_settings(|s| {
             s.set_displayed_fields(vec!["text".to_owned(), "vague".to_owned()]);
             s.set_sortable_fields(hashset! { S("rank"), S("vague"), S("letter") });
-            s.set_criteria(vec![Criterion::Sort]);
+            s.set_ranking_rules(vec![RankingRule::Sort]);
         })
         .unwrap();
 

milli/src/search/new/tests/typo.rs

@@ -22,7 +22,7 @@ use std::collections::BTreeMap;
 
 use crate::index::tests::TempIndex;
 use crate::search::new::tests::collect_field_values;
-use crate::{Criterion, Search, SearchResult, TermsMatchingStrategy};
+use crate::{RankingRule, Search, SearchResult, TermsMatchingStrategy};
 
 fn create_index() -> TempIndex {
     let index = TempIndex::new();
@@ -31,7 +31,7 @@ fn create_index() -> TempIndex {
         .update_settings(|s| {
             s.set_primary_key("id".to_owned());
             s.set_searchable_fields(vec!["text".to_owned()]);
-            s.set_criteria(vec![Criterion::Words]);
+            s.set_ranking_rules(vec![RankingRule::Words]);
         })
         .unwrap();
 
@@ -457,7 +457,7 @@ fn test_typo_ranking_rule_not_preceded_by_words_ranking_rule() {
     let index = create_index();
     index
         .update_settings(|s| {
-            s.set_criteria(vec![Criterion::Typo]);
+            s.set_ranking_rules(vec![RankingRule::Typo]);
         })
         .unwrap();
 
@@ -495,7 +495,7 @@ fn test_typo_ranking_rule_not_preceded_by_words_ranking_rule() {
 
     index
         .update_settings(|s| {
-            s.set_criteria(vec![Criterion::Words, Criterion::Typo]);
+            s.set_ranking_rules(vec![RankingRule::Words, RankingRule::Typo]);
         })
         .unwrap();
 
@@ -540,7 +540,7 @@ fn test_typo_bucketing() {
     drop(txn);
     index
         .update_settings(|s| {
-            s.set_criteria(vec![Criterion::Typo]);
+            s.set_ranking_rules(vec![RankingRule::Typo]);
         })
         .unwrap();
     let txn = index.read_txn().unwrap();
@@ -589,7 +589,7 @@ fn test_typo_synonyms() {
     let index = create_index();
     index
         .update_settings(|s| {
-            s.set_criteria(vec![Criterion::Typo]);
+            s.set_ranking_rules(vec![RankingRule::Typo]);
 
             let mut synonyms = BTreeMap::new();
             synonyms.insert("lackadaisical".to_owned(), vec!["lazy".to_owned()]);

milli/src/search/new/tests/typo_proximity.rs

@@ -17,7 +17,7 @@ because the typo ranking rule before it only used the derivation `beautiful`.
 
 use crate::index::tests::TempIndex;
 use crate::search::new::tests::collect_field_values;
-use crate::{Criterion, Search, SearchResult, TermsMatchingStrategy};
+use crate::{RankingRule, Search, SearchResult, TermsMatchingStrategy};
 
 fn create_index() -> TempIndex {
     let index = TempIndex::new();
@@ -26,7 +26,11 @@ fn create_index() -> TempIndex {
         .update_settings(|s| {
             s.set_primary_key("id".to_owned());
             s.set_searchable_fields(vec!["text".to_owned()]);
-            s.set_criteria(vec![Criterion::Words, Criterion::Typo, Criterion::Proximity]);
+            s.set_ranking_rules(vec![
+                RankingRule::Words,
+                RankingRule::Typo,
+                RankingRule::Proximity,
+            ]);
         })
         .unwrap();
 

milli/src/search/new/tests/words_tms.rs

@@ -14,7 +14,7 @@ account by the proximity ranking rule.
 
 use crate::index::tests::TempIndex;
 use crate::search::new::tests::collect_field_values;
-use crate::{Criterion, Search, SearchResult, TermsMatchingStrategy};
+use crate::{RankingRule, Search, SearchResult, TermsMatchingStrategy};
 
 fn create_index() -> TempIndex {
     let index = TempIndex::new();
@@ -23,7 +23,7 @@ fn create_index() -> TempIndex {
         .update_settings(|s| {
             s.set_primary_key("id".to_owned());
             s.set_searchable_fields(vec!["text".to_owned()]);
-            s.set_criteria(vec![Criterion::Words]);
+            s.set_ranking_rules(vec![RankingRule::Words]);
         })
         .unwrap();
 
@@ -265,7 +265,7 @@ fn test_words_proximity_tms_last_simple() {
     let index = create_index();
     index
         .update_settings(|s| {
-            s.set_criteria(vec![Criterion::Words, Criterion::Proximity]);
+            s.set_ranking_rules(vec![RankingRule::Words, RankingRule::Proximity]);
         })
         .unwrap();
 
@@ -346,7 +346,7 @@ fn test_words_proximity_tms_last_phrase() {
     let index = create_index();
     index
         .update_settings(|s| {
-            s.set_criteria(vec![Criterion::Words, Criterion::Proximity]);
+            s.set_ranking_rules(vec![RankingRule::Words, RankingRule::Proximity]);
         })
         .unwrap();
 
@@ -416,7 +416,7 @@ fn test_words_tms_all() {
     let index = create_index();
     index
         .update_settings(|s| {
-            s.set_criteria(vec![Criterion::Words, Criterion::Proximity]);
+            s.set_ranking_rules(vec![RankingRule::Words, RankingRule::Proximity]);
         })
         .unwrap();
 

milli/src/update/settings.rs

@@ -9,9 +9,9 @@ use time::OffsetDateTime;
 
 use super::index_documents::{IndexDocumentsConfig, Transform};
 use super::IndexerConfig;
-use crate::criterion::Criterion;
 use crate::error::UserError;
 use crate::index::{DEFAULT_MIN_WORD_LEN_ONE_TYPO, DEFAULT_MIN_WORD_LEN_TWO_TYPOS};
+use crate::ranking_rule::RankingRule;
 use crate::update::index_documents::IndexDocumentsMethod;
 use crate::update::{IndexDocuments, UpdateIndexingStep};
 use crate::{FieldsIdsMap, Index, OrderBy, Result};
@@ -110,7 +110,7 @@ pub struct Settings<'a, 't, 'u, 'i> {
     displayed_fields: Setting<Vec<String>>,
     filterable_fields: Setting<HashSet<String>>,
     sortable_fields: Setting<HashSet<String>>,
-    criteria: Setting<Vec<Criterion>>,
+    ranking_rules: Setting<Vec<RankingRule>>,
     stop_words: Setting<BTreeSet<String>>,
     non_separator_tokens: Setting<BTreeSet<String>>,
     separator_tokens: Setting<BTreeSet<String>>,
@@ -142,7 +142,7 @@ impl<'a, 't, 'u, 'i> Settings<'a, 't, 'u, 'i> {
             displayed_fields: Setting::NotSet,
             filterable_fields: Setting::NotSet,
             sortable_fields: Setting::NotSet,
-            criteria: Setting::NotSet,
+            ranking_rules: Setting::NotSet,
             stop_words: Setting::NotSet,
             non_separator_tokens: Setting::NotSet,
             separator_tokens: Setting::NotSet,
@@ -194,12 +194,12 @@ impl<'a, 't, 'u, 'i> Settings<'a, 't, 'u, 'i> {
         self.sortable_fields = Setting::Reset;
     }
 
-    pub fn reset_criteria(&mut self) {
-        self.criteria = Setting::Reset;
+    pub fn reset_ranking_rules(&mut self) {
+        self.ranking_rules = Setting::Reset;
     }
 
-    pub fn set_criteria(&mut self, criteria: Vec<Criterion>) {
-        self.criteria = Setting::Set(criteria);
+    pub fn set_ranking_rules(&mut self, ranking_rules: Vec<RankingRule>) {
+        self.ranking_rules = Setting::Set(ranking_rules);
     }
 
     pub fn reset_stop_words(&mut self) {
@@ -696,7 +696,7 @@ impl<'a, 't, 'u, 'i> Settings<'a, 't, 'u, 'i> {
     }
 
     fn update_criteria(&mut self) -> Result<()> {
-        match &self.criteria {
+        match &self.ranking_rules {
             Setting::Set(criteria) => {
                 self.index.put_criteria(self.wtxn, criteria)?;
             }
@@ -924,7 +924,7 @@ mod tests {
     use crate::error::Error;
     use crate::index::tests::TempIndex;
     use crate::update::{ClearDocuments, DeleteDocuments};
-    use crate::{Criterion, Filter, SearchResult};
+    use crate::{Filter, RankingRule, SearchResult};
 
     #[test]
     fn set_and_reset_searchable_fields() {
@@ -1167,7 +1167,7 @@ mod tests {
         index
             .update_settings(|settings| {
                 settings.set_displayed_fields(vec![S("name")]);
-                settings.set_criteria(vec![Criterion::Asc("age".to_owned())]);
+                settings.set_ranking_rules(vec![RankingRule::Asc("age".to_owned())]);
             })
             .unwrap();
 
@@ -1473,7 +1473,7 @@ mod tests {
             .update_settings(|settings| {
                 settings.set_displayed_fields(vec!["hello".to_string()]);
                 settings.set_filterable_fields(hashset! { S("age"), S("toto") });
-                settings.set_criteria(vec![Criterion::Asc(S("toto"))]);
+                settings.set_ranking_rules(vec![RankingRule::Asc(S("toto"))]);
             })
             .unwrap();
 
@@ -1482,7 +1482,7 @@ mod tests {
         assert_eq!(&["hello"][..], index.displayed_fields(&rtxn).unwrap().unwrap());
         // since no documents have been pushed the primary key is still unset
         assert!(index.primary_key(&rtxn).unwrap().is_none());
-        assert_eq!(vec![Criterion::Asc("toto".to_string())], index.criteria(&rtxn).unwrap());
+        assert_eq!(vec![RankingRule::Asc("toto".to_string())], index.criteria(&rtxn).unwrap());
         drop(rtxn);
 
         // We set toto and age as searchable to force reordering of the fields
@@ -1495,7 +1495,7 @@ mod tests {
         let rtxn = index.read_txn().unwrap();
         assert_eq!(&["hello"][..], index.displayed_fields(&rtxn).unwrap().unwrap());
         assert!(index.primary_key(&rtxn).unwrap().is_none());
-        assert_eq!(vec![Criterion::Asc("toto".to_string())], index.criteria(&rtxn).unwrap());
+        assert_eq!(vec![RankingRule::Asc("toto".to_string())], index.criteria(&rtxn).unwrap());
     }
 
     #[test]
@@ -1507,7 +1507,7 @@ mod tests {
             .update_settings(|settings| {
                 settings.set_displayed_fields(vec!["hello".to_string()]);
                 // It is only Asc(toto), there is a facet database but it is denied to filter with toto.
-                settings.set_criteria(vec![Criterion::Asc(S("toto"))]);
+                settings.set_ranking_rules(vec![RankingRule::Asc(S("toto"))]);
             })
             .unwrap();
 
@@ -1715,7 +1715,7 @@ mod tests {
                     displayed_fields,
                     filterable_fields,
                     sortable_fields,
-                    criteria,
+                    ranking_rules: criteria,
                     stop_words,
                     non_separator_tokens,
                     separator_tokens,

milli/tests/search/distinct.rs

@@ -2,8 +2,8 @@ use std::collections::HashSet;
 
 use big_s::S;
 use milli::update::Settings;
-use milli::{Criterion, Search, SearchResult, TermsMatchingStrategy};
-use Criterion::*;
+use milli::{RankingRule, Search, SearchResult, TermsMatchingStrategy};
+use RankingRule::*;
 
 use crate::search::{self, EXTERNAL_DOCUMENTS_IDS};
 

milli/tests/search/filters.rs

@@ -1,6 +1,6 @@
 use either::{Either, Left, Right};
-use milli::{Criterion, Filter, Search, SearchResult, TermsMatchingStrategy};
-use Criterion::*;
+use milli::{Filter, RankingRule, Search, SearchResult, TermsMatchingStrategy};
+use RankingRule::*;
 
 use crate::search::{self, EXTERNAL_DOCUMENTS_IDS};
 

milli/tests/search/mod.rs

@@ -8,7 +8,7 @@ use heed::EnvOpenOptions;
 use maplit::{btreemap, hashset};
 use milli::documents::{DocumentsBatchBuilder, DocumentsBatchReader};
 use milli::update::{IndexDocuments, IndexDocumentsConfig, IndexerConfig, Settings};
-use milli::{AscDesc, Criterion, DocumentId, Index, Member, Object, TermsMatchingStrategy};
+use milli::{AscDesc, DocumentId, Index, Member, Object, RankingRule, TermsMatchingStrategy};
 use serde::{Deserialize, Deserializer};
 use slice_group_by::GroupBy;
 
@@ -27,7 +27,7 @@ pub const EXTERNAL_DOCUMENTS_IDS: &[&str; 17] =
 
 pub const CONTENT: &str = include_str!("../assets/test_set.ndjson");
 
-pub fn setup_search_index_with_criteria(criteria: &[Criterion]) -> Index {
+pub fn setup_search_index_with_criteria(criteria: &[RankingRule]) -> Index {
     let path = tempfile::tempdir().unwrap();
     let mut options = EnvOpenOptions::new();
     options.map_size(10 * 1024 * 1024); // 10 MB
@@ -38,7 +38,7 @@ pub fn setup_search_index_with_criteria(criteria: &[Criterion]) -> Index {
 
     let mut builder = Settings::new(&mut wtxn, &index, &config);
 
-    builder.set_criteria(criteria.to_vec());
+    builder.set_ranking_rules(criteria.to_vec());
     builder.set_filterable_fields(hashset! {
         S("tag"),
         S("asc_desc_rank"),
@@ -95,7 +95,7 @@ pub fn internal_to_external_ids(index: &Index, internal_ids: &[DocumentId]) -> V
 }
 
 pub fn expected_order(
-    criteria: &[Criterion],
+    criteria: &[RankingRule],
     optional_words: TermsMatchingStrategy,
     sort_by: &[AscDesc],
 ) -> Vec<TestDocument> {
@@ -107,47 +107,56 @@ pub fn expected_order(
         let mut new_groups = Vec::new();
         for group in groups.iter_mut() {
             match criterion {
-                Criterion::Attribute => {
+                RankingRule::Attribute => {
                     group.sort_by_key(|d| d.attribute_rank);
                     new_groups
                         .extend(group.linear_group_by_key(|d| d.attribute_rank).map(Vec::from));
                 }
-                Criterion::Exactness => {
+                RankingRule::Exactness => {
                     group.sort_by_key(|d| d.exact_rank);
                     new_groups.extend(group.linear_group_by_key(|d| d.exact_rank).map(Vec::from));
                 }
-                Criterion::Proximity => {
+                RankingRule::Proximity => {
                     group.sort_by_key(|d| d.proximity_rank);
                     new_groups
                         .extend(group.linear_group_by_key(|d| d.proximity_rank).map(Vec::from));
                 }
-                Criterion::Sort if sort_by == [AscDesc::Asc(Member::Field(S("tag")))] => {
+                RankingRule::Sort if sort_by == [AscDesc::Asc(Member::Field(S("tag")))] => {
                     group.sort_by_key(|d| d.sort_by_rank);
                     new_groups.extend(group.linear_group_by_key(|d| d.sort_by_rank).map(Vec::from));
                 }
-                Criterion::Sort if sort_by == [AscDesc::Desc(Member::Field(S("tag")))] => {
+                RankingRule::Sort if sort_by == [AscDesc::Desc(Member::Field(S("tag")))] => {
                     group.sort_by_key(|d| Reverse(d.sort_by_rank));
                     new_groups.extend(group.linear_group_by_key(|d| d.sort_by_rank).map(Vec::from));
                 }
-                Criterion::Typo => {
+                RankingRule::Typo => {
                     group.sort_by_key(|d| d.typo_rank);
                     new_groups.extend(group.linear_group_by_key(|d| d.typo_rank).map(Vec::from));
                 }
-                Criterion::Words => {
+                RankingRule::Words => {
                     group.sort_by_key(|d| d.word_rank);
                     new_groups.extend(group.linear_group_by_key(|d| d.word_rank).map(Vec::from));
                 }
-                Criterion::Asc(field_name) if field_name == "asc_desc_rank" => {
+                RankingRule::Asc(field_name) if field_name == "asc_desc_rank" => {
                     group.sort_by_key(|d| d.asc_desc_rank);
                     new_groups
                         .extend(group.linear_group_by_key(|d| d.asc_desc_rank).map(Vec::from));
                 }
-                Criterion::Desc(field_name) if field_name == "asc_desc_rank" => {
+                RankingRule::Desc(field_name) if field_name == "asc_desc_rank" => {
                     group.sort_by_key(|d| Reverse(d.asc_desc_rank));
                     new_groups
                         .extend(group.linear_group_by_key(|d| d.asc_desc_rank).map(Vec::from));
                 }
-                Criterion::Asc(_) | Criterion::Desc(_) | Criterion::Sort => {
+                RankingRule::Boost(filter) => {
+                    // move the matching documents first, then the ones that don't match
+                    group.sort_by_key(|d| if execute_filter(filter, d).is_some() { 0 } else { 1 });
+                    new_groups.extend(
+                        group
+                            .linear_group_by_key(|d| execute_filter(filter, d).is_some())
+                            .map(Vec::from),
+                    );
+                }
+                RankingRule::Asc(_) | RankingRule::Desc(_) | RankingRule::Sort => {
                     new_groups.push(group.clone())
                 }
             }

milli/tests/search/phrase_search.rs

@@ -1,7 +1,7 @@
 use milli::update::{IndexerConfig, Settings};
-use milli::{Criterion, Index, Search, TermsMatchingStrategy};
+use milli::{Index, RankingRule, Search, TermsMatchingStrategy};
 
-use crate::search::Criterion::{Attribute, Exactness, Proximity};
+use crate::search::RankingRule::{Attribute, Exactness, Proximity};
 
 fn set_stop_words(index: &Index, stop_words: &[&str]) {
     let mut wtxn = index.write_txn().unwrap();
@@ -14,7 +14,7 @@ fn set_stop_words(index: &Index, stop_words: &[&str]) {
     wtxn.commit().unwrap();
 }
 
-fn test_phrase_search_with_stop_words_given_criteria(criteria: &[Criterion]) {
+fn test_phrase_search_with_stop_words_given_criteria(criteria: &[RankingRule]) {
     let index = super::setup_search_index_with_criteria(criteria);
 
     // Add stop_words

milli/tests/search/query_criteria.rs

@@ -7,9 +7,9 @@ use itertools::Itertools;
 use maplit::hashset;
 use milli::documents::{DocumentsBatchBuilder, DocumentsBatchReader};
 use milli::update::{IndexDocuments, IndexDocumentsConfig, IndexerConfig, Settings};
-use milli::{AscDesc, Criterion, Index, Member, Search, SearchResult, TermsMatchingStrategy};
+use milli::{AscDesc, Index, Member, RankingRule, Search, SearchResult, TermsMatchingStrategy};
 use rand::Rng;
-use Criterion::*;
+use RankingRule::*;
 
 use crate::search::{self, EXTERNAL_DOCUMENTS_IDS};
 
@@ -88,7 +88,7 @@ test_criterion!(
 
 #[test]
 fn criteria_mixup() {
-    use Criterion::*;
+    use RankingRule::*;
     let index = search::setup_search_index_with_criteria(&[
         Words,
         Attribute,
@@ -233,7 +233,7 @@ fn criteria_mixup() {
         //update criteria
         let mut wtxn = index.write_txn().unwrap();
         let mut builder = Settings::new(&mut wtxn, &index, &config);
-        builder.set_criteria(criteria.clone());
+        builder.set_ranking_rules(criteria.clone());
         builder.execute(|_| (), || false).unwrap();
         wtxn.commit().unwrap();
 
@@ -324,7 +324,7 @@ fn criteria_ascdesc() {
 
         let mut wtxn = index.write_txn().unwrap();
         let mut builder = Settings::new(&mut wtxn, &index, &config);
-        builder.set_criteria(vec![criterion.clone()]);
+        builder.set_ranking_rules(vec![criterion.clone()]);
         builder.execute(|_| (), || false).unwrap();
         wtxn.commit().unwrap();
 

milli/tests/search/sort.rs

@@ -1,5 +1,5 @@
 use big_s::S;
-use milli::Criterion::{Attribute, Exactness, Proximity, Typo, Words};
+use milli::RankingRule::{Attribute, Exactness, Proximity, Typo, Words};
 use milli::{AscDesc, Error, Member, Search, TermsMatchingStrategy, UserError};
 
 use crate::search::{self, EXTERNAL_DOCUMENTS_IDS};

milli/tests/search/typo_tolerance.rs

@@ -2,10 +2,10 @@ use std::collections::BTreeSet;
 
 use heed::EnvOpenOptions;
 use milli::update::{IndexDocuments, IndexDocumentsConfig, IndexerConfig, Settings};
-use milli::{Criterion, Index, Search, TermsMatchingStrategy};
+use milli::{Index, RankingRule, Search, TermsMatchingStrategy};
 use serde_json::json;
 use tempfile::tempdir;
-use Criterion::*;
+use RankingRule::*;
 
 #[test]
 fn test_typo_tolerance_one_typo() {