diff --git a/milli/src/documents/mod.rs b/milli/src/documents/mod.rs
index 4429f083d..a874ac17e 100644
--- a/milli/src/documents/mod.rs
+++ b/milli/src/documents/mod.rs
@@ -12,9 +12,7 @@ use bimap::BiHashMap;
 pub use builder::DocumentsBatchBuilder;
 pub use enriched::{EnrichedDocument, EnrichedDocumentsBatchCursor, EnrichedDocumentsBatchReader};
 use obkv::KvReader;
-pub use primary_key::{
-    DocumentIdExtractionError, FieldDistribution, PrimaryKey, DEFAULT_PRIMARY_KEY,
-};
+pub use primary_key::{DocumentIdExtractionError, FieldIdMapper, PrimaryKey, DEFAULT_PRIMARY_KEY};
 pub use reader::{DocumentsBatchCursor, DocumentsBatchCursorError, DocumentsBatchReader};
 use serde::{Deserialize, Serialize};
 
@@ -91,7 +89,7 @@ impl DocumentsBatchIndex {
     }
 }
 
-impl FieldDistribution for DocumentsBatchIndex {
+impl FieldIdMapper for DocumentsBatchIndex {
     fn id(&self, name: &str) -> Option<FieldId> {
         self.id(name)
     }
diff --git a/milli/src/documents/primary_key.rs b/milli/src/documents/primary_key.rs
index dd97f2608..16a95c21f 100644
--- a/milli/src/documents/primary_key.rs
+++ b/milli/src/documents/primary_key.rs
@@ -11,7 +11,11 @@ const PRIMARY_KEY_SPLIT_SYMBOL: char = '.';
 /// The default primary that is used when not specified.
 pub const DEFAULT_PRIMARY_KEY: &str = "id";
 
-pub trait FieldDistribution {
+/// Trait for objects that can map the name of a field to its [`FieldId`].
+pub trait FieldIdMapper {
+    /// Attempts to map the passed name to its [`FieldId`].
+    ///
+    /// `None` if the field with this name was not found.
     fn id(&self, name: &str) -> Option<FieldId>;
 }
 
@@ -30,7 +34,7 @@ pub enum DocumentIdExtractionError {
 }
 
 impl<'a> PrimaryKey<'a> {
-    pub fn new(path: &'a str, fields: &impl FieldDistribution) -> Option<Self> {
+    pub fn new(path: &'a str, fields: &impl FieldIdMapper) -> Option<Self> {
         Some(if path.contains(PRIMARY_KEY_SPLIT_SYMBOL) {
             Self::Nested { name: path }
         } else {
@@ -49,7 +53,7 @@ impl<'a> PrimaryKey<'a> {
     pub fn document_id(
         &self,
         document: &obkv::KvReader<FieldId>,
-        fields: &impl FieldDistribution,
+        fields: &impl FieldIdMapper,
     ) -> Result<StdResult<String, DocumentIdExtractionError>> {
         match self {
             PrimaryKey::Flat { name: _, field_id } => match document.get(*field_id) {
diff --git a/milli/src/fields_ids_map.rs b/milli/src/fields_ids_map.rs
index 85320c168..9c1c87f82 100644
--- a/milli/src/fields_ids_map.rs
+++ b/milli/src/fields_ids_map.rs
@@ -81,7 +81,7 @@ impl Default for FieldsIdsMap {
     }
 }
 
-impl crate::documents::FieldDistribution for FieldsIdsMap {
+impl crate::documents::FieldIdMapper for FieldsIdsMap {
     fn id(&self, name: &str) -> Option<FieldId> {
         self.id(name)
     }