Use the RoaringBitmapLenCodec to retrieve the count of documents

milli/src/index.rs

@@ -118,6 +118,12 @@ impl Index {
         Ok(self.main.get::<_, Str, RoaringBitmapCodec>(rtxn, DOCUMENTS_IDS_KEY)?.unwrap_or_default())
     }
 
+    /// Returns the number of documents indexed in the database.
+    pub fn number_of_documents(&self, rtxn: &RoTxn) -> anyhow::Result<u64> {
+        let count = self.main.get::<_, Str, RoaringBitmapLenCodec>(rtxn, DOCUMENTS_IDS_KEY)?;
+        Ok(count.unwrap_or_default())
+    }
+
     /* primary key */
 
     /// Writes the documents primary key, this is the field name that is used to store the id.
@@ -380,11 +386,6 @@ impl Index {
         Ok(documents)
     }
 
-    /// Returns the number of documents indexed in the database.
-    pub fn number_of_documents(&self, rtxn: &RoTxn) -> anyhow::Result<usize> {
-        Ok(self.documents_ids(rtxn).map(|docids| docids.len() as usize)?)
-    }
-
     pub fn facets_distribution<'a>(&'a self, rtxn: &'a RoTxn) -> FacetDistribution<'a> {
         FacetDistribution::new(rtxn, self)
     }

milli/src/update/clear_documents.rs

@@ -17,7 +17,7 @@ impl<'t, 'u, 'i> ClearDocuments<'t, 'u, 'i> {
         ClearDocuments { wtxn, index, _update_id: update_id }
     }
 
-    pub fn execute(self) -> anyhow::Result<usize> {
+    pub fn execute(self) -> anyhow::Result<u64> {
         let Index {
             env: _env,
             main: _main,

milli/src/update/delete_documents.rs

@@ -51,7 +51,7 @@ impl<'t, 'u, 'i> DeleteDocuments<'t, 'u, 'i> {
         Some(docid)
     }
 
-    pub fn execute(self) -> anyhow::Result<usize> {
+    pub fn execute(self) -> anyhow::Result<u64> {
         // We retrieve the current documents ids that are in the database.
         let mut documents_ids = self.index.documents_ids(self.wtxn)?;
 
@@ -308,7 +308,7 @@ impl<'t, 'u, 'i> DeleteDocuments<'t, 'u, 'i> {
 
         drop(iter);
 
-        Ok(self.documents_ids.len() as usize)
+        Ok(self.documents_ids.len())
     }
 }