Remove soft deleted ids from ExternalDocumentIds during document import

If the document import replaces a document using hard deletion

milli/src/update/delete_documents.rs

@@ -34,6 +34,12 @@ pub struct DocumentDeletionResult {
     pub deleted_documents: u64,
     pub remaining_documents: u64,
 }
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct DetailedDocumentDeletionResult {
+    pub deleted_documents: u64,
+    pub remaining_documents: u64,
+    pub used_soft_deletion: bool,
+}
 
 impl<'t, 'u, 'i> DeleteDocuments<'t, 'u, 'i> {
     pub fn new(
@@ -68,8 +74,16 @@ impl<'t, 'u, 'i> DeleteDocuments<'t, 'u, 'i> {
         self.delete_document(docid);
         Some(docid)
     }
-
-    pub fn execute(mut self) -> Result<DocumentDeletionResult> {
+    pub fn execute(self) -> Result<DocumentDeletionResult> {
+        let DetailedDocumentDeletionResult {
+            deleted_documents,
+            remaining_documents,
+            used_soft_deletion: _,
+        } = self.execute_inner()?;
+
+        Ok(DocumentDeletionResult { deleted_documents, remaining_documents })
+    }
+    pub(crate) fn execute_inner(mut self) -> Result<DetailedDocumentDeletionResult> {
         self.index.set_updated_at(self.wtxn, &OffsetDateTime::now_utc())?;
 
         // We retrieve the current documents ids that are in the database.
@@ -83,7 +97,11 @@ impl<'t, 'u, 'i> DeleteDocuments<'t, 'u, 'i> {
             if !soft_deleted_docids.is_empty() {
                 ClearDocuments::new(self.wtxn, self.index).execute()?;
             }
-            return Ok(DocumentDeletionResult { deleted_documents: 0, remaining_documents: 0 });
+            return Ok(DetailedDocumentDeletionResult {
+                deleted_documents: 0,
+                remaining_documents: 0,
+                used_soft_deletion: false,
+            });
         }
 
         // We remove the documents ids that we want to delete
@@ -95,9 +113,10 @@ impl<'t, 'u, 'i> DeleteDocuments<'t, 'u, 'i> {
         // to delete is exactly the number of documents in the database.
         if current_documents_ids_len == self.to_delete_docids.len() {
             let remaining_documents = ClearDocuments::new(self.wtxn, self.index).execute()?;
-            return Ok(DocumentDeletionResult {
+            return Ok(DetailedDocumentDeletionResult {
                 deleted_documents: current_documents_ids_len,
                 remaining_documents,
+                used_soft_deletion: false,
             });
         }
 
@@ -159,9 +178,10 @@ impl<'t, 'u, 'i> DeleteDocuments<'t, 'u, 'i> {
             && percentage_used_by_soft_deleted_documents < 10
         {
             self.index.put_soft_deleted_documents_ids(self.wtxn, &soft_deleted_docids)?;
-            return Ok(DocumentDeletionResult {
+            return Ok(DetailedDocumentDeletionResult {
                 deleted_documents: self.to_delete_docids.len(),
                 remaining_documents: documents_ids.len(),
+                used_soft_deletion: true,
             });
         }
 
@@ -488,9 +508,10 @@ impl<'t, 'u, 'i> DeleteDocuments<'t, 'u, 'i> {
             &self.to_delete_docids,
         )?;
 
-        Ok(DocumentDeletionResult {
+        Ok(DetailedDocumentDeletionResult {
             deleted_documents: self.to_delete_docids.len(),
             remaining_documents: documents_ids.len(),
+            used_soft_deletion: false,
         })
     }
 }

milli/src/update/index_documents/mod.rs

@@ -210,7 +210,7 @@ where
             primary_key,
             fields_ids_map,
             field_distribution,
-            external_documents_ids,
+            mut external_documents_ids,
             new_documents_ids,
             replaced_documents_ids,
             documents_count,
@@ -335,8 +335,11 @@ where
             deletion_builder.disable_soft_deletion(self.config.disable_soft_deletion);
             debug!("documents to delete {:?}", replaced_documents_ids);
             deletion_builder.delete_documents(&replaced_documents_ids);
-            let deleted_documents_count = deletion_builder.execute()?;
-            debug!("{} documents actually deleted", deleted_documents_count.deleted_documents);
+            let deleted_documents_result = deletion_builder.execute_inner()?;
+            debug!("{} documents actually deleted", deleted_documents_result.deleted_documents);
+            if !deleted_documents_result.used_soft_deletion {
+                external_documents_ids.delete_soft_deleted_documents_ids_from_fsts()?;
+            }
         }
 
         let index_documents_ids = self.index.documents_ids(self.wtxn)?;