feat: add num_deleted_rows to delete result (#3077)

docs/src/js/interfaces/DeleteResult.md

@@ -8,6 +8,14 @@
 
 ## Properties
 
+### numDeletedRows
+
+```ts
+numDeletedRows: number;
+```
+
+***
+
 ### version
 
 ```ts

nodejs/src/table.rs

@@ -753,12 +753,14 @@ impl From<lancedb::table::AddResult> for AddResult {
 
 #[napi(object)]
 pub struct DeleteResult {
+    pub num_deleted_rows: i64,
     pub version: i64,
 }
 
 impl From<lancedb::table::DeleteResult> for DeleteResult {
     fn from(value: lancedb::table::DeleteResult) -> Self {
         Self {
+            num_deleted_rows: value.num_deleted_rows as i64,
             version: value.version as i64,
         }
     }

python/python/lancedb/table.py

@@ -1331,7 +1331,7 @@ class Table(ABC):
         1  2  [3.0, 4.0]
         2  3  [5.0, 6.0]
         >>> table.delete("x = 2")
-        DeleteResult(version=2)
+        DeleteResult(num_deleted_rows=1, version=2)
         >>> table.to_pandas()
            x      vector
         0  1  [1.0, 2.0]
@@ -1345,7 +1345,7 @@ class Table(ABC):
         >>> to_remove
         '1, 5'
         >>> table.delete(f"x IN ({to_remove})")
-        DeleteResult(version=3)
+        DeleteResult(num_deleted_rows=1, version=3)
         >>> table.to_pandas()
            x      vector
         0  3  [5.0, 6.0]
@@ -4215,7 +4215,7 @@ class AsyncTable:
         1  2  [3.0, 4.0]
         2  3  [5.0, 6.0]
         >>> table.delete("x = 2")
-        DeleteResult(version=2)
+        DeleteResult(num_deleted_rows=1, version=2)
         >>> table.to_pandas()
            x      vector
         0  1  [1.0, 2.0]
@@ -4229,7 +4229,7 @@ class AsyncTable:
         >>> to_remove
         '1, 5'
         >>> table.delete(f"x IN ({to_remove})")
-        DeleteResult(version=3)
+        DeleteResult(num_deleted_rows=1, version=3)
         >>> table.to_pandas()
            x      vector
         0  3  [5.0, 6.0]

python/src/table.rs

@@ -112,19 +112,24 @@ impl From<lancedb::table::AddResult> for AddResult {
 #[pyclass(get_all)]
 #[derive(Clone, Debug)]
 pub struct DeleteResult {
+    pub num_deleted_rows: u64,
     pub version: u64,
 }
 
 #[pymethods]
 impl DeleteResult {
     pub fn __repr__(&self) -> String {
-        format!("DeleteResult(version={})", self.version)
+        format!(
+            "DeleteResult(num_deleted_rows={}, version={})",
+            self.num_deleted_rows, self.version
+        )
     }
 }
 
 impl From<lancedb::table::DeleteResult> for DeleteResult {
     fn from(result: lancedb::table::DeleteResult) -> Self {
         Self {
+            num_deleted_rows: result.num_deleted_rows,
             version: result.version,
         }
     }

rust/lancedb/src/remote/table.rs

@@ -1227,7 +1227,10 @@ impl<S: HttpSend> BaseTable for RemoteTable<S> {
         let body = response.text().await.err_to_http(request_id.clone())?;
         if body.trim().is_empty() {
             // Backward compatible with old servers
-            return Ok(DeleteResult { version: 0 });
+            return Ok(DeleteResult {
+                num_deleted_rows: 0,
+                version: 0,
+            });
         }
         let delete_response: DeleteResult =
             serde_json::from_str(&body).map_err(|e| Error::Http {

rust/lancedb/src/table/delete.rs

@@ -7,6 +7,9 @@ use crate::Result;
 
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Default)]
 pub struct DeleteResult {
+    /// The number of rows that were deleted.
+    #[serde(default)]
+    pub num_deleted_rows: u64,
     // The commit version associated with the operation.
     // A version of `0` indicates compatibility with legacy servers that do not return
     /// a commit version.
@@ -20,10 +23,14 @@ pub struct DeleteResult {
 pub(crate) async fn execute_delete(table: &NativeTable, predicate: &str) -> Result<DeleteResult> {
     table.dataset.ensure_mutable()?;
     let mut dataset = (*table.dataset.get().await?).clone();
-    dataset.delete(predicate).await?;
+    let delete_result = dataset.delete(predicate).await?;
+    let num_deleted_rows = delete_result.num_deleted_rows;
     let version = dataset.version().version;
     table.dataset.update(dataset);
-    Ok(DeleteResult { version })
+    Ok(DeleteResult {
+        num_deleted_rows,
+        version,
+    })
 }
 
 #[cfg(test)]
@@ -108,6 +115,32 @@ mod tests {
         assert_eq!(current_schema, original_schema);
     }
 
+    #[tokio::test]
+    async fn test_delete_returns_num_deleted_rows() {
+        let conn = connect("memory://").execute().await.unwrap();
+        let batch = record_batch!(("id", Int32, [1, 2, 3, 4, 5])).unwrap();
+        let table = conn
+            .create_table("test_num_deleted", batch)
+            .execute()
+            .await
+            .unwrap();
+
+        // Delete 2 rows (id > 3 means id=4 and id=5)
+        let result = table.delete("id > 3").await.unwrap();
+        assert_eq!(result.num_deleted_rows, 2);
+        assert_eq!(table.count_rows(None).await.unwrap(), 3);
+
+        // Delete 0 rows (no rows match)
+        let result = table.delete("id > 100").await.unwrap();
+        assert_eq!(result.num_deleted_rows, 0);
+        assert_eq!(table.count_rows(None).await.unwrap(), 3);
+
+        // Delete remaining rows
+        let result = table.delete("true").await.unwrap();
+        assert_eq!(result.num_deleted_rows, 3);
+        assert_eq!(table.count_rows(None).await.unwrap(), 0);
+    }
+
     #[tokio::test]
     async fn test_delete_false_increments_version() {
         let conn = connect("memory://").execute().await.unwrap();