From 267577989ba1af96ccf73f3d4ef0c58721f15720 Mon Sep 17 00:00:00 2001
From: Gatefixer <313497061+lancedb-gatefixer[bot]@users.noreply.github.com>
Date: Wed, 5 Aug 2026 23:26:26 +0000
Subject: [PATCH] test(rust): cover large indexed deletes

---
 rust/lancedb/src/table/delete.rs | 45 ++++++++++++++++++++++++++++++--
 1 file changed, 43 insertions(+), 2 deletions(-)

diff --git a/rust/lancedb/src/table/delete.rs b/rust/lancedb/src/table/delete.rs
index 8f11ee019..d57ae9cf7 100644
--- a/rust/lancedb/src/table/delete.rs
+++ b/rust/lancedb/src/table/delete.rs
@@ -62,11 +62,12 @@ pub(crate) async fn execute_delete(
 #[cfg(test)]
 mod tests {
     use crate::connect;
-    use arrow_array::{Int32Array, RecordBatch, record_batch};
+    use arrow_array::{Int32Array, RecordBatch, StringArray, record_batch};
     use arrow_schema::{DataType, Field, Schema};
     use std::sync::Arc;
 
-    use crate::query::ExecutableQuery;
+    use crate::index::Index;
+    use crate::query::{ExecutableQuery, QueryBase};
     use futures::TryStreamExt;
     #[tokio::test]
     async fn test_delete_simple() {
@@ -167,6 +168,46 @@ mod tests {
         assert_eq!(table.count_rows(None).await.unwrap(), 0);
     }
 
+    #[tokio::test]
+    async fn test_delete_large_in_list_with_btree_index() {
+        let conn = connect("memory://").execute().await.unwrap();
+        let schema = Arc::new(Schema::new(vec![Field::new("id", DataType::Utf8, false)]));
+        let ids = StringArray::from_iter_values((0..10_000).map(|id| format!("id_{id}")));
+        let batch = RecordBatch::try_new(schema, vec![Arc::new(ids)]).unwrap();
+        let table = conn
+            .create_table("test_delete_large_in_list", batch)
+            .execute()
+            .await
+            .unwrap();
+
+        table
+            .create_index(&["id"], Index::BTree(Default::default()))
+            .execute()
+            .await
+            .unwrap();
+
+        let values = (0..10_000)
+            .step_by(10)
+            .map(|id| format!("'id_{id}'"))
+            .collect::<Vec<_>>()
+            .join(",");
+        let predicate = format!("id IN ({values})");
+
+        // A large IN-list must stay on the scalar-index path. Lance compiles this
+        // predicate once and reuses it across all BTree pages.
+        let plan = table
+            .query()
+            .only_if(&predicate)
+            .explain_plan(false)
+            .await
+            .unwrap();
+        assert!(plan.contains("ScalarIndexQuery"), "unexpected plan: {plan}");
+
+        let result = table.delete(&predicate).await.unwrap();
+        assert_eq!(result.num_deleted_rows, 1_000);
+        assert_eq!(table.count_rows(None).await.unwrap(), 9_000);
+    }
+
     #[tokio::test]
     async fn test_delete_false_increments_version() {
         let conn = connect("memory://").execute().await.unwrap();