fix: support nested-list FTS indexing (#4059)

## Summary

- validate native FTS fields against the recursively resolved terminal
text leaf
- preserve canonical public paths and list depth for Lance
document-boundary handling
- cover async nested-list index creation and deepest-list `_doc_index`
search coordinates

## Root cause

The FTS resolver recursively found the terminal text field but returned
the outer list field. Native validation therefore rejected
`List(List(Utf8))` before Lance could create a list-element index.

## Validation

- `cargo test --quiet --features remote -p lancedb
test_nested_list_fts_uses_deepest_document_coordinates -- --nocapture`
- `cargo test --quiet --features remote -p lancedb
test_execute_async_validates_fts_input_before_starting_job`
- `cargo test --quiet --features remote -p lancedb
test_public_fts_field_path_prefers_exact_case`
- `cargo check --quiet --features remote --tests --examples`
- `cargo clippy --quiet --features remote --tests --examples`
- `cargo fmt --all -- --check`

Fixes #4058

<!-- lance-gatekeeper-fix:v1 agent=a4e48f49d12b2b6de7f10adb1c5bf5f5
generation=1 -->

Co-authored-by: Gatefixer <313497061+lancedb-gatefixer[bot]@users.noreply.github.com>

.bumpversion.toml

@@ -1,5 +1,5 @@
 [tool.bumpversion]
-current_version = "0.39.0-beta.0"
+current_version = "0.39.0-beta.1"
 parse = """(?x)
     (?P<major>0|[1-9]\\d*)\\.
     (?P<minor>0|[1-9]\\d*)\\.

Cargo.lock

@@ -5403,7 +5403,7 @@ dependencies = [
 
 [[package]]
 name = "lancedb"
-version = "0.39.0-beta.0"
+version = "0.39.0-beta.1"
 dependencies = [
  "ahash",
  "anyhow",
@@ -5491,7 +5491,7 @@ dependencies = [
 
 [[package]]
 name = "lancedb-nodejs"
-version = "0.39.0-beta.0"
+version = "0.39.0-beta.1"
 dependencies = [
  "arrow-array",
  "arrow-buffer",
@@ -5516,7 +5516,7 @@ dependencies = [
 
 [[package]]
 name = "lancedb-python"
-version = "0.39.0-beta.0"
+version = "0.39.0-beta.1"
 dependencies = [
  "arrow",
  "async-trait",

docs/src/java/java.md

@@ -14,7 +14,7 @@ Add the following dependency to your `pom.xml`:
 <dependency>
     <groupId>com.lancedb</groupId>
     <artifactId>lancedb-core</artifactId>
-    <version>0.39.0-beta.0</version>
+    <version>0.39.0-beta.1</version>
 </dependency>
 ```
 

java/lancedb-core/pom.xml

@@ -8,7 +8,7 @@
     <parent>
       <groupId>com.lancedb</groupId>
       <artifactId>lancedb-parent</artifactId>
-      <version>0.39.0-beta.0</version>
+      <version>0.39.0-beta.1</version>
       <relativePath>../pom.xml</relativePath>
     </parent>
 

java/pom.xml

@@ -6,7 +6,7 @@
 
     <groupId>com.lancedb</groupId>
     <artifactId>lancedb-parent</artifactId>
-    <version>0.39.0-beta.0</version>
+    <version>0.39.0-beta.1</version>
     <packaging>pom</packaging>
     <name>${project.artifactId}</name>
     <description>LanceDB Java SDK Parent POM</description>

nodejs/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "lancedb-nodejs"
 edition.workspace = true
-version = "0.39.0-beta.0"
+version = "0.39.0-beta.1"
 publish = false
 license.workspace = true
 description.workspace = true

nodejs/npm/darwin-arm64/package.json

@@ -1,6 +1,6 @@
 {
 	"name": "@lancedb/lancedb-darwin-arm64",
-	"version": "0.39.0-beta.0",
+	"version": "0.39.0-beta.1",
 	"os": ["darwin"],
 	"cpu": ["arm64"],
 	"main": "lancedb.darwin-arm64.node",

nodejs/npm/linux-arm64-gnu/package.json

@@ -1,6 +1,6 @@
 {
 	"name": "@lancedb/lancedb-linux-arm64-gnu",
-	"version": "0.39.0-beta.0",
+	"version": "0.39.0-beta.1",
 	"os": ["linux"],
 	"cpu": ["arm64"],
 	"main": "lancedb.linux-arm64-gnu.node",

nodejs/npm/linux-arm64-musl/package.json

@@ -1,6 +1,6 @@
 {
 	"name": "@lancedb/lancedb-linux-arm64-musl",
-	"version": "0.39.0-beta.0",
+	"version": "0.39.0-beta.1",
 	"os": ["linux"],
 	"cpu": ["arm64"],
 	"main": "lancedb.linux-arm64-musl.node",

nodejs/npm/linux-x64-gnu/package.json

@@ -1,6 +1,6 @@
 {
 	"name": "@lancedb/lancedb-linux-x64-gnu",
-	"version": "0.39.0-beta.0",
+	"version": "0.39.0-beta.1",
 	"os": ["linux"],
 	"cpu": ["x64"],
 	"main": "lancedb.linux-x64-gnu.node",

nodejs/npm/linux-x64-musl/package.json

@@ -1,6 +1,6 @@
 {
 	"name": "@lancedb/lancedb-linux-x64-musl",
-	"version": "0.39.0-beta.0",
+	"version": "0.39.0-beta.1",
 	"os": ["linux"],
 	"cpu": ["x64"],
 	"main": "lancedb.linux-x64-musl.node",

nodejs/npm/win32-arm64-msvc/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@lancedb/lancedb-win32-arm64-msvc",
-  "version": "0.39.0-beta.0",
+  "version": "0.39.0-beta.1",
   "os": [
     "win32"
   ],

nodejs/npm/win32-x64-msvc/package.json

@@ -1,6 +1,6 @@
 {
 	"name": "@lancedb/lancedb-win32-x64-msvc",
-	"version": "0.39.0-beta.0",
+	"version": "0.39.0-beta.1",
 	"os": ["win32"],
 	"cpu": ["x64"],
 	"main": "lancedb.win32-x64-msvc.node",

nodejs/package.json

@@ -11,7 +11,7 @@
     "ann"
   ],
   "private": false,
-  "version": "0.39.0-beta.0",
+  "version": "0.39.0-beta.1",
   "main": "dist/index.js",
   "exports": {
     ".": "./dist/index.js",

python/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "lancedb-python"
-version = "0.39.0-beta.0"
+version = "0.39.0-beta.1"
 publish = false
 edition.workspace = true
 description = "Python bindings for LanceDB"

rust/lancedb/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "lancedb"
-version = "0.39.0-beta.0"
+version = "0.39.0-beta.1"
 edition.workspace = true
 description = "LanceDB: A serverless, low-latency vector database for AI applications"
 license.workspace = true

rust/lancedb/src/table/create_index.rs

@@ -133,7 +133,7 @@ impl NativeTable {
                     ),
                 });
             }
-            (resolved.canonical_path, resolved.field)
+            (resolved.canonical_path, resolved.terminal_field)
         } else {
             Self::resolve_index_field(dataset.schema(), &opts.columns[0])?
         };
@@ -439,7 +439,8 @@ mod tests {
     use arrow_array::record_batch;
     use arrow_array::{
         Array, ArrayRef, BinaryArray, BooleanArray, FixedSizeListArray, Float32Array, Int32Array,
-        LargeBinaryArray, LargeStringArray, RecordBatch, StringArray, StructArray,
+        LargeBinaryArray, LargeStringArray, ListArray, RecordBatch, StringArray, StructArray,
+        UInt32Array,
     };
     use arrow_data::ArrayDataBuilder;
     use arrow_schema::{DataType, Field, Schema};
@@ -458,6 +459,7 @@ mod tests {
     use crate::query::{ExecutableQuery, QueryBase};
     use crate::table::optimize::{CompactionOptions, OptimizeAction};
     use lance_index::scalar::FullTextSearchQuery;
+    use lance_index::scalar::inverted::query::{FtsQuery, MatchQuery};
 
     fn create_fixed_size_list<T: Array>(
         values: T,
@@ -599,6 +601,80 @@ mod tests {
         assert!(invalid_granularity.is_err());
     }
 
+    #[tokio::test]
+    async fn test_nested_list_fts_uses_deepest_document_coordinates() {
+        let conn = connect("memory://").execute().await.unwrap();
+        let mut docs = ListBuilder::new(ListBuilder::new(StringBuilder::new()));
+
+        docs.values().values().append_value("alpha");
+        docs.values().values().append_value("beta");
+        docs.values().append(true);
+        docs.values().values().append_value("gamma");
+        docs.values().values().append_value("alpha delta");
+        docs.values().append(true);
+        docs.append(true);
+
+        docs.values().append(true);
+        docs.values().values().append_value("alpha");
+        docs.values().append(true);
+        docs.append(true);
+
+        let batch = RecordBatch::try_from_iter(vec![
+            ("id", Arc::new(Int32Array::from(vec![0, 1])) as ArrayRef),
+            ("docs", Arc::new(docs.finish()) as ArrayRef),
+        ])
+        .unwrap();
+        let table = conn.create_table("nested", batch).execute().await.unwrap();
+
+        let job = table
+            .create_index(
+                &["docs"],
+                Index::FTS(
+                    FtsIndexBuilder::default()
+                        .document_granularity(DocumentGranularity::ListElement),
+                ),
+            )
+            .execute_async()
+            .await
+            .unwrap();
+        job.wait().await.unwrap();
+
+        let query = FullTextSearchQuery::new_query(FtsQuery::Match(
+            MatchQuery::new("alpha".to_string())
+                .with_column(Some("docs".to_string()))
+                .with_document_granularity(DocumentGranularity::ListElement),
+        ));
+        let batches = table
+            .query()
+            .full_text_search(query)
+            .limit(10)
+            .execute()
+            .await
+            .unwrap()
+            .try_collect::<Vec<_>>()
+            .await
+            .unwrap();
+
+        let mut hits = Vec::new();
+        for batch in batches {
+            let ids = batch["id"].as_any().downcast_ref::<Int32Array>().unwrap();
+            let coordinates = batch["_doc_index"]
+                .as_any()
+                .downcast_ref::<ListArray>()
+                .unwrap();
+            for row in 0..batch.num_rows() {
+                let coordinate = coordinates.value(row);
+                let coordinate = coordinate.as_any().downcast_ref::<UInt32Array>().unwrap();
+                hits.push((ids.value(row), coordinate.values().to_vec()));
+            }
+        }
+        hits.sort_unstable();
+        assert_eq!(
+            hits,
+            vec![(0, vec![0, 0]), (0, vec![1, 1]), (1, vec![1, 0])]
+        );
+    }
+
     /// Concurrent waiters, and a wait issued after the job settled, all
     /// succeed once the build does.
     #[tokio::test]

rust/lancedb/src/utils/mod.rs

@@ -227,7 +227,7 @@ pub(crate) fn resolve_arrow_field_path(schema: &Schema, column: &str) -> Result<
 
 pub(crate) struct ResolvedFtsField {
     pub canonical_path: String,
-    pub field: Field,
+    pub terminal_field: Field,
     pub list_depth: usize,
 }
 
@@ -309,7 +309,7 @@ pub(crate) fn resolve_lance_fts_field_path(
     );
     Ok(ResolvedFtsField {
         canonical_path,
-        field: Field::from(field),
+        terminal_field: Field::from(terminal),
         list_depth,
     })
 }
@@ -375,7 +375,7 @@ pub(crate) fn resolve_arrow_fts_field_path(
             message: format!("Invalid schema: {}", e),
         })?;
     let resolved = resolve_lance_fts_field_path(&lance_schema, column)?;
-    Ok((resolved.canonical_path, resolved.field))
+    Ok((resolved.canonical_path, resolved.terminal_field))
 }
 
 pub fn supported_btree_data_type(dtype: &DataType) -> bool {
@@ -647,8 +647,9 @@ mod tests {
             Field::new("docs", text_list(), true),
         ]);
 
-        let (path, _) = resolve_arrow_fts_field_path(&schema, "docs.content").unwrap();
+        let (path, field) = resolve_arrow_fts_field_path(&schema, "docs.content").unwrap();
         assert_eq!(path, "docs.content");
+        assert_eq!(field.data_type(), &DataType::Utf8);
 
         let lance_schema = lance_core::datatypes::Schema::try_from(&schema).unwrap();
         let field_id = lance_schema