feat: add list_indices to the async api (#1074)

nodejs/__test__/table.test.ts

@@ -121,7 +121,12 @@ describe("When creating an index", () => {
     // check index directory
     const indexDir = path.join(tmpDir.name, "test.lance", "_indices");
     expect(fs.readdirSync(indexDir)).toHaveLength(1);
-    // TODO: check index type.
+    const indices = await tbl.listIndices();
+    expect(indices.length).toBe(1);
+    expect(indices[0]).toEqual({
+      indexType: "IvfPq",
+      columns: ["vec"],
+    });
 
     // Search without specifying the column
     const rst = await tbl.query().nearestTo(queryVec).limit(2).toArrow();

nodejs/lancedb/native.d.ts

@@ -3,6 +3,18 @@
 
 /* auto-generated by NAPI-RS */
 
+/** A description of an index currently configured on a column */
+export interface IndexConfig {
+  /** The type of the index */
+  indexType: string
+  /**
+   * The columns in the index
+   *
+   * Currently this is always an array of size 1.  In the future there may
+   * be more columns to represent composite indices.
+   */
+  columns: Array<string>
+}
 /**
  *  A definition of a column alteration. The alteration changes the column at
  * `path` to have the new name `name`, to be nullable if `nullable` is true,
@@ -122,4 +134,5 @@ export class Table {
   checkout(version: number): Promise<void>
   checkoutLatest(): Promise<void>
   restore(): Promise<void>
+  listIndices(): Promise<Array<IndexConfig>>
 }

nodejs/lancedb/table.ts

@@ -16,12 +16,14 @@ import { Schema, tableFromIPC } from "apache-arrow";
 import {
   AddColumnsSql,
   ColumnAlteration,
+  IndexConfig,
   Table as _NativeTable,
 } from "./native";
 import { Query } from "./query";
 import { IndexOptions } from "./indices";
 import { Data, fromDataToBuffer } from "./arrow";
 
+export { IndexConfig } from "./native";
 /**
  * Options for adding data to a table.
  */
@@ -342,4 +344,11 @@ export class Table {
   async restore(): Promise<void> {
     await this.inner.restore();
   }
+
+  /**
+   * List all indices that have been created with Self::create_index
+   */
+  async listIndices(): Promise<IndexConfig[]> {
+    return await this.inner.listIndices();
+  }
 }

nodejs/src/table.rs

@@ -257,6 +257,40 @@ impl Table {
     pub async fn restore(&self) -> napi::Result<()> {
         self.inner_ref()?.restore().await.default_error()
     }
+
+    #[napi]
+    pub async fn list_indices(&self) -> napi::Result<Vec<IndexConfig>> {
+        Ok(self
+            .inner_ref()?
+            .list_indices()
+            .await
+            .default_error()?
+            .into_iter()
+            .map(IndexConfig::from)
+            .collect::<Vec<_>>())
+    }
+}
+
+#[napi(object)]
+/// A description of an index currently configured on a column
+pub struct IndexConfig {
+    /// The type of the index
+    pub index_type: String,
+    /// The columns in the index
+    ///
+    /// Currently this is always an array of size 1.  In the future there may
+    /// be more columns to represent composite indices.
+    pub columns: Vec<String>,
+}
+
+impl From<lancedb::index::IndexConfig> for IndexConfig {
+    fn from(value: lancedb::index::IndexConfig) -> Self {
+        let index_type = format!("{:?}", value.index_type);
+        Self {
+            index_type,
+            columns: value.columns,
+        }
+    }
 }
 
 ///  A definition of a column alteration. The alteration changes the column at