feat(typescript): add table branch support

nodejs/__test__/table.test.ts

@@ -85,6 +85,39 @@ describe.each([arrow15, arrow16, arrow17, arrow18])(
       await expect(table.countRows()).resolves.toBe(3);
     });
 
+    it("should support branches", async () => {
+      await table.add([{ id: 1 }]);
+      expect(await table.countRows()).toBe(1);
+
+      // fork an isolated, writable branch from main
+      const branch = await (await table.branches()).create("exp");
+      expect(await branch.countRows()).toBe(1);
+      await branch.add([{ id: 2 }]);
+      expect(await branch.countRows()).toBe(2);
+      // main is untouched by branch writes
+      expect(await table.countRows()).toBe(1);
+
+      // listed, with main (null) as the parent
+      const list = await (await table.branches()).list();
+      expect(Object.keys(list)).toContain("exp");
+      expect(list["exp"].parentBranch).toBeNull();
+
+      // fromRef="main" is equivalent to the default
+      await (await table.branches()).create("exp2", "main");
+      const list2 = await (await table.branches()).list();
+      expect(list2["exp2"].parentBranch).toBeNull();
+
+      // checkout returns a handle scoped to the branch's latest
+      const checkedOut = await (await table.branches()).checkout("exp");
+      expect(await checkedOut.countRows()).toBe(2);
+
+      // delete removes it
+      await (await table.branches()).delete("exp");
+      await (await table.branches()).delete("exp2");
+      const after = await (await table.branches()).list();
+      expect(Object.keys(after)).not.toContain("exp");
+    });
+
     it("should show table stats", async () => {
       await table.add([{ id: 1 }, { id: 2 }]);
       await table.add([{ id: 1 }]);

nodejs/lancedb/table.ts

@@ -25,10 +25,12 @@ import {
   AddColumnsSql,
   AddResult,
   AlterColumnsResult,
+  BranchContents,
   DeleteResult,
   DropColumnsResult,
   IndexConfig,
   IndexStatistics,
+  Branches as NativeBranches,
   OptimizeStats,
   TableStatistics,
   Tags,
@@ -653,6 +655,14 @@ export abstract class Table {
    */
   abstract tags(): Promise<Tags>;
 
+  /**
+   * Get the branch manager for this table.
+   *
+   * Branches are isolated, writable lines of history forked from another
+   * branch (or version). Writes on a branch do not affect `main`.
+   */
+  abstract branches(): Promise<Branches>;
+
   /**
    * Restore the table to the currently checked out version
    *
@@ -1108,6 +1118,10 @@ export class LocalTable extends Table {
     return await this.inner.tags();
   }
 
+  async branches(): Promise<Branches> {
+    return new Branches(await this.inner.branches());
+  }
+
   async optimize(options?: Partial<OptimizeOptions>): Promise<OptimizeStats> {
     let cleanupOlderThanMs;
     if (
@@ -1238,3 +1252,47 @@ export interface FieldMetadataUpdate {
   /** If true, replace the field's entire metadata map instead of merging. */
   replace?: boolean;
 }
+
+/**
+ * Branch manager for a {@link Table}.
+ *
+ * Unlike tags, `create` and `checkout` return a new {@link Table} handle scoped
+ * to the branch; writes on it do not affect `main`.
+ */
+export class Branches {
+  private readonly inner: NativeBranches;
+
+  constructor(inner: NativeBranches) {
+    this.inner = inner;
+  }
+
+  /** List all branches, mapping name to branch metadata. */
+  async list(): Promise<Record<string, BranchContents>> {
+    return await this.inner.list();
+  }
+
+  /**
+   * Create a branch and return a handle scoped to it.
+   *
+   * @param name Name of the new branch.
+   * @param fromRef Source branch to fork from. Defaults to `main`.
+   * @param fromVersion A specific version on `fromRef`. Defaults to latest.
+   */
+  async create(
+    name: string,
+    fromRef?: string,
+    fromVersion?: number,
+  ): Promise<Table> {
+    return new LocalTable(await this.inner.create(name, fromRef, fromVersion));
+  }
+
+  /** Check out an existing branch and return a handle scoped to it. */
+  async checkout(name: string): Promise<Table> {
+    return new LocalTable(await this.inner.checkout(name));
+  }
+
+  /** Delete a branch. */
+  async delete(name: string): Promise<void> {
+    return await this.inner.delete(name);
+  }
+}

nodejs/src/table.rs

@@ -7,7 +7,7 @@ use lancedb::ipc::{ipc_file_to_batches, ipc_file_to_schema};
 use lancedb::table::{
     AddDataMode, ColumnAlteration as LanceColumnAlteration, Duration,
     FieldMetadataUpdate as LanceFieldMetadataUpdate, NewColumnTransform, OptimizeAction,
-    OptimizeOptions, Table as LanceDbTable,
+    OptimizeOptions, Ref, Table as LanceDbTable,
 };
 use napi::bindgen_prelude::*;
 use napi::threadsafe_function::{ThreadsafeFunction, ThreadsafeFunctionCallMode};
@@ -478,6 +478,13 @@ impl Table {
         })
     }
 
+    #[napi(catch_unwind)]
+    pub async fn branches(&self) -> napi::Result<Branches> {
+        Ok(Branches {
+            inner: self.inner_ref()?.clone(),
+        })
+    }
+
     #[napi(catch_unwind)]
     pub async fn optimize(
         &self,
@@ -1060,6 +1067,13 @@ pub struct TagContents {
     pub manifest_size: i64,
 }
 
+#[napi]
+pub struct BranchContents {
+    pub parent_branch: Option<String>,
+    pub parent_version: i64,
+    pub manifest_size: i64,
+}
+
 #[napi]
 pub struct Tags {
     inner: LanceDbTable,
@@ -1128,3 +1142,60 @@ impl Tags {
             .default_error()
     }
 }
+
+#[napi]
+pub struct Branches {
+    inner: LanceDbTable,
+}
+
+#[napi]
+impl Branches {
+    #[napi]
+    pub async fn list(&self) -> napi::Result<HashMap<String, BranchContents>> {
+        let branches = self.inner.list_branches().await.default_error()?;
+        let result = branches
+            .into_iter()
+            .map(|(k, v)| {
+                (
+                    k,
+                    BranchContents {
+                        parent_branch: v.parent_branch,
+                        parent_version: v.parent_version as i64,
+                        manifest_size: v.manifest_size as i64,
+                    },
+                )
+            })
+            .collect();
+        Ok(result)
+    }
+
+    #[napi]
+    pub async fn create(
+        &self,
+        name: String,
+        from_ref: Option<String>,
+        from_version: Option<i64>,
+    ) -> napi::Result<Table> {
+        // "main" and None are two spellings of the root branch; normalize so
+        // from_ref = "main" behaves identically to the default.
+        let from_ref = from_ref.filter(|b| b != "main");
+        let from = Ref::Version(from_ref, from_version.map(|v| v as u64));
+        let table = self
+            .inner
+            .create_branch(&name, from)
+            .await
+            .default_error()?;
+        Ok(Table::new(table))
+    }
+
+    #[napi]
+    pub async fn checkout(&self, name: String) -> napi::Result<Table> {
+        let table = self.inner.checkout_branch(&name).await.default_error()?;
+        Ok(Table::new(table))
+    }
+
+    #[napi]
+    pub async fn delete(&self, name: String) -> napi::Result<()> {
+        self.inner.delete_branch(&name).await.default_error()
+    }
+}