lancedb/docs/web/tables/branching.mdx

---
title: "Branches"
sidebarTitle: "Branch"
description: "Fork isolated, writable lines of table history in LanceDB. Run experiments, backfills, and index rebuilds without disturbing production reads on main."
icon: "code-branch"
---
import {
    PyConnect,
    TsConnect,
    RsConnect,
    PyConnectEnterpriseQuickstart,
    TsConnectEnterpriseQuickstart,
    RsConnectEnterpriseQuickstart,
} from '/snippets/connection.mdx';
import {
    PyBranchCreate as BranchCreate,
    TsBranchCreate,
    RsBranchCreate,
    PyBranchWrite as BranchWrite,
    TsBranchWrite,
    RsBranchWrite,
    PyBranchReopen as BranchReopen,
    TsBranchReopen,
    RsBranchReopen,
    PyBranchDelete as BranchDelete,
    TsBranchDelete,
    RsBranchDelete,
    PyBranchUpsertToMain as BranchUpsertToMain,
    TsBranchUpsertToMain,
    RsBranchUpsertToMain,
    PyBranchIndex as BranchIndex,
    TsBranchIndex,
    RsBranchIndex,
} from '/snippets/tables.mdx';

A branch is an isolated, writable line of history forked from `main` (or from any
other branch). Anything you do on a branch (e.g., adding rows, changing the schema,
building an index) stays on that branch, so `main` keeps serving production
reads exactly as before. Branches are a natural fit when you want to:

- Experiment with a new index, schema change, or reprocessing step without
  affecting live queries on `main`.
- Run a backfill or migration you'd like to validate before applying it to
  `main`.
- Hand a collaborator a frozen point-in-time fork while you keep writing to `main`.

## How branches relate to versions and tags {#how-branches-relate-to-versions-and-tags}

Every LanceDB table already tracks a linear history of [versions](/management/table#versioning),
and you can [tag](/management/table#versioning-tag-based-versioning) a version or `checkout`
one to read it. Branches add the missing piece: a *separate, writable* line of
history. Where a tag is a read-only label and `checkout` is a read-only view, a
branch forks from a point in history and then evolves on its own. Creating or
checking out a branch hands you a new table handle whose reads and writes are
scoped to that branch. The [comparison table](#branches-vs-tags-vs-checkout) at
the end of this page lays out when to reach for each.

<Note>
Branches are supported on local and namespace-backed tables in LanceDB OSS, as
well as on LanceDB Enterprise (remote) tables.
</Note>

## Connect to a table {#connect-to-a-table}

The branch API is identical no matter how you connect — only the connection
itself differs between OSS and Enterprise. Establish a connection (`db`) and open
a `table` (see [Ingesting data](/ingestion)), then use the same branch calls
in every example that follows.

### LanceDB OSS {#lancedb-oss}

Point LanceDB at a local directory (or an object-storage URI) to use it as an
embedded library.

<CodeGroup>
    <CodeBlock filename="Python" language="Python" icon="python">
    {PyConnect}
    </CodeBlock>

    <CodeBlock filename="TypeScript" language="TypeScript" icon="square-js">
    {TsConnect}
    </CodeBlock>

    <CodeBlock filename="Rust" language="Rust" icon="rust">
    { "use lancedb::connect;\n\n" }
    {RsConnect}
    </CodeBlock>
</CodeGroup>

### LanceDB Enterprise {#lancedb-enterprise}

<Badge color="red">Enterprise</Badge>

Branching on LanceDB Enterprise works the same way as on OSS, but you connect to your
Enterprise deployment with a `db://` URI, an API key, and your
region. Once you have a connection, open a table and use the same branch calls in
every example that follows.

<CodeGroup>
    <CodeBlock filename="Python" language="Python" icon="python">
    {PyConnectEnterpriseQuickstart}
    </CodeBlock>

    <CodeBlock filename="TypeScript" language="TypeScript" icon="square-js">
    {TsConnectEnterpriseQuickstart}
    </CodeBlock>

    <CodeBlock filename="Rust" language="Rust" icon="rust">
    {RsConnectEnterpriseQuickstart}
    </CodeBlock>
</CodeGroup>

## Work with branches {#work-with-branches}

The lifecycle of a branch is short and predictable: fork it, write to it, reopen
it whenever you need it, and delete it once you're done. The examples below use a
small `quotes` table with three rows on `main`.

### Create a branch {#create-a-branch}

Forking from `main` returns a table handle scoped to the new branch. `main` is
the reserved default source, so `create` needs only a name; to fork from
somewhere else, pass a branch name, a specific version, or both.

<CodeGroup>
    <CodeBlock filename="Python" language="Python" icon="python">
    {BranchCreate}
    </CodeBlock>

    <CodeBlock filename="TypeScript" language="TypeScript" icon="square-js">
    {TsBranchCreate}
    </CodeBlock>

    <CodeBlock filename="Rust" language="Rust" icon="rust">
    {RsBranchCreate}
    </CodeBlock>
</CodeGroup>

### Write to a branch {#write-to-a-branch}

Writes go through the branch handle and stay there — the `main` handle keeps
reporting its original row count. Listing branches returns a mapping of each
branch name to its metadata, including the version it was forked from.

<CodeGroup>
    <CodeBlock filename="Python" language="Python" icon="python">
    {BranchWrite}
    </CodeBlock>

    <CodeBlock filename="TypeScript" language="TypeScript" icon="square-js">
    {TsBranchWrite}
    </CodeBlock>

    <CodeBlock filename="Rust" language="Rust" icon="rust">
    {RsBranchWrite}
    </CodeBlock>
</CodeGroup>

### Reopen a branch {#reopen-a-branch}

A branch outlives the handle that created it. Reopen it later by name — either
from an existing table handle or straight from the connection when you open the
table. Both routes give you a writable handle tracking the branch's latest state.

<CodeGroup>
    <CodeBlock filename="Python" language="Python" icon="python">
    {BranchReopen}
    </CodeBlock>

    <CodeBlock filename="TypeScript" language="TypeScript" icon="square-js">
    {TsBranchReopen}
    </CodeBlock>

    <CodeBlock filename="Rust" language="Rust" icon="rust">
    {RsBranchReopen}
    </CodeBlock>
</CodeGroup>

### Delete a branch {#delete-a-branch}

Deleting a branch removes it and its branch-local history; `main` is untouched.
Before deleting a branch, make sure you've retained any results you need — see
[Apply branch-tested changes to `main`](#apply-branch-tested-changes-to-main)
below.

<CodeGroup>
    <CodeBlock filename="Python" language="Python" icon="python">
    {BranchDelete}
    </CodeBlock>

    <CodeBlock filename="TypeScript" language="TypeScript" icon="square-js">
    {TsBranchDelete}
    </CodeBlock>

    <CodeBlock filename="Rust" language="Rust" icon="rust">
    {RsBranchDelete}
    </CodeBlock>
</CodeGroup>

## Apply branch-tested changes to `main` {#apply-branch-tested-changes-to-main}

<Warning>
A branch has its own writable history. Outside of the [diff and merge
APIs](#compare-and-merge-a-branch-into-main) — which are available on
LanceDB Enterprise and promote added columns only — LanceDB does not reconcile
one branch's history with another or detect conflicts between them. To carry
other accepted work forward, rerun the validated operation against `main` or
explicitly write selected results to it.
</Warning>

How you apply a validated change depends on the type of work:

- **Added columns (Enterprise):** review the branch with `diff`, then promote
  the new columns onto `main` with `merge`. See
  [Compare and merge a branch into `main`](#compare-and-merge-a-branch-into-main).
- **Backfill or transformation:** rerun the validated job against `main`.
- **Schema change:** apply the same reviewed schema operation to `main`.
- **Index change:** build the index on `main` using the configuration validated
  on the branch.
- **Selected row results:** upsert those rows into `main` using a stable unique
  key.

### Upsert selected branch rows into `main` {#upsert-selected-branch-rows-into-main}

If the result you want to retain is a set of inserted or updated rows, use
[`merge_insert`](/ingestion/merge-insert#merge-incoming-rows-by-key) to write them to
`main`. Despite its name, `merge_insert` is a row-ingestion operation: it
matches incoming rows by key and does not merge branch histories.

Read the rows you want from the reviewed branch, then upsert them into `main` on
your key column — `id` in this example. Here, `candidate` is the branch handle:

<CodeGroup>
    <CodeBlock filename="Python" language="Python" icon="python">
    {BranchUpsertToMain}
    </CodeBlock>

    <CodeBlock filename="TypeScript" language="TypeScript" icon="square-js">
    {TsBranchUpsertToMain}
    </CodeBlock>

    <CodeBlock filename="Rust" language="Rust" icon="rust">
    {RsBranchUpsertToMain}
    </CodeBlock>
</CodeGroup>

This operation transfers only the inserted or updated rows in its input. It does
not transfer branch history, schema changes, indexes, or branch-local deletions,
and it does not determine which rows changed after the branch was created.

Reapplying an identical payload is idempotent on the key, but the operation is
not conflict-aware. If `main` has diverged, incoming branch rows can overwrite
newer values with the same key. Read and upsert the whole branch only when that
overwrite is intentional; otherwise, filter the branch read to the rows you
intend to apply.

## Compare and merge a branch into `main` {#compare-and-merge-a-branch-into-main}

<Badge color="red">Enterprise</Badge>

On LanceDB Enterprise, branches expose two review-and-land calls that let you
inspect what a branch has changed relative to `main` and then promote its new
columns onto `main` in place — without reissuing the branch's writes.

<Info>
`diff` and `merge` are available on Enterprise (remote) tables only. On local
tables both calls raise `NotSupported`. `merge` currently promotes added
columns; use the [upsert](#upsert-selected-branch-rows-into-main) or rerun
patterns above for row and index changes.
</Info>

### Diff a branch {#diff-a-branch}

`diff` reads the branch and `main`, and returns a summary of what has changed:
which columns were added, removed, or altered; which indexes were added or
removed; row-count deltas; and — most importantly — a list of merge blockers
explaining why the branch cannot currently be merged, if any.

<CodeGroup>
```python Python icon="python"
diff = table.branches.diff("exp")

print(diff["addedColumns"])       # columns the branch introduced
print(diff["mergeable"])          # True when there are no blockers
print(diff["mergeBlockers"])      # list of {"code", "message"} entries
```

```typescript TypeScript icon="square-js"
const diff = await table.branches.diff("exp");

console.log(diff.addedColumns);   // columns the branch introduced
console.log(diff.mergeable);      // true when there are no blockers
console.log(diff.mergeBlockers);  // array of { code, message } entries
```
</CodeGroup>

Common merge blocker codes include `BaseMoved` (the branch's parent no longer
matches `main`'s latest), `RowsChanged`, `ColumnRemoved`, `ColumnChanged`,
`NoMergeableChanges`, `NoColumnChanges`, `InputColumnDependency`, and
`ParentNotMain`. Newer server codes surface as `Unknown` so older clients
keep working.

### Merge a branch {#merge-a-branch}

`merge` promotes a branch's added columns onto `main`. It is a review-and-land
operation: the server re-evaluates the diff at request time, and either lands
the promotion or rejects it with the same blockers `diff` would report. A
rejected merge is not an exception — it resolves with `status="rejected"` so
you can inspect the blockers and decide what to do next.

Set `dry_run=True` (Python) or `dryRun: true` (TypeScript) to preview the
merge without landing it. The result includes a `preview.promoted_columns`
list showing which columns the merge would (or did) promote.

<CodeGroup>
```python Python icon="python"
# Preview first — this does not modify main.
preview = table.branches.merge("exp", dry_run=True)
print(preview["status"])                   # "ready" | "rejected" | ...
print(preview["preview"]["promotedColumns"])

# Land the merge.
result = table.branches.merge("exp")
if result["status"] == "merged":
    print("landed at main version", result["mainVersionAfter"])
elif result["status"] == "rejected":
    for blocker in result["diff"]["mergeBlockers"]:
        print(blocker["code"], blocker["message"])
```

```typescript TypeScript icon="square-js"
// Preview first — this does not modify main.
const preview = await table.branches.merge("exp", true);
console.log(preview.status);               // "ready" | "rejected" | ...
console.log(preview.preview.promotedColumns);

// Land the merge.
const result = await table.branches.merge("exp");
if (result.status === "merged") {
  console.log("landed at main version", result.mainVersionAfter);
} else if (result.status === "rejected") {
  for (const blocker of result.diff.mergeBlockers) {
    console.log(blocker.code, blocker.message);
  }
}
```
</CodeGroup>

Possible `status` values are `ready` (returned by `dry_run` when the merge
would land), `merged` (a real merge that landed), `rejected` (server declined;
see `diff.mergeBlockers`), `notImplemented`, and `unknown` for forward
compatibility. Merge requests are not retried on rejection — the response
carries everything you need to decide next steps.

## Build indexes on a branch {#build-indexes-on-a-branch}

One of the most useful things a branch buys you is a safe place to build and
validate an index without affecting what's in production on the `main` branch.
Fork a branch, create your vector (ANN) and full-text search (FTS)
indexes on it, and check recall and latency. Once you have selected a
configuration, build the corresponding index on `main` through your normal
deployment workflow. Because the indexes live on the branch, queries against
`main` never see a half-built index and are never slowed down by the branch's
build.

This pattern is especially valuable on <Badge color="red">Enterprise</Badge>
deployments, where `main` is typically serving production traffic while you tune
an index configuration on the side.

<CodeGroup>
    <CodeBlock filename="Python" language="Python" icon="python">
    {BranchIndex}
    </CodeBlock>

    <CodeBlock filename="TypeScript" language="TypeScript" icon="square-js">
    {TsBranchIndex}
    </CodeBlock>

    <CodeBlock filename="Rust" language="Rust" icon="rust">
    {RsBranchIndex}
    </CodeBlock>
</CodeGroup>

Schema changes such as adding, altering, or dropping columns are branch-scoped in
the same way, so you can stage and review a larger reshaping of a table before
applying the same schema operations to `main`.

## Branches vs. tags vs. versions {#branches-vs-tags-vs-versions}

Now that you're familiar with branches, you can see how they complement the other ways LanceDB
give you to work with table history. Choose these approaches based on whether you need to
*label*, *read*, or *write* data at a point in history:

| Feature | Writable? | Purpose |
| --- | --- | --- |
| **[Branch](#work-with-branches)** | ✅ Yes | Write on top of a point in history without touching `main`. |
| **[Tag](/management/table#versioning-tag-based-versioning)** | ❌ No | Attach a human-readable label to an existing version; protects it from cleanup. |
| **[`checkout(version)`](/management/table#versioning-rollback-to-previous-versions)** | ❌ No | Read a historical version of `main` without forking. Read-only until you `restore`. |

<Note>
For linear version history — creating versions, listing them, rolling back, and
tagging — see the [Versioning and Reproducibility](/management/table#versioning) guide.
</Note>