# Creating Multiple Changesets in Large Repositories

<p className="subtitle">
	Learn how to create multiple changesets in large-sized repos.
</p>

<Callout type="note">
	Creating multiple changesets in large repos functionality is in the Beta
	stage.
</Callout>

Batch changes can produce a lot of changes in a single repository. Splitting the changes into multiple changesets makes reviewing and merging the changes easier.

This can be done by using [`transformChanges`](/batch-changes/batch-spec-yaml-reference#transformchanges) in the batch spec to group the changes produced in one single repository by directory and create a changeset for each group.

<Callout type="note">
	In some monorepos, it makes more sense to run the batch spec `steps` per
	project. Read [Creating changesets per project in
	monorepos](/batch-changes/creating-changesets-per-project-in-monorepos)to
	find out how to use the `workspaces` property for it.
</Callout>

## Using `transformChanges`

The following batch spec uses the `transformChanges` property to create up to 4 changesets in a single repository by grouping the changes made in different directories:

```yaml
name: hello-world
description: Add Hello World to READMEs

# Find all repositories that contain a README file.
on:
    - repositoriesMatchingQuery: file:README

# In each repository, run this command. Each repository's resulting diff is captured.
steps:
    - run: IFS=$'\n'; echo Hello World | tee -a $(find -name README)
      container: alpine:3

# Transform the changes produced in each repository.
transformChanges:
    # Group the file diffs by directory and produce one additional changeset per group.
    # Changes that haven't been grouped will be be in the standard changeset.
    group:
        - directory: client
          branch: hello-world-client # will replace the `branch` in the `changesetTemplate`
        - directory: docker-images
          # Optional: only apply the rule in this repository
          repository: github.com/sourcegraph/sourcegraph
          branch: hello-world-infra
        - directory: monitoring
          repository: github.com/sourcegraph/sourcegraph
          branch: hello-world-monitoring

# Describe the changeset (e.g., GitHub pull request) you want for each repository.
changesetTemplate:
    title: Hello World
    body: My first batch change!
    branch:
        hello-world # This branch is the default branch and will be
        # overwritten for each additional changeset.
    commit:
        message: Append Hello World to all README files
    published: false # Do not publish any changes to the code hosts yet
```

This batch spec will produce up to 4 changesets in the `github.com/sourcegraph/sourcegraph` repository:

1. A changeset with the changes in the `client` directory
1. A changeset with the changes in `docker-images`
1. A changeset with the changes in `monitoring`
1. A changeset with the changes in the other directories.

Since code hosts and Git don't allow creating multiple, different changesets on the same branch, it is **required** to specify a unique `branch` for each `directory` that will be used for the additional changesets. That `branch` will overwrite the default branch specified in `changesetTemplate`.

If no changes have been made in a `directory` specified in a `group`, no additional changeset will be produced. If the optional `repository` property is specified, only the changes in that repository will be grouped.

<Callout type="info">
	Read more in [batch spec YAML reference about
	`transformChanges`](/batch-changes/batch-spec-yaml-reference#transformchanges).
</Callout>