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checkout

Update DVC-tracked files and directories in the workspace based on current dvc.lock and .dvc files.

Synopsis

usage: dvc checkout [-h] [-q | -v] [--summary] [-d] [-R] [-f]
                    [--relink]
                    [targets [targets ...]]

positional arguments:
  targets       Limit command scope to these tracked files/directories,
                .dvc files, or stage names.

Description

This command is usually needed after git checkout, git clone, or any other operation that changes the current dvc.lock or .dvc files in the project. It restores the corresponding versions of all DVC-tracked data files and directories from the cache to the workspace.

The targets given to this command (if any) limit what to checkout. It accepts paths to tracked files or directories (including paths inside tracked directories), .dvc files, and stage names (found in dvc.yaml).

The execution of dvc checkout does the following:

  • Checks dvc.lock and .dvc files to compare the hash values of their outputs against the actual files or directories in the workspace (similar to dvc status).

    Stage outputs must be defined in dvc.yaml (and dvc.lock contain their hash values), or they'll be skipped with a warning.

  • Missing data files or directories are restored from the cache. Those that don't match with dvc.lock or .dvc files are removed. See options --force and --relink. A list of the changes done is printed.

💡 For convenience, a Git hook is available to automate running dvc checkout after git checkout. See the Automating example below or dvc install for more details.

By default, this command tries not make copies of cached files in the workspace, using reflinks instead when supported by the file system (refer to File link types). The next linking strategy default value is copy though, so unless other file link types are manually configured in cache.type (using dvc config), files will be copied. Keep in mind that having file copies doesn't present much of a negative impact unless the project uses very large data (several GBs or more). But leveraging file links is crucial with large files, for example when checking out a 50Gb file by copying might take a few minutes whereas, with links, restoring any file size will be almost instantaneous.

When linking files takes longer than expected (10 seconds for any one file) and cache.type is not set, a warning will be displayed reminding users about the faster link types available. These warnings can be turned off setting the cache.slow_link_warning config option to false with dvc config cache.

This command will fail to checkout files that are missing from the cache. In such a case, dvc checkout prints a warning message. It also lists the partial progress made by the checkout.

There are two methods to restore a file missing from the cache, depending on the situation. In some cases the cache can be pulled from remote storage using dvc pull. In other cases the pipeline must be reproduced (using dvc repro) to regenerate its outputs.

Options

  • --summary - display a short summary of the changes done by this command in the workspace, instead of a full list of changes.

  • -d, --with-deps - only meaningful when specifying targets. This determines files to update by resolving all dependencies of the target stages or .dvc files: DVC searches backward from the targets in the corresponding pipelines. This will not checkout files referenced in later stages than the targets.

  • -R, --recursive - determines the files to checkout by searching each target directory and its subdirectories for dvc.lock and .dvc files to inspect. If there are no directories among the targets, this option has no effect.

  • -f, --force - does not prompt when removing workspace files. Changing the current set of DVC files with git checkout can result in the need for DVC to remove files that don't match those references or are missing from cache. (They are not "committed", in DVC terms.)

  • --relink - ensures the file linking strategy (reflink, hardlink, symlink, or copy) for all data in the workspace is consistent with the project's cache.type. This is achieved by restoring all data files or directories referenced in current DVC files (regardless of whether the files/dirs were already present).

  • -h, --help - shows the help message and exit.

  • -q, --quiet - do not write anything to standard output. Exit with 0 if no problems arise, otherwise 1.

  • -v, --verbose - displays detailed tracing information from executing the dvc pull command.

Examples

Let's employ a simple workspace with some data, code, ML models, pipeline stages, such as the DVC project created for the Get Started. Then we can see what happens with git checkout and dvc checkout as we switch from tag to tag.

Start by cloning our example repo if you don't already have it:

$ git clone https://github.com/iterative/example-get-started
$ cd example-get-started
$ dvc fetch -aT

We run dvc fetch with the -aT flags to get the DVC-tracked data from all Git branches and tags from remote storage to the cache. This way it's all available for the checkout examples below.

The workspace looks like this:

.
├── data
│   └── data.xml.dvc
├── dvc.lock
├── dvc.yaml
├── params.yaml
├── prc.json
├── scores.json
└── src
    └── <code files here>

Note that this repository includes the following tags, that represent different variants of the resulting model:

$ git tag
...
baseline-experiment     <- First simple version of the model
bigrams-experiment      <- Uses bigrams to improve the model

We can now run dvc checkout to update the most recent model.pkl, data.xml, and any other files tracked by DVC. The model file hash (ab349c2...) is saved in dvc.lock, and it can be confirmed with:

$ dvc checkout

$ md5 model.pkl
MD5 (data.xml) = ab349c2b5fa2a0f66d6f33f94424aebe

Example: Switch versions

What if we want to "rewind history", so to speak? The git checkout command lets us restore any commit in the repository history (including tags). It automatically adjusts the repo files, by replacing, adding, or deleting them as necessary.

$ git checkout baseline-experiment  # Git commit where model was created

Let's check the hash value of model.pkl in dvc.lock now:

outs:
  - path: model.pkl
    md5: 98af33933679a75c2a51b953d3ab50aa

But if you check the MD5 of model.pkl, the file hash is still the same (ab349c2...). This is because git checkout changed dvc.lock and other DVC files, but it did nothing with model.pkl, or any other DVC-tracked files/dirs. Since Git doesn't track them, to get them we can do this:

$ dvc checkout
M       model.pkl
M       data\features\

$ md5 model.pkl
MD5 (model.pkl) = 98af33933679a75c2a51b953d3ab50aa

DVC went through the stages (in dvc.yaml) and adjusted the current set of outputs to match the outs in the corresponding dvc.lock.

Example: Specific files or directories

dvc checkout only affects the tracked data corresponding to any given targets:

$ git checkout master
$ dvc checkout            # Start with latest version of everything.

$ git checkout baseline-experiment -- dvc.lock
$ dvc checkout model.pkl  # Get previous model file only.

Note that you can checkout data within directories tracked. For example, the featurize stage has the entire data/features directory as output, but we can just get this:

$ dvc checkout data/features/test.pkl

Example: Automating DVC checkout

We want the data files or directories (managed by DVC) to match with the other files (managed by Git e.g. source code). This requires us to remember running dvc checkout when needed after a git checkout, and we may not always remember to do so. Wouldn't it be nice to automate this?

$ dvc install

dvc install installs Git hooks to automate common operations, including running dvc checkout when needed.

(Having followed the previous example) we can then checkout the master branch again:

$ git checkout bigrams-experiment  # Has the latest model version

$ md5 model.pkl
MD5 (model.pkl) = ab349c2b5fa2a0f66d6f33f94424aebe

Previously this took two commands, git checkout followed by dvc checkout. We can now skip the second one, which is automatically run for us. The workspace files are automatically updated accordingly.

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