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Importing data from S3

Table of contents

  1. Copying using external tools
  2. Limitations
  3. Using lakeFS import tool
    1. Prerequisites
    2. Using the import tool
      1. Merging imported data to the main branch
    3. Gradual Import
    4. Limitations

Copying using external tools

In order to import existing data to lakeFS, you may choose to copy it using S3 CLI or using tools like Apache DistCp. This is the most straightforward way, and we recommend it if it’s applicable for you.

Limitations

Unfortunately, copying data is not always feasible for the following reasons:

  1. Some data is just too big to copy.
  2. It requires you to stop making changes to the data before starting to copy.
  3. It requires you to switch to using the lakeFS endpoint in all places at once.

Using lakeFS import tool

To solve this we offer an import tool that does not copy any data, allowing for a more gradual onboarding process.

The lakeFS import tool will use the S3 Inventory feature to create lakeFS metadata. The imported metadata will be reflected in lakeFS under a special branch, called import-from-inventory. You should not make any changes or commit anything to this branch: it will be operated on only by lakeFS. After importing, you will be able to merge this branch into your main branch.

The imported data is not copied to the repository’s dedicated bucket. Rather, it will be read directly from your existing bucket when you access it through lakeFS. Files created or replaced through lakeFS will then be stored in the repository’s dedicated bucket.

It is important to note that due to the deduplication feature of lakeFS, data will stay in your original bucket even when accessing it through other branches. In a sense, your original bucket becomes an initial snapshot of your data.

Note: lakeFS will never make any changes to the import source bucket.

Prerequisites

  • Your bucket should have S3 Inventory enabled.
  • The inventory should be in Parquet or ORC format.
  • The inventory must contain (at least) the size, last-modified-at, and e-tag columns.
  • The S3 credentials you provided to lakeFS should have GetObject permissions on the source bucket and on the bucket where the inventory is stored.
  • If you want to use the tool for gradual import, you should not delete the data for the most recently imported inventory, until a more recent inventory is successfully imported.

Using the import tool

Import is performed by lakefs ‘s import command.

Assuming your manifest.json is at s3://example-bucket/path/to/inventory/YYYY-MM-DDT00-00Z/manifest.json, and your lakeFS configuration yaml is at config.yaml (see notes below), run the following command to start the import:

lakefs import lakefs://example-repo -m s3://example-bucket/path/to/inventory/YYYY-MM-DDT00-00Z/manifest.json --config config.yaml

You will see the progress of your import as it is performed. After the import is finished, a summary will be printed along with suggestions for commands to access your data.

Added or changed objects: 565000
Deleted objects: 0
Commit ref: ~AcT47Svc1Q3MqayUwSqETVW9JRerMzAq6

Import to branch import-from-inventory finished successfully.
To list imported objects, run:
	$ lakectl fs ls lakefs://example-repo@~AcT47Svc1Q3MqayUwSqETVW9JRerMzAq6/
To merge the changes to your main branch, run:
	$ lakectl merge lakefs://example-repo@import-from-inventory lakefs://goo@master

Merging imported data to the main branch

As previously mentioned, the above command imports data to the dedicated import-from-inventory branch. By adding the --with-merge flag to the import command, this branch will be automatically merged to your main branch immediately after the import.

lakefs import --with-merge lakefs://example-repo -m s3://example-bucket/path/to/inventory/YYYY-MM-DDT00-00Z/manifest.json --config config.yaml

Notes

  1. Perform the import from a machine with access to your database, and on the same region of your destination bucket.

  2. You can download the lakefs binary from here. Make sure you choose one compatible with your installation of lakeFS.

  3. Use a configuration file like the one used to start your lakeFS installation. This will be used to access your database. An example can be found here.

Warning: the import-from-inventory branch should only be used by lakeFS. You should not make any operations on it.

Gradual Import

Once you switch to using the lakeFS S3-compatible endpoint in all places, you can stop making changes to your original bucket. However, if your operation still requires that you work on the original bucket, you can repeat using the import API with up-to-date inventories every day, until you complete the onboarding process. The changes will be added as new commits to the import-from-inventory branch, which you can in turn merge into your main branch.

Limitations

Note that lakeFS cannot manage your metadata if you make changes to data in the original bucket. The following table describes the results of making changes in the original bucket, without importing it to lakeFS:

Object action in the original bucket ListObjects result in lakeFS GetObject result in lakeFS
Create Object not visible Object not accessible
Overwrite Object visible with outdated metadata Updated object accessible
Delete Object visible Object not accessible