Access Unity tables via the Iceberg Rest Api

After working with glue catalog in the previous article, i wanted it to test with Unity Catalog. The opensource catalog from DataBricks.

Installing Unity Catalog

I followed the quickstart steps from: https://docs.unitycatalog.io/quickstart/. It needs java 17, my mac installation had 23 installed by default. I used the following with jenv to switch quickly

Install java 17 from brew with jenv

brew install microsoft-openjdk@17 jenv
jenv add /opt/homebrew/opt/openjdk@17

Clone repo and setup java to 17

git clone [email protected]:unitycatalog/unitycatalog.git
cd unitycatalog
jenv local 17
jenv rehash

Start (and build the first):

bin/start-uc-server

Use Uniform tables

Unity is not supporting native iceberg yet. But it does support the uniform delta format which can be used with delta and iceberg

To setup the test environment follow: https://docs.unitycatalog.io/usage/tables/uniform/

cp -r etc/data/external/unity/default/tables/marksheet_uniform /tmp/marksheet_uniform

Rest Api

The iceberg api is available from: http://127.0.0.1:8080/api/2.1/unity-catalog/iceberg/

According the documentation the tables can be used with the following format, but i had to change this

When querying Iceberg REST Catalog for Unity Catalog, tables are identified using the following pattern iceberg... (e.g. iceberg.unity.default.marksheet_uniform).

Code

By default the local unity catalog doesn’t use authentication. I’ll test this later.

from pyiceberg.catalog import load_catalog
import logging


def main():
    rest_catalog = load_catalog(
    "databricks",
    **{
        "type": "rest",
        "warehouse": "unity",
        "uri": "http://127.0.0.1:8080/api/2.1/unity-catalog/iceberg",
    }
    )
    print(rest_catalog.list_namespaces())
    print(rest_catalog.list_tables("default"))
    print(rest_catalog.load_table("default.marksheet_uniform").scan().to_pandas())


if __name__ == "__main__":
    main()

Output

2024-12-29 12:53:45,806 - urllib3.connectionpool - DEBUG - Starting new HTTP connection (1): 127.0.0.1:8080
2024-12-29 12:53:45,809 - urllib3.connectionpool - DEBUG - http://127.0.0.1:8080 "GET /api/2.1/unity-catalog/iceberg/v1/config?warehouse=unity HTTP/1.1" 200 55
2024-12-29 12:53:45,810 - urllib3.connectionpool - DEBUG - Starting new HTTP connection (1): 127.0.0.1:8080
2024-12-29 12:53:45,815 - urllib3.connectionpool - DEBUG - http://127.0.0.1:8080 "GET /api/2.1/unity-catalog/iceberg/v1/catalogs/unity/namespaces HTTP/1.1" 200 28
[('default',)]
2024-12-29 12:53:45,836 - urllib3.connectionpool - DEBUG - http://127.0.0.1:8080 "GET /api/2.1/unity-catalog/iceberg/v1/catalogs/unity/namespaces/default/tables HTTP/1.1" 200 70
[('default', 'marksheet_uniform')]
2024-12-29 12:53:45,853 - urllib3.connectionpool - DEBUG - http://127.0.0.1:8080 "GET /api/2.1/unity-catalog/iceberg/v1/catalogs/unity/namespaces/default/tables/marksheet_uniform HTTP/1.1" 200 2238
2024-12-29 12:53:45,853 - pyiceberg.io - INFO - Defaulting to PyArrow FileIO
    id        name  marks
0    1  nWYHawtqUw    930
1    2  uvOzzthsLV    166
2    3  WIAehuXWkv    170
3    4  wYCSvnJKTo    709

Difference

It seems the implementation is slightly different that the glue iceberg catalog and also not fully features.

Only “issue” is that the setup requests a parameter warehouse in the setup. I pass this in the config with "warehouse": "unity" Where warehouse is the same as catalog.

After that it responds the same as the glue iceberg catalog rest api. I’m able to list the namespace, tables and view the data.

For the full source code, this can be found here: https://github.com/unitycatalog/unitycatalog/blob/main/server/src/main/java/io/unitycatalog/server/service/IcebergRestCatalogService.java

Next

1. Writing data
2. Trying real iceberg tables
3. Comparing functionality off the rest api’s.