Dolt Branches

In this example, we’ll show how to use DoltTable along with Dolt’s Branch feature.

import os
import sys
import typing

from dolt_integrations.core import NewBranch
from flytekitplugins.dolt.schema import DoltConfig, DoltTable
from flytekit import task, workflow
import pandas as pd

A Simple Workflow

We will run a simple data workflow:

  1. Create a users table with name and count columns.

  2. Filter the users table for users with count > 5.

  3. Record the filtered users’ names in a big_users table.

Database Configuration

Let’s define our database configuration. Our DoltConfig references a foo folder containing our database. Use either a tablename or a sql select statement to fetch data.

doltdb_path = os.path.join(os.path.dirname(__file__), "foo")

def generate_confs(a: int) -> typing.Tuple[DoltConfig, DoltConfig, DoltConfig]:
    users_conf = DoltConfig(
        db_path=doltdb_path,
        tablename="users",
        branch_conf=NewBranch(f"run/a_is_{a}")
    )

    query_users = DoltTable(
        config=DoltConfig(
            db_path=doltdb_path,
            sql="select * from users where `count` > 5",
            branch_conf=NewBranch(f"run/a_is_{a}"),
        ),
    )

    big_users_conf = DoltConfig(
        db_path=doltdb_path,
        tablename="big_users",
        branch_conf=NewBranch(f"run/a_is_{a}"),
    )

    return users_conf, query_users, big_users_conf

Tip

A DoltTable is an extension of DoltConfig that wraps a pandas.DataFrame – accessible via the DoltTable.data attribute at execution time.

Type Annotating Tasks and Workflows

We can turn our data processing pipeline into a Flyte workflow by decorating functions with the task() and workflow() decorators. Annotating the inputs and outputs of those functions with Dolt schemas indicates how to save and load data between tasks.

The DoltTable.data attribute loads dataframes for input arguments. Return types of DoltTable save the data to the Dolt database given a connection configuration.

@task
def get_confs(a: int) -> typing.Tuple[DoltConfig, DoltTable, DoltConfig]:
    return generate_confs(a)

@task
def populate_users(a: int, conf: DoltConfig) -> DoltTable:
    users = [("George", a), ("Alice", a*2), ("Stephanie", a*3)]
    df = pd.DataFrame(users, columns=["name", "count"])
    return DoltTable(data=df, config=conf)

@task
def filter_users(a: int, all_users: DoltTable, filtered_users: DoltTable, conf: DoltConfig) -> DoltTable:
    usernames = filtered_users.data[["name"]]
    return DoltTable(data=usernames, config=conf)

@task
def count_users(users: DoltTable) -> int:
    return users.data.shape[0]

@workflow
def wf(a: int) -> int:
    user_conf, query_conf, big_user_conf = get_confs(a=a)
    users = populate_users(a=a, conf=user_conf)
    big_users = filter_users(a=a, all_users=users, filtered_users=query_conf, conf=big_user_conf)
    big_user_cnt = count_users(users=big_users)
    return big_user_cnt

if __name__ == "__main__":
    print(f"Running {__file__} main...")
    if len(sys.argv) != 2:
        raise ValueError("Expected 1 argument: a (int)")
    a = int(sys.argv[1])
    result = wf(a=a)
    print(f"Running wf(), returns int\n{result}\n{type(result)}")

We will run this workflow twice:

python branch_example.py 2
python branch_example.py 3

Which creates distinct branches for our two a values:

cd foo
dolt branch

Total running time of the script: ( 0 minutes 0.000 seconds)

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