Chronon Python API
Overview
Chronon Python API for materializing configs to be run by the Chronon Engine. Contains python helpers to help managed a repo of feature and join definitions to be executed by the chronon scala engine.
User API Overview
Sources
Most fields are self explanatory. Time columns are expected to be in milliseconds (unixtime).
# File <repo>/sources/sample_sources.py
from ai.chronon.query import (
Query,
select,
)
from ai.chronon.source import EventSource, EntitySource
# Sample query
Query(
selects=select(
user="user_id",
created_at="created_at",
),
wheres=["has_availability = 1"],
start_partition="2021-01-01", # Defines the beginning of time for computations related to the source.
setups=["...UDF..."],
time_column="ts",
end_partition=None,
mutation_time_column="mutation_timestamp",
reversal_column="CASE WHEN mutation_type IN ('DELETE', 'UPDATE_BEFORE') THEN true ELSE false END"
)
user_activity = EntitySource(
snapshot_table="db_exports.table",
mutation_table="mutations_namespace.table_mutations",
mutation_topic="mutationsKafkaTopic",
query=Query(...)
)
website__views = EventSource(
table="namespace.table",
topic="kafkaTopicForEvents",
)
Group By (Features)
Group Bys are aggregations over sources that define features. For example:
# File <repo>/group_bys/example_team/example_group_by.py
from ai.chronon.group_by import (
GroupBy,
Window,
TimeUnit,
Accuracy,
Operation,
Aggregations,
Aggregation,
DefaultAggregation,
)
from sources import sample_sources
sum_cols = [f"active_{x}_days" for x in [30, 90, 120]]
v0 = GroupBy(
sources=test_source.user_activity,
keys=["user"],
aggregations=Aggregations(
user_active_1_day=Aggregation(operation=Operation.LAST),
second_feature=Aggregation(
input_column="active_7_days",
operation=Operation.SUM,
windows=[
Window(n, TimeUnit.DAYS) for n in [3, 5, 9]
]
),
) + [
Aggregation(
input_column=col,
operation=Operation.SUM
) for col in sum_columns # Alternative syntax for defining aggregations.
] + [
Aggregation(
input_column="device",
operation=LAST_K(10)
)
],
dependencies=[
"db_exports.table/ds={{ ds }}" # If not defined will be derived from the Source info.
],
accuracy=Accuracy.SNAPSHOT, # This could be TEMPORAL for point in time correctness.
env={
"backfill": { # Execution environment variables for each of the modes for `run.py`
"EXECUTOR_MEMORY": "4G"
},
},
online=True, # True if this group by needs to be uploaded to a KV Store.
production=False # True if this group by is production level.
)
Join
A Join is a collection of feature values for the keys and (times if applicable) defined on the left (source). Example:
# File <repo>/joins/example_team/example_join.py
from ai.chronon.join import Join, JoinPart
from sources import sample_sources
from group_bys.example_team import example_group_by
v1 = Join(
left=sample_sources.website__views,
right_parts=[
JoinPart(group_by=example_group_by.v0),
],
online=True, # True if this join will be fetched in production.
production=False, # True if this join should not use non-production group bys.
env={"backfill": {"PARALLELISM": "10"}, "streaming": {"STREAMING_ENV_VAR": "VALUE"}},
)
Compile
zipline compile turns authored configs (under group_bys/, joins/, staging_queries/, models/, model_transforms/) into thriftjson under compiled/. The compiler reads team-level defaults (output namespace, env vars, conf, cluster config, and execution info) from teams.py and merges them onto each config's metaData.executionInfo.
zipline compile --chronon-root <repo-root>
Multi-environment compile via teams.canary.py
To compile the same configs against a canary deployment, drop a sibling teams.canary.py next to teams.py. zipline compile will run a second pass and write to compiled_canary/. Only canary is supported as a non-prod env today.
See the Multi-Environment Compile & Deploy guide for the full guide — directory layout, the from teams import … authoring pattern, per-entity environments=[...] opt-in, the --env deploy contract, the compile summary, and the CI workflow.
Pre-commit Setup
- Install pre-commit and other dev libraries:
pip install -r requirements/dev.txt
- Run the following command under
api/pythonto install the git hook scripts:
pre-commit install
To support more pre-commit hooks, add them to the .pre-commit-config.yaml file.
6 maintainers
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