Cron Triggers

A scheduled trigger runs a Function at fixed times, whether or not any upstream data has changed. Publishers, Transformers, and Subscribers can all use one.

Configure it by passing a CronTrigger to trigger_by.

from tabsdatak.api import CronTrigger, publisher, TableFrameSpec
from tabsdatak.conn.mysql import MySQLSrc


@publisher(
    trigger_by=CronTrigger("0 * * * *"),
    source=MySQLSrc(queries=["SELECT * FROM sales"]),
    output_tables=["sales"],
)
def read_sales(sales: TableFrameSpec) -> TableFrameSpec:
    return sales

The mask

The first argument is a standard Unix crontab mask with five fields and minute precision:

Minute Hour Day Month Day-of-Week

Mask	Runs
0,30 * * * *	every 30 minutes, on the hour and at minute 30
0 0 * * *	daily at 00:00
0 22 * * FRI	Fridays at 22:00

Non-standard shorthands such as @hourly and @daily are not supported.

note

All crontab schedules are interpreted in UTC.

Limiting the window

CronTrigger also takes optional start and end parameters, each either a timezone-aware Python datetime or an ISO 8601 string in UTC (2026-01-01T12:00:00Z).

With them set, the mask only fires between those two times. With them omitted, it fires indefinitely from the moment the Function is registered.

Enabled and disabled Functions

A cron schedule only runs while its Function is enabled. Registration defaults to enabled, and tdk fn register takes --enabled / --disabled explicitly. An already-registered Function is toggled with tdk fn enable and tdk fn disable.

A disabled Function ignores its mask entirely. It does not queue missed runs and fire them on re-enable.

Where credentials come from

The example above names a MySQL query but carries no host and no password. Those live on the Collection's Connection. See Connections.