checking-freshness▌
astronomer/agents · updated Apr 8, 2026
Verify data freshness by checking table timestamps and update patterns against a staleness scale.
- ›Identifies timestamp columns using common ETL naming patterns ( _loaded_at , _updated_at , created_at , etc.) and queries their maximum values to determine age
- ›Classifies data into four freshness statuses: Fresh (< 4 hours), Stale (4–24 hours), Very Stale (> 24 hours), or Unknown (no timestamp found)
- ›Provides SQL templates for checking last update time and row count trends over rece
Data Freshness Check
Quickly determine if data is fresh enough to use.
Freshness Check Process
For each table to check:
1. Find the Timestamp Column
Look for columns that indicate when data was loaded or updated:
_loaded_at,_updated_at,_created_at(common ETL patterns)updated_at,created_at,modified_at(application timestamps)load_date,etl_timestamp,ingestion_timedate,event_date,transaction_date(business dates)
Query INFORMATION_SCHEMA.COLUMNS if you need to see column names.
2. Query Last Update Time
SELECT
MAX(<timestamp_column>) as last_update,
CURRENT_TIMESTAMP() as current_time,
TIMESTAMPDIFF('hour', MAX(<timestamp_column>), CURRENT_TIMESTAMP()) as hours_ago,
TIMESTAMPDIFF('minute', MAX(<timestamp_column>), CURRENT_TIMESTAMP()) as minutes_ago
FROM <table>
3. Check Row Counts by Time
For tables with regular updates, check recent activity:
SELECT
DATE_TRUNC('day', <timestamp_column>) as day,
COUNT(*) as row_count
FROM <table>
WHERE <timestamp_column> >= DATEADD('day', -7, CURRENT_DATE())
GROUP BY 1
ORDER BY 1 DESC
Freshness Status
Report status using this scale:
| Status | Age | Meaning |
|---|---|---|
| Fresh | < 4 hours | Data is current |
| Stale | 4-24 hours | May be outdated, check if expected |
| Very Stale | > 24 hours | Likely a problem unless batch job |
| Unknown | No timestamp | Can't determine freshness |
If Data is Stale
Check Airflow for the source pipeline:
-
Find the DAG: Which DAG populates this table? Use
af dags listand look for matching names. -
Check DAG status:
- Is the DAG paused? Use
af dags get <dag_id> - Did the last run fail? Use
af dags stats - Is a run currently in progress?
- Is the DAG paused? Use
-
Diagnose if needed: If the DAG failed, use the debugging-dags skill to investigate.
On Astro
If you're running on Astro, you can also:
- DAG history in the Astro UI: Check the deployment's DAG run history for a visual timeline of recent runs and their outcomes
- Astro alerts for SLA monitoring: Configure alerts to get notified when DAGs miss their expected completion windows, catching staleness before users report it
On OSS Airflow
- Airflow UI: Use the DAGs view and task logs to verify last successful runs and SLA misses
Output Format
Provide a clear, scannable report:
FRESHNESS REPORT
================
TABLE: database.schema.table_name
Last Update: 2024-01-15 14:32:00 UTC
Age: 2 hours 15 minutes
Status: Fresh
TABLE: database.schema.other_table
Last Update: 2024-01-14 03:00:00 UTC
Age: 37 hours
Status: Very Stale
Source DAG: daily_etl_pipeline (FAILED)
Action: Investigate with **debugging-dags** skill
Quick Checks
If user just wants a yes/no answer:
- "Is X fresh?" -> Check and respond with status + one line
- "Can I use X for my 9am meeting?" -> Check and give clear yes/no with context