Volumetric Check FAQ¶
Answers to common questions about when the Volumetric check runs, what it compares against, and how AI Managed Volumetric checks behave, grouped by topic.
Behavior¶
Does the check read my data?¶
It does not load your records into Qualytics. It needs only the container's row count, which is why the rule has neither a filter nor a coverage setting. Some platforms provide that count from their table metadata. Otherwise the source runs a COUNT(*) over the container, which on a large view or computed container is real work for the database.
When is the check evaluated?¶
Only when a Scan that includes the Metadata category runs on the container. The daily Observability measurements update the chart but never evaluate the check.
What does Absolute Change compare against?¶
The row count the Scan reads, against the daily count from exactly one Measurement Period earlier. A 7 day check compares with the same weekday last week, not with an average of the week. See Comparisons.
How do I get an alert when a load adds no rows?¶
Create an Absolute Change check with a Measurement Period of 1 and a Min of 1, schedule a Metadata Scan after the load, and route the anomaly with a Flow. See the example.
What is the difference between Volumetric and Freshness?¶
Volumetric answers how much data arrived by reading the row count. Freshness answers when data last arrived by reading the container's last modification time. See Volumetric or Freshness?.
History¶
Why does a new check show as Not Asserted?¶
Change comparisons, and Absolute Value with a period longer than one day, need a daily count for each previous day of the Measurement Period. Until that history exists, the Scan skips the check without an anomaly.
Where do the earlier counts come from?¶
From the container's measurement history: the hourly Observability measurement when Volume Tracking is on (at most one count per day), every Scan that evaluates a Volumetric check, and a successful Profile or a Full Scan that read every record. Days are calendar days in UTC, and when a day has several counts the check uses their average.
Does the Scan's own count become part of the history?¶
Yes, in two ways. Every Scan that evaluates a Volumetric check reads the container's row count and records it, whatever its read strategy. Separately, a successful Full Scan that reads every record, and asserts at least one check, records the number of records it processed. Incremental, continuous, and sampled Scans process part of the container, so that second count is not recorded for them. Both counts join that day's average, so schedule the Scan with care. See The History the Check Needs.
Configuration¶
Can I change the comparison later?¶
Only until a Scan has included the check. After that, create a new check with the new comparison and archive the old one.
Why do Percentage Change limits look different in the API?¶
The app takes them in percent (20 for 20%) and the API in decimals (0.2).
Can I have several Volumetric checks on the same container?¶
Yes, as long as each Active check has its own combination of comparison and Measurement Period. Combining periods is the recommended way to cover both sudden and slow changes, for example a 1 day check for a stalled load and a 28 day check for drift. Two Active checks with the same comparison and period conflict, AI Managed ones included.
AI Managed Checks¶
Which Volumetric checks does Qualytics create automatically?¶
With Create AI Volumetric checks on, up to three per container, all with Absolute Change: a 1 day, a 7 day, and a 28 day check. Each appears once enough history has accumulated for its period.
What happens if I edit an AI Managed check?¶
Changing its comparison, Measurement Period, or limits converts it to Authored, and Qualytics stops updating its limits. Changing only its description, tags, or metadata keeps it AI Managed.