> ## Documentation Index > Fetch the complete documentation index at: https://docs.validio.io/llms.txt > Use this file to discover all available pages before exploring further. # Referential Integrity > The Referential Integrity validator counts primary source records that have no matching record in a reference source. ## Validator overview The **Referential Integrity Validator** ensures record-level consistency between two datasets within a data warehouse. This validator verifies that keys (and optionally values) in your primary source have corresponding matches in a reference source, to help you identify "orphaned" records or data mismatches between related tables. ![The field mapping step of a Referential Integrity validator, pairing source fields with reference fields](https://mintcdn.com/validio/36lh-6_uXUsulPvT/images/docs/validators/750-referential-integrity-mapping.png?fit=max\&auto=format\&n=36lh-6_uXUsulPvT\&q=85\&s=b6039657157612e31909d6850a9681dd) Fields mapping for referential Integrity validator For an overview of all validator types, see [Validator Types](https://docs.validio.io/v10.2/docs/validators/validator-types.md). ## Metric configuration parameters The following parameters are used to configure the Metric calculation for this validator. | Parameters | Description | | :- | :- | | Reference source | Choose the source that contains the dataset you want to compare against the primary source. The source selection is restricted to sources that use the same credential. | | [Window](https://docs.validio.io/v10.2/docs/windows.md) | Select from a list of windows or create a new window to specify how to aggregate the data on the primary source. | | Reference source [window](https://docs.validio.io/v10.2/docs/windows.md) | Select from a list of windows or create a new window to specify how to aggregate the data on the reference source. See [Window Configuration and Constraints](#window-configuration-and-constraints). | | Key fields mapping | Used to join or "match" records between the two sources (for example, `order_ID` to `transaction_ID`). At least one key mapping is required to identify matching records. | | Value fields mapping | (Optional) Once records are matched using key fields, the validator compares the specified value fields to ensure they are identical across both sources. A record whose values differ counts as unmatched. | | Source [filter](https://docs.validio.io/v10.2/docs/filters.md) | (Optional) Select from a list of filters or create a new filter to specify which source records to include (to narrow the scope of the check). | | Reference [filter](https://docs.validio.io/v10.2/docs/filters.md) | (Optional) Select from a list of filters or create a new filter to specify which reference records to include. | | [Segmentation](https://docs.validio.io/v10.2/docs/segmentation.md) | (Optional) Apply segmentation to analyze data in separate groups. Default is `Unsegmented`. | ### Window configuration and constraints The Window determines how data is aggregated before the comparison. To ensure a valid check, the following rules apply: | Primary Source Window | Allowed Reference Source Window | Restriction | | :- | :- | :- | | **Global** | Global | Must match exactly. | | **Tumbling** | Global or Tumbling | If both are Tumbling, they **must be the same size** (for example, both 24-hour windows). | ## Metric calculation The Referential Integrity metric is the **number of unmatched records** in the primary source for each window and segment. It is a count of rows, not a ratio or percentage. A primary source record counts as unmatched when the reference source window has no record with the same values in all key fields and, if configured, all value fields. A key match with differing values counts the same as a missing key. Keep the following in mind when you interpret the metric: * **One direction only.** The validator checks that primary source records exist in the reference source. Records that exist only in the reference source are not counted. * **Every row counts.** If an unmatched key appears in several primary source rows, each row adds to the metric. Duplicate rows in the reference source don't affect the metric. * **Filters narrow the scope.** Primary source records excluded by the source filter are not counted. Windows and segments with no matching records report a metric of `0`. * **Segmentation applies to the primary source.** Reference records are matched on key fields, not on segment. ### Null and empty values | Situation | Result | | :- | :- | | Key field is null in the primary source | Counted as unmatched | | Value field is null in either source (including both) | Counted as unmatched | | Empty string compared with empty string | Match | | Empty string compared with null | Counted as unmatched | Values of different types can match when they look the same, for example the number `1` and the string `'1'`. To exclude records with null keys from the check, add a source filter that uses a [Null filter](https://docs.validio.io/v10.2/docs/filters/filter-types.md#null-filter) with the **Is not null** operator on the key fields. ## Pass condition A record set with full referential integrity has a metric of `0`. Use a [Fixed threshold](https://docs.validio.io/v10.2/docs/thresholds/configuring-fixed-thresholds.md) set to `Equal to` `0` so that any unmatched record creates an incident. To tolerate a known number of orphaned records, set the fixed threshold to `Less than or equal to` that number. New validators default to a Dynamic threshold, which learns the usual number of unmatched records and only alerts on unusual changes. Change it to Fixed if every unmatched record matters. For more information, see [About Thresholds](https://docs.validio.io/v10.2/docs/thresholds.md). ## Debug information When you debug an incident, the debug query lists the unmatched primary source records, and a **Diff type** column shows why each record failed: * `RECORD_MISSING`: no reference record has the same key field values. * `VALUE_MISMATCH`: a reference record has the same key field values, but one or more value fields differ. > [!WARNING] > > Records whose value fields are null in both sources count toward the metric but don't appear in the debug query results. For more information, see [Debugging an Incident](https://docs.validio.io/v10.2/docs/incidents-and-errors/incidents/debugging-an-incident.md).