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Missing or null link_ids in the RDF UK Midpoint table

Summary
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Some records in the RDF POSTAL_CODE_MIDPOINT table may contain missing or null link_id values. This occurs when a postal code cannot be reliably associated with a road segment in the map data. The postal code location remains usable via its latitude and longitude coordinates.



Applies To
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HERE RDF (Classic RDF and Unified RDF)
 POSTAL_CODE_MIDPOINT dataset



Answer
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A missing or null link_id in the POSTAL_CODE_MIDPOINT table indicates that the postal code could not be reliably linked to a road segment during data compilation.

This can happen due to changes in the road network, temporary inconsistencies between datasets, or data quality limitations. Even when a link_id is not available, the postal code record is still provided with geographic coordinates, allowing it to be used for mapping, geocoding, and spatial analysis.

Customers should not assume that all postal codes will have a valid link_id and should implement fallback logic using latitude and longitude where necessary.



Symptoms
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Customers may observe one or more of the following:

Null or empty link_id values in POSTAL_CODE_MIDPOINT
 Postal codes without associated road links
Valid geographic coordinates but missing network linkage
 Inconsistent or unexpected link associations



Root Cause
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### 1. Road Network Changes

Road links in the map data are continuously updated. Changes such as splitting, merging, or deletion of road segments may result in previously valid link_id values no longer being available.

### 2. Data Synchronization Gaps

Postal code data and road network data are compiled from different sources and processes. Their update cycles may not always align perfectly, which can lead to temporary inconsistencies.

### 3. Data Quality Limitations

In some cases, postal code locations cannot be confidently matched to a specific road segment due to ambiguity or incomplete source data.

### 4. Data Retention Design

Postal code records are retained even when a link association cannot be established. This ensures that valid geographic locations are not excluded from the dataset.



Impact
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| Scenario | Impact |
| --- | --- |
| link_id is present | Postal code can be used for network-based operations (e.g., routing, map matching) |
| link_id is null | Postal code can still be used via latitude/longitude but not for link-based operations |



Recommended Actions
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### 1. Use Coordinates as Fallback

For records with null link_id, use the available latitude and longitude for:

Map visualization
 Spatial analysis
Geocoding or reverse geocoding

### 2. Avoid Strict Dependency on link_id

Applications should not rely exclusively on link_id for postal code processing, as not all records will contain valid link associations.

### 3. Validate Link Associations (Optional)

If link-based accuracy is critical, validate whether the link_id exists in the road network dataset.

Example SQL query:

<br />SELECT pcm.postal_code, pcm.link_idFROM POSTAL_CODE_MIDPOINT pcmLEFT JOIN ROAD_LINK rlON pcm.link_id = rl.link_idWHERE pcm.link_id IS NOT NULLAND rl.link_id IS NULL;<br />

This query helps identify postal codes referencing invalid or outdated link identifiers.



### 4. Contact HERE Support

If you observe any of the following, contact HERE Support:

 A large number of missing link_id values
Geographic inconsistencies (e.g., incorrect country linkage)
 Sudden changes between dataset releases

Provide:

RDF version
 Region
Example records



Expected Behavior
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| Situation | Expected |
| --- | --- |
| Small number of missing link_id values | Yes |
| Temporary inconsistencies between releases | Yes |
| Large-scale or systematic issues | No (should be reported) |



Notes
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 RDF datasets are designed to provide a consistent and comprehensive representation of map data.
Due to the complexity of real-world geography and data integration, not all entities can always be perfectly linked.
 Postal code midpoint records remain valid and usable even when link associations are unavailable.



Related Information
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The following public resources provide additional context:

HERE Platform Documentation – https://docs.here.com
 HERE Data Specifications (RDF overview) – https://docs.here.com/map-content
* HERE Support Portal – https://support.here.com



Keywords
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RDF, POSTAL_CODE_MIDPOINT, link_id, null values, postal code midpoint, road link, data consistency, geospatial data, HERE platform