Parent-child hierarchies in DAX rely on this function. For each row it builds one delimited text value listing the IDs of the row's ancestors, top level first and ending with the row's own ID, which PATHITEM, PATHLENGTH and friends can then pick apart.
Read more: Microsoft Learn
In the Ultra Transcenders books
Each book explains PATH in context, with comparison tables and the common traps.
Terms in this definition
- DAX
Short for Data Analysis Expressions, the formula language you write measures, calculated columns and row-level security rules in, within tabular semantic models in Power BI, Excel Power Pivot or Analysis Services.
- Delimited text
Plain text where a chosen separator character divides fields and a terminator closes every row; CSV, TSV and fixed-width files are common forms. Good for structured data that many programs need to read.
- FIRST
A DAX function available only inside visual calculations. It fetches the value at the start of one axis of the visual's matrix, which makes it handy for comparing each point with the first; its opposite is LAST.
- PATHITEM
Reads one entry from a PATH string by position, counted from the left so that 1 is the top of the hierarchy, and gives BLANK when no such position exists. Part of the DAX parent-child family.
- PATHLENGTH
Tells you how many levels a PATH string holds, counting the current item too. Part of the DAX parent-child family.
Related terms
- App Service Health check
An App Service feature that calls a path you choose on each instance every minute, takes persistently failing instances out of load balancing and replaces those still unhealthy after an hour.
- AS-path prepending
Making a BGP route less attractive by repeating ASNs to lengthen its AS path, steering traffic towards a different site or path.
- Azure Application Gateway
A load balancer for web traffic that works at layer 7, sending HTTP and HTTPS requests to back ends based on host name or URL path. It can also handle TLS termination and run a web application firewall, which Azure Load Balancer cannot since it doesn't read web requests.
- Azure Content Moderator
Older moderation service, reached through the /contentmoderator path, that flagged content as a yes/no result and supported custom term lists. It is deprecated, retiring on 15 March 2027, and Azure AI Content Safety replaces it.
- Azure Front Door
Layer-7 global front end that fails over between origins using anycast, terminates TLS, routes requests by URL path and can apply a rate-limiting WAF.
- Azure SQL connection policy
Azure SQL option deciding how clients reach the database: via the gateway with Proxy, or straight to the hosting node with Redirect. It affects the network path only, not who may connect.
- azureml:// URI
Data reference syntax in Azure Machine Learning, written
azureml://datastores/<name>/paths/<path>, that locates data through a datastore already registered in the workspace. - Balanced hierarchy
A hierarchy in which each path has an identical, fixed depth, as with year, quarter, month, date. Ragged hierarchies and parent-child (unbalanced) ones, by contrast, have branches of differing length.