Graph Match operator error when project is not specified

Question

I'm going through examples here: https://learn.microsoft.com/en-us/azure/data-explorer/kusto/query/graph-match-operator

I'm attempting to use an anonymous node and edge combinations to get all matching nodes with the pattern

()--[]--()

which to my understanding is valid.

I'm using the example here: https://dataexplorer.azure.com/clusters/help/databases/Samples

with the query

 
let employees = datatable(name:string, age:long) 
[ 
 "Alice", 32,  
 "Bob", 31,  
 "Eve", 27,  
 "Joe", 29,  
 "Chris", 45, 
 "Alex", 35,
 "Ben", 23,
 "Richard", 39,
]; 
let reports = datatable(employee:string, manager:string) 
[ 
 "Bob", "Alice",  
 "Chris", "Alice",  
 "Eve", "Bob",
 "Ben", "Chris",
 "Joe", "Alice", 
 "Richard", "Bob"
]; 
reports 
| make-graph employee --> manager with employees on name 
| graph-match ()<-[]-()

From the documents, it seems like the projection should be optional but the query fails with

Semantic Error graph-match operator: missing project clause

Is there an example of how to use anonymous nodes and variables to match all entries that match the pattern?

Answer 1

Hi @Waruna Yapa ,

Thanks for using Microsoft Q&A platform .

I see, the error is likely occurring because the query doesn't specify what should be projected after the graph-match operation. To avoid the "missing project clause" error, you need to include a projection statement after the graph-match operation.

Could you please specify where it's mentioned that projection is optional in the document you shared.

Kindly try the below code , this query should match all entries that match the pattern ()--[]--().

let employees = datatable(name:string, age:long) 
[ 
 "Alice", 32,  
 "Bob", 31,  
 "Eve", 27,  
 "Joe", 29,  
 "Chris", 45, 
 "Alex", 35,
 "Ben", 23,
 "Richard", 39,
]; 
let reports = datatable(employee:string, manager:string) 
[ 
 "Bob", "Alice",  
 "Chris", "Alice",  
 "Eve", "Bob",
 "Ben", "Chris",
 "Joe", "Alice", 
 "Richard", "Bob"
]; 
reports 
| make-graph employee --> manager with employees on name 
| graph-match (A)<-[]-(B)
  project manager=A.name , emp=B.name

Hope it helps. Kindly accept the answer by clicking on `Accept answer button. Thankyou