Prometheus: Fix incremental querying logic for public dashboards (#111642)

* also disable incremental querying when the dashboard is public

* add tests for disabling incremental querying if public dashboards are being used

* move public dashboard check earlier

packages/grafana-prometheus/src/datasource.test.ts

@@ -1308,6 +1308,13 @@ describe('PrometheusDatasource incremental query logic', () => {
     expect(mockCache.requestInfo).not.toHaveBeenCalled();
   });
 
+  it('should disable incremental query when public dashboards are being used', async () => {
+    config.publicDashboardAccessToken = 'token';
+    const request = createDataRequest([{ expr: 'rate(up[5m])', refId: 'A' }]);
+    await lastValueFrom(ds.query(request));
+    expect(mockCache.requestInfo).not.toHaveBeenCalled();
+  });
+
   it('should disable incremental query when any target contains $__range', async () => {
     const request = createDataRequest([
       { expr: 'up', refId: 'A' },

packages/grafana-prometheus/src/datasource.ts

@@ -471,7 +471,9 @@ export class PrometheusDatasource
 
     // Use incremental query only if enabled and no instant queries or no $__range variables
     const shouldUseIncrementalQuery =
-      this.hasIncrementalQuery && !request.targets.some((target) => target.instant || target.expr.includes('$__range'));
+      this.hasIncrementalQuery &&
+      !config.publicDashboardAccessToken &&
+      !request.targets.some((target) => target.instant || target.expr?.includes('$__range'));
 
     let fullOrPartialRequest: DataQueryRequest<PromQuery> = request;
     let requestInfo: CacheRequestInfo<PromQuery> | undefined = undefined;