Revert "Loki: do not produce histogram for instant queries (#50019) (#50065)" (#50181)

This reverts commit 063c5095eb.

public/app/plugins/datasource/loki/datasource.test.ts

@@ -25,7 +25,7 @@ import { CustomVariableModel } from '../../../features/variables/types';
 
 import { isMetricsQuery, LokiDatasource, RangeQueryOptions } from './datasource';
 import { makeMockLokiDatasource } from './mocks';
-import { LokiQuery, LokiQueryType, LokiResponse, LokiResultType } from './types';
+import { LokiQuery, LokiResponse, LokiResultType } from './types';
 
 jest.mock('@grafana/runtime', () => ({
   // @ts-ignore
@@ -997,15 +997,6 @@ describe('LokiDatasource', () => {
 
       expect(ds.getLogsVolumeDataProvider(options)).toBeDefined();
     });
-
-    it('does not create provider if there is only an instant logs query', () => {
-      const ds = createLokiDSForTests();
-      const options = getQueryOptions<LokiQuery>({
-        targets: [{ expr: '{label=value', refId: 'A', queryType: LokiQueryType.Instant }],
-      });
-
-      expect(ds.getLogsVolumeDataProvider(options)).not.toBeDefined();
-    });
   });
 
   describe('importing queries', () => {

public/app/plugins/datasource/loki/datasource.ts

@@ -141,28 +141,22 @@ export class LokiDatasource
   }
 
   getLogsVolumeDataProvider(request: DataQueryRequest<LokiQuery>): Observable<DataQueryResponse> | undefined {
-    const isQuerySuitable = (query: LokiQuery) => {
-      const normalized = getNormalizedLokiQuery(query);
-      const { expr } = normalized;
-      // it has to be a logs-producing range-query
-      return expr && !isMetricsQuery(expr) && normalized.queryType === LokiQueryType.Range;
-    };
-
-    const isLogsVolumeAvailable = request.targets.some(isQuerySuitable);
-
+    const isLogsVolumeAvailable = request.targets.some((target) => target.expr && !isMetricsQuery(target.expr));
     if (!isLogsVolumeAvailable) {
       return undefined;
     }
 
     const logsVolumeRequest = cloneDeep(request);
-    logsVolumeRequest.targets = logsVolumeRequest.targets.filter(isQuerySuitable).map((target) => {
-      return {
-        ...target,
-        instant: false,
-        volumeQuery: true,
-        expr: `sum by (level) (count_over_time(${target.expr}[$__interval]))`,
-      };
-    });
+    logsVolumeRequest.targets = logsVolumeRequest.targets
+      .filter((target) => target.expr && !isMetricsQuery(target.expr))
+      .map((target) => {
+        return {
+          ...target,
+          instant: false,
+          volumeQuery: true,
+          expr: `sum by (level) (count_over_time(${target.expr}[$__interval]))`,
+        };
+      });
 
     return queryLogsVolume(this, logsVolumeRequest, {
       extractLevel,