shardQuerySplitting: group has pending requests or no shards to run (#108500)

* shardQuerySplitting: group has pending requests or no shards to run

* Comment

* Regression test

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

@@ -6,7 +6,7 @@ import { LokiDatasource } from './datasource';
 import { createLokiDatasource } from './mocks/datasource';
 import { getMockFrames } from './mocks/frames';
 import { runShardSplitQuery } from './shardQuerySplitting';
-import { LokiQuery, LokiQueryDirection } from './types';
+import { LokiQuery, LokiQueryDirection, LokiQueryType } from './types';
 
 jest.mock('uuid', () => ({
   v4: jest.fn().mockReturnValue('uuid'),
@@ -100,6 +100,26 @@ describe('runShardSplitQuery()', () => {
     });
   });
 
+  test('Runs multiple non-sharded queries', async () => {
+    const request = createRequest([
+      { expr: 'count_over_time({a="b"}[$__auto])', refId: 'A' },
+      { expr: 'count_over_time({a="b"}[$__auto])', refId: 'B', queryType: LokiQueryType.Instant },
+    ]);
+    datasource = createLokiDatasource({
+      replace: (input = '') => {
+        return input.replace('$__auto', '5m').replace('$step', '5m');
+      },
+      getVariables: () => [],
+    });
+    jest.spyOn(datasource, 'runQuery').mockReturnValue(of({ data: [] }));
+    datasource.languageProvider.fetchLabelValues = jest.fn();
+    jest.mocked(datasource.languageProvider.fetchLabelValues).mockResolvedValue([]);
+    await expect(runShardSplitQuery(datasource, request)).toEmitValuesWith(() => {
+      // 5 shards, 3 groups + empty shard group, 4 requests
+      expect(datasource.runQuery).toHaveBeenCalledTimes(2);
+    });
+  });
+
   test('Users query splitting for querying over a day', async () => {
     await expect(runShardSplitQuery(datasource, request)).toEmitValuesWith(() => {
       // 5 shards, 3 groups + empty shard group, 4 requests

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

@@ -87,8 +87,9 @@ function splitQueriesByStreamShard(
     }
 
     const nextRequest = () => {
+      // Find the next group to execute, which can be queries with pending shards to execute, or the next query with no shards.
       const nextGroup =
-        groups[group + 1] && groupHasPendingRequests(groups[group + 1])
+        groups[group + 1] && (groups[group + 1].shards === undefined || groupHasPendingRequests(groups[group + 1]))
           ? groups[group + 1]
           : groups.find((shardGroup) => groupHasPendingRequests(shardGroup));