Prometheus: Show only graph for range queries in Explore (#32489)

* Remove showing of table for range query

* Improve comment

public/app/plugins/datasource/prometheus/datasource.ts

@@ -284,7 +284,6 @@ export class PrometheusDatasource extends DataSourceApi<PromQuery, PromOptions>
 
   private exploreQuery(queries: PromQueryRequest[], activeTargets: PromQuery[], end: number) {
     let runningQueriesCount = queries.length;
-    const mixedQueries = activeTargets.some((t) => t.range) && activeTargets.some((t) => t.instant);
 
     const subQueries = queries.map((query, index) => {
       const target = activeTargets[index];
@@ -299,7 +298,6 @@ export class PrometheusDatasource extends DataSourceApi<PromQuery, PromOptions>
             query,
             target,
             responseListLength: queries.length,
-            mixedQueries,
             exemplarTraceIdDestinations: this.exemplarTraceIdDestinations,
           });
           return {

public/app/plugins/datasource/prometheus/result_transformer.ts

@@ -45,7 +45,6 @@ export function transform(
     target: PromQuery;
     responseListLength: number;
     scopedVars?: ScopedVars;
-    mixedQueries?: boolean;
   }
 ) {
   // Create options object from transformOptions
@@ -61,14 +60,8 @@ export function transform(
     refId: transformOptions.target.refId,
     valueWithRefId: transformOptions.target.valueWithRefId,
     meta: {
-      /**
-       * Fix for showing of Prometheus results in Explore table.
-       * We want to show result of instant query always in table and result of range query based on target.runAll;
-       */
-      preferredVisualisationType: getPreferredVisualisationType(
-        transformOptions.query.instant,
-        transformOptions.mixedQueries
-      ),
+      // Fix for showing of Prometheus results in Explore table
+      preferredVisualisationType: transformOptions.query.instant ? 'table' : 'graph',
     },
   };
   const prometheusResult = response.data.data;
@@ -228,14 +221,6 @@ function sampleExemplars(events: TimeAndValue[], options: TransformOptions) {
   return sampledExemplars;
 }
 
-function getPreferredVisualisationType(isInstantQuery?: boolean, mixedQueries?: boolean) {
-  if (isInstantQuery) {
-    return 'table';
-  }
-
-  return mixedQueries ? 'graph' : undefined;
-}
-
 /**
  * Transforms matrix and vector result from Prometheus result to DataFrame
  */