Issue #3015691 by hchonov, mondrake: entityQueryAggregate queries cannot be executed more than once

core/lib/Drupal/Core/Entity/Query/Sql/Query.php

@@ -21,6 +21,13 @@ class Query extends QueryBase implements QueryInterface {
    */
   protected $sqlQuery;
 
+  /**
+   * The Tables object for this query.
+   *
+   * @var \Drupal\Core\Entity\Query\Sql\TablesInterface
+   */
+  protected $tables;
+
   /**
    * An array of fields keyed by the field alias.
    *
@@ -101,6 +108,9 @@ protected function prepare() {
       $simple_query = FALSE;
     }
     $this->sqlQuery = $this->connection->select($base_table, 'base_table', ['conjunction' => $this->conjunction]);
+    // Reset the tables structure, as it might have been built for a previous
+    // execution of this query.
+    $this->tables = NULL;
     $this->sqlQuery->addMetaData('entity_type', $this->entityTypeId);
     $id_field = $this->entityType->getKey('id');
     // Add the key field for fetchAllKeyed().

core/tests/Drupal/KernelTests/Core/Entity/EntityQueryAggregateTest.php

@@ -541,6 +541,38 @@ public function testAggregation() {
 
   }
 
+  /**
+   * Tests preparing a query and executing twice.
+   */
+  public function testRepeatedExecution() {
+    $query = $this->entityStorage->getAggregateQuery()
+      ->groupBy('user_id');
+
+    $this->queryResult = $query->execute();
+    $this->assertResults([
+      ['user_id' => 1],
+      ['user_id' => 2],
+      ['user_id' => 3],
+    ]);
+
+    $entity = $this->entityStorage->create([
+      'id' => 7,
+      'user_id' => 4,
+      'field_test_1' => 42,
+      'field_test_2' => 68,
+    ]);
+    $entity->enforceIsNew();
+    $entity->save();
+
+    $this->queryResult = $query->execute();
+    $this->assertResults([
+      ['user_id' => 1],
+      ['user_id' => 2],
+      ['user_id' => 3],
+      ['user_id' => 4],
+    ]);
+  }
+
   /**
    * Asserts the results as expected regardless of order between and in rows.
    *