diff --git a/core/lib/Drupal/Core/Entity/Query/QueryInterface.php b/core/lib/Drupal/Core/Entity/Query/QueryInterface.php
index c305d0b..b33e9ab 100644
--- a/core/lib/Drupal/Core/Entity/Query/QueryInterface.php
+++ b/core/lib/Drupal/Core/Entity/Query/QueryInterface.php
@@ -15,6 +15,11 @@
 interface QueryInterface extends AlterableInterface {
 
   /**
+   * A property that represents delta used in entity query conditions.
+   */
+  const DELTA = '*delta';
+
+  /**
    * Gets the ID of the entity type for this query.
    *
    * @return string
diff --git a/core/lib/Drupal/Core/Entity/Query/Sql/Tables.php b/core/lib/Drupal/Core/Entity/Query/Sql/Tables.php
index de5aa0b..73712b2 100644
--- a/core/lib/Drupal/Core/Entity/Query/Sql/Tables.php
+++ b/core/lib/Drupal/Core/Entity/Query/Sql/Tables.php
@@ -4,6 +4,7 @@
 
 use Drupal\Core\Database\Query\SelectInterface;
 use Drupal\Core\Entity\Query\QueryException;
+use Drupal\Core\Entity\Query\QueryInterface;
 use Drupal\Core\Entity\Sql\SqlEntityStorageInterface;
 
 /**
@@ -136,7 +137,7 @@ public function addField($field, $type, $langcode) {
               $next = $specifiers[$key + 1];
             }
             else {
-              $column = '_delta';
+              $column = QueryInterface::DELTA;
             }
           }
           // Is this a field column?
diff --git a/core/lib/Drupal/Core/Entity/Sql/DefaultTableMapping.php b/core/lib/Drupal/Core/Entity/Sql/DefaultTableMapping.php
index 170c6ea..607c2c2 100644
--- a/core/lib/Drupal/Core/Entity/Sql/DefaultTableMapping.php
+++ b/core/lib/Drupal/Core/Entity/Sql/DefaultTableMapping.php
@@ -3,6 +3,7 @@
 namespace Drupal\Core\Entity\Sql;
 
 use Drupal\Core\Entity\ContentEntityTypeInterface;
+use Drupal\Core\Entity\Query\QueryInterface;
 use Drupal\Core\Field\FieldStorageDefinitionInterface;
 
 /**
@@ -203,7 +204,7 @@ public function getFieldColumnName(FieldStorageDefinitionInterface $storage_defi
       $column_name = count($storage_definition->getColumns()) == 1 ? $field_name :  $field_name . '__' . $property_name;
     }
     elseif ($this->requiresDedicatedTableStorage($storage_definition)) {
-      if ($property_name == '_delta') {
+      if ($property_name == QueryInterface::DELTA) {
         $column_name = 'delta';
       }
       else {