reverted:
--- b/core/lib/Drupal/Core/Database/Connection.php
+++ a/core/lib/Drupal/Core/Database/Connection.php
@@ -490,45 +490,6 @@
     return $this->prefixTables('{' . $table . '}_' . $field . '_seq');
   }
 
-  /**
-   * Retrieves a sequence owned by a table and column.
-   *
-   * @param string $table
-   *   A table name that is not prefixed or quoted.
-   * @param string $column
-   *   The column name.
-   *
-   * @return string|null
-   *   The name of the sequence or NULL if it does not exist.
-   */
-  public function getSequence($table, $column) {
-    $args = [
-      ':table' => $this->prefixTables('{' . $table . '}'),
-      ':column' => $column,
-    ];
-    return $this
-      ->query("SELECT pg_get_serial_sequence(:table, :column)", $args)
-      ->fetchField();
-  }
-
-  /**
-   * Checks if a sequence exists at all.
-   *
-   * @param string $name
-   *   The fully-qualified sequence name.
-   *
-   * @return bool
-   *   TRUE if the sequence exists by the name.
-   *
-   * @see \Drupal\Core\Database\Connection::makeSequenceName()
-   */
-  public function sequenceExists($name) {
-    $args = [':name' => $name];
-    return (bool) $this
-      ->query("SELECT c.relname FROM pg_class as c INNER JOIN pg_namespace as ns ON (c.relnamespace = ns.oid) WHERE c.relkind = 'S' AND c.relname = :name", $args)
-      ->fetchField();
-  }
-
   /**
    * Flatten an array of query comments into a single comment string.
    *
only in patch2:
unchanged:
--- a/core/lib/Drupal/Core/Database/Driver/pgsql/Connection.php
+++ b/core/lib/Drupal/Core/Database/Driver/pgsql/Connection.php
@@ -454,6 +454,45 @@ public function upsert($table, array $options = []) {
     return new $class($this, $table, $options);
   }
 
+  /**
+   * Retrieves a sequence owned by a table and column.
+   *
+   * @param string $table
+   *   A table name that is not prefixed or quoted.
+   * @param string $column
+   *   The column name.
+   *
+   * @return string|null
+   *   The name of the sequence or NULL if it does not exist.
+   */
+  public function getSequence($table, $column) {
+    $args = [
+      ':table' => $this->prefixTables('{' . $table . '}'),
+      ':column' => $column,
+    ];
+    return $this
+      ->query("SELECT pg_get_serial_sequence(:table, :column)", $args)
+      ->fetchField();
+  }
+
+  /**
+   * Checks if a sequence exists at all.
+   *
+   * @param string $name
+   *   The fully-qualified sequence name.
+   *
+   * @return bool
+   *   TRUE if the sequence exists by the name.
+   *
+   * @see \Drupal\Core\Database\Connection::makeSequenceName()
+   */
+  public function sequenceExists($name) {
+    $args = [':name' => $name];
+    return (bool) $this
+      ->query("SELECT c.relname FROM pg_class as c INNER JOIN pg_namespace as ns ON (c.relnamespace = ns.oid) WHERE c.relkind = 'S' AND c.relname = :name", $args)
+      ->fetchField();
+  }
+
 }
 
 /**