Syntax
------

LOAD INDEX INTO CACHE
 tbl_index_list [, tbl_index_list] ...

tbl_index_list:
 tbl_name
  [[INDEX|KEY] (index_name[, index_name] ...)]
  [IGNORE LEAVES]

Description
-----------

The LOAD INDEX INTO CACHE statement preloads a table index into the key cache
to which it has been assigned by an explicit CACHE INDEX statement, or into
the default key cache otherwise. LOAD INDEX INTO CACHE is used only for MyISAM
or Aria tables.

The IGNORE LEAVES modifier causes only blocks for the nonleaf nodes of the
index to be preloaded.

URL: https://mariadb.com/kb/en/load-index/