Commit e35244d6 authored by unknown's avatar unknown
Browse files

Add a comment to update_ref_and_keys

parent 9b583225

sql/sql_select.cc

+7 −3
Original line number Diff line number Diff line
@@ -3161,10 +3161,14 @@ update_ref_and_keys(THD *thd, DYNAMIC_ARRAY *keyuse,JOIN_TAB *join_tab, 
  }



  /*

    Special treatment for ft-keys.

    Remove the following things from KEYUSE:

    Sort the array of possible keys and remove the following key parts:

    - ref if there is a keypart which is a ref and a const.

    - keyparts without previous keyparts.

      (e.g. if there is a key(a,b) and the clause is a=3 and b=7 and b=t2.d,

      then we skip the key part corresponding to b=t2.d)

    - keyparts without previous keyparts

      (e.g. if there is a key(a,b,c) but only b < 5 (or a=2 and c < 3) is

      used in the query, we drop the partial key parts from consideration).

    Special treatment for ft-keys.

  */

  if (keyuse->elements)

  {