Bug #43029: FORCE INDEX FOR ORDER BY is ignored when join

buffering is used

FORCE INDEX FOR ORDER BY now prevents the optimizer from 
using join buffering. As a result the optimizer can use
indexed access on the first table and doesn't need to 
sort the complete resultset at the end of the statement.

1 files changed, 4 insertions, 2 deletions

diff --git a/sql/sql_base.cc b/sql/sql_base.cc
index d1e96fcdbb3..e706bd04ea6 100644
--- a/sql/sql_base.cc
+++ b/sql/sql_base.cc
@@ -2305,7 +2305,8 @@ bool reopen_name_locked_table(THD* thd, TABLE_LIST* table_list, bool link_in)
   table->tablenr=thd->current_tablenr++;
   table->used_fields=0;
   table->const_table=0;
-  table->null_row= table->maybe_null= table->force_index= 0;
+  table->null_row= table->maybe_null= 0;
+  table->force_index= table->force_index_order= table->force_index_group= 0;
   table->status=STATUS_NO_RECORD;
   DBUG_RETURN(FALSE);
 }
@@ -2963,7 +2964,8 @@ TABLE *open_table(THD *thd, TABLE_LIST *table_list, MEM_ROOT *mem_root,
   table->tablenr=thd->current_tablenr++;
   table->used_fields=0;
   table->const_table=0;
-  table->null_row= table->maybe_null= table->force_index= 0;
+  table->null_row= table->maybe_null= 0;
+  table->force_index= table->force_index_order= table->force_index_group= 0;
   table->status=STATUS_NO_RECORD;
   table->insert_values= 0;
   table->fulltext_searched= 0;