Merge branch '5.5' into 10.0

1 files changed, 16 insertions, 2 deletions

diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 2aeddf2415d..e0f560f0b3a 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -9736,10 +9736,24 @@ make_join_select(JOIN *join,SQL_SELECT *select,COND *cond)
 	  if (!sel->quick_keys.is_subset(tab->checked_keys) ||
               !sel->needed_reg.is_subset(tab->checked_keys))
 	  {
+            /*
+              "Range checked for each record" is a "last resort" access method
+              that should only be used when the other option is a cross-product
+              join.
+
+              We use the following condition (it's approximate):
+              1. There are potential keys for (sel->needed_reg)
+              2. There were no possible ways to construct a quick select, or
+                 the quick select would be more expensive than the full table
+                 scan.
+            */
 	    tab->use_quick= (!sel->needed_reg.is_clear_all() &&
 			     (sel->quick_keys.is_clear_all() ||
-			      (sel->quick &&
-			       (sel->quick->records >= 100L)))) ?
+                              (sel->quick && 
+                               sel->quick->read_time > 
+                               tab->table->file->scan_time() + 
+                               tab->table->file->stats.records/TIME_FOR_COMPARE
+                               ))) ?
 	      2 : 1;
 	    sel->read_tables= used_tables & ~current_map;
             sel->quick_keys.clear_all();