Make the most important optimizer constants user variables

Variables added:
- optimizer_index_block_copy_cost
- optimizer_key_copy_cost
- optimizer_key_next_find_cost
- optimizer_key_compare_cost
- optimizer_row_copy_cost
- optimizer_where_compare_cost

Some rename of defines was done to make the internal defines similar to
the visible ones:
TIME_FOR_COMPARE -> WHERE_COST; WHERE_COST was also "inverted" to be
a number between 0 and 1 that is multiply with accepted records
(similar to other optimizer variables).
TIME_FOR_COMPARE_IDX -> KEY_COMPARE_COST. This is also inverted,
similar to TIME_FOR_COMPARE.
TIME_FOR_COMPARE_ROWID -> ROWID_COMPARE_COST. This is also inverted,
similar to TIME_FOR_COMPARE.

All default costs are identical to what they where before this patch.

Other things:
- Compare factor in get_merge_buffers_cost() was inverted.
- Changed namespace to static in filesort_utils.cc

1 files changed, 14 insertions, 4 deletions

diff --git a/sql/table.cc b/sql/table.cc
index 17611a1e2fb..16dcb48970d 100644
--- a/sql/table.cc
+++ b/sql/table.cc
@@ -5672,12 +5672,14 @@ void TABLE::init(THD *thd, TABLE_LIST *tl)
   opt_range_condition_rows=0;
   no_cache= false;
   initialize_opt_range_structures();
+
+
   /*
-    Update optimizer_cache_cost to ensure that a SET STATEMENT of
-    the variable it will work.
+    Update optimizer_costs to ensure that a SET STATEMENT of the
+    variables it will work.
   */
-  file->set_optimizer_cache_cost(cache_hit_cost(thd->variables.
-                                                optimizer_cache_hit_ratio));
+  file->set_optimizer_costs(thd);
+
 #ifdef HAVE_REPLICATION
   /* used in RBR Triggers */
   master_had_triggers= 0;
@@ -10434,6 +10436,14 @@ inline void TABLE::initialize_opt_range_structures()
   TRASH_ALLOC(const_key_parts, s->keys * sizeof(*const_key_parts));
 }
 
+
+double TABLE::OPT_RANGE::index_only_fetch_cost(THD *thd)
+{
+  return (index_only_cost + (double) rows *
+          thd->variables.optimizer_key_copy_cost);
+}
+
+
 /*
   Mark table to be reopened after query
 */