Change optimizer_use_mrr=auto|disable|force

to be optimizer_switch flags mrr=on|off and mrr_cost_based=on|off.

mysql-test/r/innodb_mrr.result

@@ -665,8 +665,8 @@ set join_buffer_size=@my_save_join_buffer_size;
 #
 create table t1 (pk int primary key, b int, c int default 0, index idx(b)) engine=innodb;
 insert into t1(pk,b) values (3, 30), (2, 20), (9, 90), (7, 70), (4, 40), (5, 50), (10, 100), (12, 120);
-set @my_save_optimizer_use_mrr=@@optimizer_use_mrr;
-set optimizer_use_mrr='disable';
+set @bug665669_tmp=@@optimizer_switch;
+set optimizer_switch='mrr=off';
 explain select * from t1 where b > 1000;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	range	idx	idx	5	NULL	1	Using index condition
@@ -680,7 +680,7 @@ pk	b	c
 3	30	0
 4	40	0
 drop table t1;
-set optimizer_use_mrr = @my_save_optimizer_use_mrr;
+set optimizer_switch = @bug665669_tmp;
 #
 # Bug#43360 - Server crash with a simple multi-table update
 #

mysql-test/r/maria_mrr.result

@@ -370,7 +370,6 @@ DROP TABLE t1,t2,t3;
 # BUG#671361: virtual int Mrr_ordered_index_reader::refill_buffer(): Assertion `!know_key_tuple_params
 # (works only on Maria because we need 1024-byte long key)
 #
-SET SESSION optimizer_use_mrr = 'force';
 SET SESSION join_cache_level = 6;
 SET SESSION join_buffer_size = 1024;
 CREATE TABLE t1 (

mysql-test/r/subselect4.result

@@ -259,17 +259,14 @@ KEY `varchar_key` (`varchar_key`)
 ) AUTO_INCREMENT=12 DEFAULT CHARSET=latin1;
 INSERT INTO `t1` VALUES (10,'00:00:00','i','i'),(11,'00:00:00','','');
 set @old_optimizer_switch          = @@session.optimizer_switch,
-@old_optimizer_use_mrr         = @@session.optimizer_use_mrr,
 @old_engine_condition_pushdown = @@session.engine_condition_pushdown;
-SET SESSION OPTIMIZER_SWITCH = 'materialization=off,semijoin=off,loosescan=off,firstmatch=off';
-SET SESSION optimizer_use_mrr = 'force';
+SET SESSION OPTIMIZER_SWITCH = 'materialization=off,semijoin=off,loosescan=off,firstmatch=off,mrr=on';
 SET SESSION engine_condition_pushdown = 1;
 SELECT `time_nokey` G1  FROM t1  WHERE ( `varchar_nokey`  , `varchar_key`  )  IN ( 
 SELECT `varchar_nokey`  , `varchar_nokey`  )  AND `varchar_key`  >= 'c' HAVING G1  ORDER 
 BY `pk`   ;
 G1
 set @@session.optimizer_switch          = @old_optimizer_switch,
-@@session.optimizer_use_mrr         = @old_optimizer_use_mrr,
 @@session.engine_condition_pushdown = @old_engine_condition_pushdown;
 DROP TABLE t1;
 #

mysql-test/suite/optimizer_unfixed_bugs/r/bug41996-extra1.result

-set optimizer_use_mrr='disable';
+set @bug41996_tmp=@@optimizer_switch;
+set optimizer_switch='mrr=off';
 DROP DATABASE IF EXISTS d1;
 DROP DATABASE IF EXISTS d2;
 DROP DATABASE IF EXISTS d3;
@@ -1106,3 +1107,4 @@ c1	c2
 DROP DATABASE d1;
 DROP DATABASE d2;
 DROP DATABASE d3;
+set optimizer_switch=@bug41996_tmp;

mysql-test/suite/optimizer_unfixed_bugs/t/bug41996-extra1.test

-set optimizer_use_mrr='disable';
+set @bug41996_tmp=@@optimizer_switch;
+set optimizer_switch='mrr=off';
 --disable_warnings
 DROP DATABASE IF EXISTS d1;
 DROP DATABASE IF EXISTS d2;
@@ -484,4 +485,4 @@ SELECT * FROM d3.t3 ORDER BY c1;
 DROP DATABASE d1;
 DROP DATABASE d2;
 DROP DATABASE d3;
-
+set optimizer_switch=@bug41996_tmp;

mysql-test/t/innodb_mrr.test

@@ -370,14 +370,14 @@ set join_buffer_size=@my_save_join_buffer_size;
 --echo #
 create table t1 (pk int primary key, b int, c int default 0, index idx(b)) engine=innodb;
 insert into t1(pk,b) values (3, 30), (2, 20), (9, 90), (7, 70), (4, 40), (5, 50), (10, 100), (12, 120);
-set @my_save_optimizer_use_mrr=@@optimizer_use_mrr;
-set optimizer_use_mrr='disable';
+set @bug665669_tmp=@@optimizer_switch;
+set optimizer_switch='mrr=off';
 explain select * from t1 where b > 1000;
 --echo # The following two must produce indentical results:
 select * from t1 where pk < 2 or pk between 3 and 4;
 select * from t1 where pk < 2 or pk between 3 and 4;   
 drop table t1;
-set optimizer_use_mrr = @my_save_optimizer_use_mrr;
+set optimizer_switch = @bug665669_tmp;
 --echo #
 --echo # Bug#43360 - Server crash with a simple multi-table update
 --echo #

mysql-test/t/maria_mrr.test

@@ -92,7 +92,6 @@ DROP TABLE t1,t2,t3;
 --echo # (works only on Maria because we need 1024-byte long key)
 --echo #
 
-SET SESSION optimizer_use_mrr = 'force';
 SET SESSION join_cache_level = 6;
 SET SESSION join_buffer_size = 1024;
 CREATE TABLE t1 (

mysql-test/t/subselect4.test

@@ -219,11 +219,9 @@ CREATE TABLE `t1` (
 INSERT INTO `t1` VALUES (10,'00:00:00','i','i'),(11,'00:00:00','','');
 
 set @old_optimizer_switch          = @@session.optimizer_switch,
-    @old_optimizer_use_mrr         = @@session.optimizer_use_mrr,
     @old_engine_condition_pushdown = @@session.engine_condition_pushdown;
 
-SET SESSION OPTIMIZER_SWITCH = 'materialization=off,semijoin=off,loosescan=off,firstmatch=off';
-SET SESSION optimizer_use_mrr = 'force';
+SET SESSION OPTIMIZER_SWITCH = 'materialization=off,semijoin=off,loosescan=off,firstmatch=off,mrr=on';
 SET SESSION engine_condition_pushdown = 1;
 
  SELECT `time_nokey` G1  FROM t1  WHERE ( `varchar_nokey`  , `varchar_key`  )  IN ( 
@@ -231,7 +229,6 @@ SELECT `varchar_nokey`  , `varchar_nokey`  )  AND `varchar_key`  >= 'c' HAVING G
 BY `pk`   ;
 
 set @@session.optimizer_switch          = @old_optimizer_switch,
-    @@session.optimizer_use_mrr         = @old_optimizer_use_mrr,
     @@session.engine_condition_pushdown = @old_engine_condition_pushdown;
 
 DROP TABLE t1;

sql/multi_range_read.cc

@@ -1416,7 +1416,7 @@ ha_rows DsMrr_impl::dsmrr_info_const(uint keyno, RANGE_SEQ_IF *seq,
   /*
     If HA_MRR_USE_DEFAULT_IMPL has been passed to us, that is an order to
     use the default MRR implementation (we need it for UPDATE/DELETE).
-    Otherwise, make a choice based on cost and @@optimizer_use_mrr.
+    Otherwise, make a choice based on cost and @@optimizer_switch settings
   */
   if ((*flags & HA_MRR_USE_DEFAULT_IMPL) ||
       choose_mrr_impl(keyno, rows, flags, bufsz, cost))
@@ -1520,7 +1520,8 @@ bool DsMrr_impl::choose_mrr_impl(uint keyno, ha_rows rows, uint *flags,
   bool using_cpk= test(keyno == table->s->primary_key &&
                        primary_file->primary_key_is_clustered());
   *flags &= ~HA_MRR_IMPLEMENTATION_FLAGS;
-  if (thd->variables.optimizer_use_mrr == 2 || *flags & HA_MRR_INDEX_ONLY ||
+  if (!optimizer_flag(thd, OPTIMIZER_SWITCH_MRR) ||
+      *flags & HA_MRR_INDEX_ONLY ||
       (using_cpk && !doing_cpk_scan) || key_uses_partial_cols(table, keyno))
   {
     /* Use the default implementation */
@@ -1537,12 +1538,12 @@ bool DsMrr_impl::choose_mrr_impl(uint keyno, ha_rows rows, uint *flags,
   
   bool force_dsmrr;
   /* 
-    If @@optimizer_use_mrr==force, then set cost of DS-MRR to be minimum of
+    If mrr_cost_based flag is not set, then set cost of DS-MRR to be minimum of
     DS-MRR and Default implementations cost. This allows one to force use of
     DS-MRR whenever it is applicable without affecting other cost-based
     choices.
   */
-  if ((force_dsmrr= (thd->variables.optimizer_use_mrr == 1)) &&
+  if ((force_dsmrr= !optimizer_flag(thd, OPTIMIZER_SWITCH_MRR_COST_BASED)) &&
       dsmrr_cost.total_cost() > cost->total_cost())
     dsmrr_cost= *cost;
 

sql/mysql_priv.h

@@ -575,18 +575,27 @@ protected:
 #define OPTIMIZER_SWITCH_PARTIAL_MATCH_ROWID_MERGE  (1<<11)
 #define OPTIMIZER_SWITCH_PARTIAL_MATCH_TABLE_SCAN (1<<12)
 #define OPTIMIZER_SWITCH_SUBQUERY_CACHE (1<<13)
-#define OPTIMIZER_SWITCH_MRR_SORT_KEYS (1<<14)
-#define OPTIMIZER_SWITCH_OUTER_JOIN_WITH_CACHE (1<<15)
-#define OPTIMIZER_SWITCH_SEMIJOIN_WITH_CACHE (1<<16)
-#define OPTIMIZER_SWITCH_JOIN_CACHE_INCREMENTAL (1<<17)
-#define OPTIMIZER_SWITCH_JOIN_CACHE_HASHED (1<<18)
-#define OPTIMIZER_SWITCH_JOIN_CACHE_BKA (1<<19)
-#define OPTIMIZER_SWITCH_OPTIMIZE_JOIN_BUFFER_SIZE (1<<20)
+/** If this is off, MRR is never used. */
+#define OPTIMIZER_SWITCH_MRR                       (1ULL << 14)
+/**
+   If OPTIMIZER_SWITCH_MRR is on and this is on, MRR is used depending on a
+   cost-based choice ("automatic"). If OPTIMIZER_SWITCH_MRR is on and this is
+   off, MRR is "forced" (i.e. used as long as the storage engine is capable of
+   doing it).
+*/
+#define OPTIMIZER_SWITCH_MRR_COST_BASED            (1ULL << 15)
+#define OPTIMIZER_SWITCH_MRR_SORT_KEYS             (1ULL << 16)
+#define OPTIMIZER_SWITCH_OUTER_JOIN_WITH_CACHE     (1ULL << 17)
+#define OPTIMIZER_SWITCH_SEMIJOIN_WITH_CACHE       (1ULL << 18)
+#define OPTIMIZER_SWITCH_JOIN_CACHE_INCREMENTAL    (1ULL << 19)
+#define OPTIMIZER_SWITCH_JOIN_CACHE_HASHED         (1ULL << 20)
+#define OPTIMIZER_SWITCH_JOIN_CACHE_BKA            (1ULL << 21)
+#define OPTIMIZER_SWITCH_OPTIMIZE_JOIN_BUFFER_SIZE (1ULL << 22)
 #ifdef DBUG_OFF
-#  define OPTIMIZER_SWITCH_LAST (1<<21)
+#  define OPTIMIZER_SWITCH_LAST                    (1ULL << 23)
 #else
-#  define OPTIMIZER_SWITCH_TABLE_ELIMINATION (1<<21)
-#  define OPTIMIZER_SWITCH_LAST (1<<22)
+#  define OPTIMIZER_SWITCH_TABLE_ELIMINATION       (1ULL << 23)
+#  define OPTIMIZER_SWITCH_LAST                    (1ULL << 24)
 #endif
 
 #ifdef DBUG_OFF 
@@ -608,6 +617,7 @@ enabled by default, add OPTIMIZER_SWITCH_MATERIALIZATION
                                     OPTIMIZER_SWITCH_PARTIAL_MATCH_ROWID_MERGE|\
                                     OPTIMIZER_SWITCH_PARTIAL_MATCH_TABLE_SCAN|\
                                     OPTIMIZER_SWITCH_SUBQUERY_CACHE|\
+                                    OPTIMIZER_SWITCH_MRR|\
                                     OPTIMIZER_SWITCH_MRR_SORT_KEYS|\
                                     OPTIMIZER_SWITCH_SUBQUERY_CACHE | \
                                     OPTIMIZER_SWITCH_JOIN_CACHE_INCREMENTAL | \
@@ -628,6 +638,7 @@ enabled by default, add OPTIMIZER_SWITCH_MATERIALIZATION
                                     OPTIMIZER_SWITCH_PARTIAL_MATCH_ROWID_MERGE|\
                                     OPTIMIZER_SWITCH_PARTIAL_MATCH_TABLE_SCAN|\
                                     OPTIMIZER_SWITCH_SUBQUERY_CACHE|\
+                                    OPTIMIZER_SWITCH_MRR|\
                                     OPTIMIZER_SWITCH_MRR_SORT_KEYS|\
                                     OPTIMIZER_SWITCH_JOIN_CACHE_INCREMENTAL | \
                                     OPTIMIZER_SWITCH_JOIN_CACHE_HASHED | \

sql/mysqld.cc

@@ -340,6 +340,8 @@ static const char *optimizer_switch_names[]=
   "partial_match_rowid_merge",
   "partial_match_table_scan",
   "subquery_cache",
+  "mrr",
+  "mrr_cost_based",
   "mrr_sort_keys",
   "outer_join_with_cache",
   "semijoin_with_cache",
@@ -370,6 +372,8 @@ static const unsigned int optimizer_switch_names_len[]=
   sizeof("partial_match_rowid_merge") - 1,
   sizeof("partial_match_table_scan") - 1,
   sizeof("subquery_cache") - 1,
+  sizeof("mrr") - 1,
+  sizeof("mrr_cost_based") - 1,
   sizeof("mrr_sort_keys") - 1,
   sizeof("outer_join_with_cache") - 1,
   sizeof("semijoin_with_cache") - 1,
@@ -487,6 +491,8 @@ static const char *optimizer_switch_str="index_merge=on,index_merge_union=on,"
                                         "partial_match_rowid_merge=on,"
                                         "partial_match_table_scan=on,"
                                         "subquery_cache=on,"
+                                        "mrr=on,"
+                                        "mrr_cost_based=off,"
                                         "mrr_sort_keys=on,"
                                         "join_cache_incremental=on,"
                                         "join_cache_hashed=on,"
@@ -3731,8 +3737,6 @@ static int init_common_variables(const char *conf_file_name, int argc,
   global_system_variables.character_set_results= default_charset_info;
   global_system_variables.character_set_client= default_charset_info;
 
-  global_system_variables.optimizer_use_mrr= 1;
-
   if (!(character_set_filesystem=
         get_charset_by_csname(character_set_filesystem_name,
                               MY_CS_PRIMARY, MYF(MY_WME))))

sql/set_var.cc

@@ -527,17 +527,6 @@ static sys_var_thd_ulong        sys_optimizer_search_depth(&vars, "optimizer_sea
 static sys_var_thd_optimizer_switch   sys_optimizer_switch(&vars, "optimizer_switch",
                                      &SV::optimizer_switch);
 
-const char *optimizer_use_mrr_names[] = {"auto", "force", "disable", NullS};
-TYPELIB optimizer_use_mrr_typelib= {
-  array_elements(optimizer_use_mrr_names) - 1, "",
-  optimizer_use_mrr_names, NULL
-};
-
-static sys_var_thd_enum        sys_optimizer_use_mrr(&vars, "optimizer_use_mrr",
-                                              &SV::optimizer_use_mrr,
-                                              &optimizer_use_mrr_typelib,
-                                              NULL);
-
 static sys_var_const            sys_pid_file(&vars, "pid_file",
                                              OPT_GLOBAL, SHOW_CHAR,
                                              (uchar*) pidfile_name);

sql/sql_class.h

@@ -408,14 +408,6 @@ struct system_variables
   ulong optimizer_search_depth;
   /* A bitmap for switching optimizations on/off */
   ulong optimizer_switch;
-  /*
-    Controls use of Engine-MRR:
-      0 - auto, based on cost
-      1 - force MRR when the storage engine is capable of doing it
-      2 - disable MRR.
-  */
-  ulong optimizer_use_mrr; 
-
   ulong preload_buff_size;
   ulong profiling_history_size;
   ulong query_cache_type;