Post-merge fixes part#2

mysql-test/r/subselect.result

@@ -2831,7 +2831,7 @@ Note	1003	select `test`.`t1`.`one` AS `one`,`test`.`t1`.`two` AS `two`,<expr_cac
 explain extended SELECT one,two from t1 where ROW(one,two) IN (SELECT one,two FROM t2 WHERE flag = 'N');
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	8	100.00	
-1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	10	func,func	1	100.00	
+1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	9	100.00	Using where; FirstMatch(t1)
 Warnings:
 Note	1003	select `test`.`t1`.`one` AS `one`,`test`.`t1`.`two` AS `two` from `test`.`t1` semi join (`test`.`t2`) where ((`test`.`t2`.`two` = `test`.`t1`.`two`) and (`test`.`t2`.`one` = `test`.`t1`.`one`) and (`test`.`t2`.`flag` = 'N'))
 explain extended SELECT one,two,ROW(one,two) IN (SELECT one,two FROM t2 WHERE flag = '0' group by one,two) as 'test' from t1;
@@ -3429,7 +3429,7 @@ AAA	8
 EXPLAIN
 SELECT * FROM t1 WHERE (a,b) = ANY (SELECT a, max(b) FROM t1 GROUP BY a);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	t1	ALL	a	NULL	NULL	NULL	9	Using where
+1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	9	Using where
 2	DEPENDENT SUBQUERY	t1	index	NULL	a	8	NULL	1	
 DROP TABLE t1;
 create table t1( f1 int,f2 int);

mysql-test/r/subselect4.result

+drop table if exists t1,t2,t3,t4,t5,t6;
 #
 # Bug #46791: Assertion failed:(table->key_read==0),function unknown
 #    function,file sql_base.cc
@@ -735,6 +736,7 @@ WHERE ( t1.f10 ) IN ( SELECT f11 FROM t2 GROUP BY f11 ));
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE noticed after reading const tables
 2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	2	Using where
+2	SUBQUERY	<subquery3>	eq_ref	distinct_key	distinct_key	5	test.t1.f10	1	
 3	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	2	Using temporary
 SELECT * FROM t1
 WHERE f3 = (
@@ -749,6 +751,7 @@ WHERE ( f10, f10 ) IN ( SELECT f11, f11 FROM t2 GROUP BY f11 ));
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE noticed after reading const tables
 2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	2	Using where
+2	SUBQUERY	<subquery3>	eq_ref	distinct_key	distinct_key	10	test.t1.f10,test.t1.f10	1	
 3	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	2	Using temporary
 SELECT * FROM t1
 WHERE f3 = (

mysql-test/r/subselect_sj.result

@@ -961,7 +961,7 @@ FROM t1
 WHERE `varchar_nokey`  < 'n' XOR `pk`  )   ;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	18	100.00	
-1	PRIMARY	t1	ref	varchar_key	varchar_key	3	test.t2.varchar_nokey	2	105.00	Using where; FirstMatch(t2)
+1	PRIMARY	t1	ref	varchar_key	varchar_key	3	test.t2.varchar_nokey	2	100.00	Using where; FirstMatch(t2)
 Warnings:
 Note	1003	select `test`.`t2`.`varchar_nokey` AS `varchar_nokey` from `test`.`t2` semi join (`test`.`t1`) where ((`test`.`t1`.`varchar_key` = `test`.`t2`.`varchar_nokey`) and (`test`.`t1`.`varchar_nokey` = `test`.`t2`.`varchar_nokey`) and ((`test`.`t2`.`varchar_nokey` < 'n') xor `test`.`t1`.`pk`))
 SELECT varchar_nokey

mysql-test/r/subselect_sj2_mat.result

@@ -33,7 +33,7 @@ a	b
 9	5
 explain select * from t2 where b in (select a from t1);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	subselect2	ALL	unique_key	NULL	NULL	NULL	3	
+1	PRIMARY	<subquery2>	ALL	distinct_key	NULL	NULL	NULL	3	
 1	PRIMARY	t2	ref	b	b	5	test.t1.a	2	
 2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	3	Using where
 select * from t2 where b in (select a from t1);
@@ -53,7 +53,7 @@ insert into t3 select a,a, a,a,a from t0;
 explain select * from t3 where b in (select a from t1);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t3	ALL	b	NULL	NULL	NULL	10	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	5	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	5	func	1	
 2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	3	
 select * from t3 where b in (select a from t1);
 a	b	pk1	pk2	pk3
@@ -76,7 +76,7 @@ A.a + 10*B.a, A.a + 10*B.a, A.a + 10*B.a, A.a + 10*B.a
 from t0 A, t0 B where B.a <5;
 explain select * from t3 where b in (select a from t0);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	subselect2	ALL	unique_key	NULL	NULL	NULL	10	
+1	PRIMARY	<subquery2>	ALL	distinct_key	NULL	NULL	NULL	10	
 1	PRIMARY	t3	ref	b	b	5	test.t0.a	1	
 2	SUBQUERY	t0	ALL	NULL	NULL	NULL	NULL	10	Using where
 set @save_ecp= @@engine_condition_pushdown;
@@ -103,7 +103,7 @@ set max_heap_table_size= @save_max_heap_table_size;
 explain select * from t1 where a in (select b from t2);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	5	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	5	func	1	
 2	SUBQUERY	t2	index	b	b	5	NULL	10	Using index
 select * from t1;
 a	b
@@ -131,7 +131,7 @@ explain select
 a, mid(filler1, 1,10), length(filler1)=length(filler2) as Z 
 from t1 ot where a in (select a from t2 it);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	subselect2	ALL	unique_key	NULL	NULL	NULL	22	
+1	PRIMARY	<subquery2>	ALL	distinct_key	NULL	NULL	NULL	22	
 1	PRIMARY	ot	ALL	NULL	NULL	NULL	NULL	32	Using where; Using join buffer (flat, BNL join)
 2	SUBQUERY	it	ALL	NULL	NULL	NULL	NULL	22	
 select 
@@ -165,7 +165,7 @@ a, mid(filler1, 1,10), length(filler1)=length(filler2)
 from t2 ot where a in (select a from t1 it);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	ot	ALL	NULL	NULL	NULL	NULL	22	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	5	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	5	func	1	
 2	SUBQUERY	it	ALL	NULL	NULL	NULL	NULL	32	
 select 
 a, mid(filler1, 1,10), length(filler1)=length(filler2) 
@@ -199,7 +199,7 @@ explain select
 a, mid(filler1, 1,10), length(filler1)=length(filler2) as Z 
 from t1 ot where a in (select a from t2 it);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	PRIMARY	subselect2	ALL	unique_key	NULL	NULL	NULL	22	
+1	PRIMARY	<subquery2>	ALL	distinct_key	NULL	NULL	NULL	22	
 1	PRIMARY	ot	ALL	NULL	NULL	NULL	NULL	52	Using where; Using join buffer (flat, BNL join)
 2	SUBQUERY	it	ALL	NULL	NULL	NULL	NULL	22	
 select 
@@ -233,7 +233,7 @@ a, mid(filler1, 1,10), length(filler1)=length(filler2)
 from t2 ot where a in (select a from t1 it);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	ot	ALL	NULL	NULL	NULL	NULL	22	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	5	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	5	func	1	
 2	SUBQUERY	it	ALL	NULL	NULL	NULL	NULL	52	
 select 
 a, mid(filler1, 1,10), length(filler1)=length(filler2) 
@@ -350,7 +350,7 @@ WHERE t1.Code IN (
 SELECT t2.CountryCode FROM t2 WHERE Population > 5000000);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t1	ALL	PRIMARY	NULL	NULL	NULL	31	
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	3	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	3	func	1	
 2	SUBQUERY	t2	ALL	CountryCode	NULL	NULL	NULL	545	Using where
 SELECT Name FROM t1 
 WHERE t1.Code IN (
@@ -361,6 +361,10 @@ Canada
 China
 Czech Republic
 drop table t1, t2;
+drop procedure if exists p1;
+drop procedure if exists p2;
+drop procedure if exists p3;
+drop procedure if exists p4;
 CREATE TABLE t1(a INT);
 CREATE TABLE t2(c INT);
 CREATE PROCEDURE p1(v1 int)
@@ -694,7 +698,7 @@ The following must use loose index scan over t3, key a:
 explain select count(a) from t2 where a in ( SELECT  a FROM t3);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t2	index	a	a	5	NULL	1000	Using index
-1	PRIMARY	subselect2	eq_ref	unique_key	unique_key	5	func	1	
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	5	func	1	
 2	SUBQUERY	t3	index	a	a	5	NULL	30000	Using index
 select count(a) from t2 where a in ( SELECT  a FROM t3);
 count(a)

mysql-test/r/subselect_sj_jcl6.result

@@ -969,7 +969,7 @@ FROM t1
 WHERE `varchar_nokey`  < 'n' XOR `pk`  )   ;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	PRIMARY	t2	ALL	NULL	NULL	NULL	NULL	18	100.00	
-1	PRIMARY	t1	ref	varchar_key	varchar_key	3	test.t2.varchar_nokey	2	105.00	Using where; FirstMatch(t2); Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan
+1	PRIMARY	t1	ref	varchar_key	varchar_key	3	test.t2.varchar_nokey	2	100.00	Using where; FirstMatch(t2); Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan
 Warnings:
 Note	1003	select `test`.`t2`.`varchar_nokey` AS `varchar_nokey` from `test`.`t2` semi join (`test`.`t1`) where ((`test`.`t1`.`varchar_key` = `test`.`t2`.`varchar_nokey`) and (`test`.`t1`.`varchar_nokey` = `test`.`t2`.`varchar_nokey`) and ((`test`.`t2`.`varchar_nokey` < 'n') xor `test`.`t1`.`pk`))
 SELECT varchar_nokey

mysql-test/r/subselect_sj_nonmerged.result

 drop table if exists t0, t1, t2, t3, t4;
 set @save_optimizer_switch=@@optimizer_switch;
+set optimizer_switch='materialization=on';
 create table t0 (a int);
 insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
 create table t1 as select * from t0;
@@ -40,14 +41,14 @@ explain select * from t3 where a in (select max(t2.a) from t1, t2 group by t2.b)
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	<subquery2>	ALL	distinct_key	NULL	NULL	NULL	5	Using where
 1	PRIMARY	t3	eq_ref	PRIMARY	PRIMARY	8	<subquery2>.max(t2.a)	1	Using where; Using index
-2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	5	Using temporary; Using filesort
+2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	5	Using temporary
 2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	10	Using join buffer (flat, BNL join)
 # Compare to this which really will have 50 record combinations:
 explain select * from t3 where a in (select max(t2.a) from t1, t2 group by t2.b, t1.b);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	<subquery2>	ALL	distinct_key	NULL	NULL	NULL	50	Using where
 1	PRIMARY	t3	eq_ref	PRIMARY	PRIMARY	8	<subquery2>.max(t2.a)	1	Using where; Using index
-2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	5	Using temporary; Using filesort
+2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	5	Using temporary
 2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	10	Using join buffer (flat, BNL join)
 # Outer joins also work:
 explain select * from t3 
@@ -55,7 +56,7 @@ where a in (select max(t2.a) from t1 left join t2 on t1.a=t2.a group by t2.b, t1
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	<subquery2>	ALL	distinct_key	NULL	NULL	NULL	50	Using where
 1	PRIMARY	t3	eq_ref	PRIMARY	PRIMARY	8	<subquery2>.max(t2.a)	1	Using where; Using index
-2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	10	Using temporary; Using filesort
+2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	10	Using temporary
 2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	5	Using where
 create table t4 (a int, b int, filler char(20), unique key(a,b));
 insert into t4 select A.a + 10*B.a, A.a + 10*B.a, 'filler' from t0 A, t0 B;
@@ -65,7 +66,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t0	ALL	NULL	NULL	NULL	NULL	10	
 1	PRIMARY	t4	ALL	a	NULL	NULL	NULL	100	Using where; Using join buffer (flat, BNL join)
 1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	5	test.t4.a	1	
-2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	5	Using temporary; Using filesort
+2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	5	Using temporary
 2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	10	Using join buffer (flat, BNL join)
 insert into t4 select 100 + (B.a *100 + A.a), 100 + (B.a*100 + A.a), 'filler' from t4 A, t0 B;
 explain select * from t4 where 
@@ -75,9 +76,9 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	<subquery2>	ALL	distinct_key	NULL	NULL	NULL	5	Using where
 1	PRIMARY	<subquery3>	ALL	distinct_key	NULL	NULL	NULL	5	Using where; Using join buffer (flat, BNL join)
 1	PRIMARY	t4	ref	a	a	10	<subquery2>.max(t2.a),<subquery3>.max(t2.a)	12	
-3	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	5	Using temporary; Using filesort
+3	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	5	Using temporary
 3	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	10	Using join buffer (flat, BNL join)
-2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	5	Using temporary; Using filesort
+2	SUBQUERY	t2	ALL	NULL	NULL	NULL	NULL	5	Using temporary
 2	SUBQUERY	t1	ALL	NULL	NULL	NULL	NULL	10	Using join buffer (flat, BNL join)
 drop table t1,t2,t3,t4;
 drop table t0;
@@ -99,3 +100,4 @@ GROUP BY 1
 );
 f1
 DROP TABLE t1, t2;
+set optimizer_switch=@save_optimizer_switch;

mysql-test/t/subselect_mat.test

@@ -9,13 +9,6 @@ set @@optimizer_switch='materialization=on,in_to_exists=off,semijoin=off';
 
 --source t/subselect_sj_mat.test
 set @@optimizer_switch='materialization=on,in_to_exists=off,semijoin=off';
-set @@optimizer_switch='materialization=on,in_to_exists=off,semijoin=off';
-explain select min(a1) from t1 where 7 in (select b1 from t2);
-select min(a1) from t1 where 7 in (select b1 from t2);
-# Executed via IN=>EXISTS
-set @@optimizer_switch='materialization=off,in_to_exists=on,semijoin=off';
-
-set @@optimizer_switch=default;
 #
 # Test that the contents of the temp table of a materialized subquery is
 # cleaned up between PS re-executions.

mysql-test/t/subselect_sj_mat.test

@@ -3,7 +3,6 @@
 # (WL#1110: Subquery optimization: materialization)
 #
 
-set optimizer_switch='firstmatch=off';
 --disable_warnings
 drop table if exists t1, t2, t3, t1i, t2i, t3i;
 drop view if exists v1, v2, v1m, v2m;
@@ -48,6 +47,8 @@ insert into t1i select * from t1;
 insert into t2i select * from t2;
 insert into t3i select * from t3;
 
+# force the use of materialization
+set @@optimizer_switch='materialization=on,in_to_exists=off,firstmatch=off';
 
 /******************************************************************************
 * Simple tests.
@@ -920,8 +921,8 @@ set session optimizer_switch=@save_optimizer_switch;
 drop table t1, t2, t3;
 
 #
-# Test that the contentes of the temp table of a materialized subquery is
-# cleanup up between PS reexecutions.
+# Test that the contents of the temp table of a materialized subquery is
+# cleaned up between PS re-executions.
 #
 
 create table t0 (a int);
@@ -969,4 +970,3 @@ explain select left(a1,7), left(a2,7) from t1_1024 where (a1,3) in (select subst
 select left(a1,7), left(a2,7) from t1_1024 where (a1,3) in (select substring(b1,1,1024), count(*) from t2_1024 where b1 > '0');
 
 drop table t1_1024, t2_1024;
-

mysql-test/t/subselect_sj_nonmerged.test

@@ -6,6 +6,7 @@ drop table if exists t0, t1, t2, t3, t4;
 --enable_warnings
 
 set @save_optimizer_switch=@@optimizer_switch;
+set optimizer_switch='materialization=on';
 
 create table t0 (a int);
 insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
@@ -94,4 +95,5 @@ WHERE ( f1 ) IN (
 );
 
 DROP TABLE t1, t2;
+set optimizer_switch=@save_optimizer_switch;
 

sql/opt_subselect.cc

@@ -353,7 +353,7 @@ int check_and_do_in_subquery_rewrites(JOIN *join)
     }
     else
     {
-      DBUG_PRINT("info", ("Subquery can't be converted to semi-join"));
+      DBUG_PRINT("info", ("Subquery can't be converted to merged semi-join"));
       /* Test if the user has set a legal combination of optimizer switches. */
       if (!optimizer_flag(thd, OPTIMIZER_SWITCH_IN_TO_EXISTS) &&
           !optimizer_flag(thd, OPTIMIZER_SWITCH_MATERIALIZATION))
@@ -395,7 +395,8 @@ int check_and_do_in_subquery_rewrites(JOIN *join)
         join->sj_subselects list to be populated for every EXECUTE. 
 
         */
-        if (!select_lex->is_part_of_union() &&                            // 1
+        if (optimizer_flag(thd, OPTIMIZER_SWITCH_MATERIALIZATION) && 
+            !select_lex->is_part_of_union() &&                            // 1
             parent_unit->first_select()->leaf_tables &&                   // 2
             thd->lex->sql_command == SQLCOM_SELECT &&                     // *
             select_lex->outer_select()->leaf_tables &&                    // 2A
@@ -888,8 +889,6 @@ void get_delayed_table_estimates(TABLE *table,
                                  double *startup_cost)
 {
   Item_in_subselect *item= table->pos_in_table_list->jtbm_subselect;
-  double rows;
-  double read_time;
 
   //psergey-merge: moving off here: item->optimize(&rows, &read_time);
 
@@ -899,10 +898,11 @@ void get_delayed_table_estimates(TABLE *table,
   subselect_hash_sj_engine *hash_sj_engine=
     ((subselect_hash_sj_engine*)item->engine);
 
-  *out_rows= (ha_rows)rows;
-  *startup_cost= read_time;
+  *out_rows= (ha_rows)item->jtbm_record_count;
+  *startup_cost= item->jtbm_read_time;
+
   /* Calculate cost of scanning the temptable */
-  double data_size= rows * hash_sj_engine->tmp_table->s->reclength;
+  double data_size= (*out_rows) * hash_sj_engine->tmp_table->s->reclength;
   /* Do like in handler::read_time */
   *scan_time= data_size/IO_SIZE + 2;
 } 
@@ -1326,6 +1326,9 @@ static bool convert_subq_to_jtbm(JOIN *parent_join,
   //  DBUG_RETURN(TRUE);
   double rows;
   double read_time;
+
+  // psergey-merge: disable IN->EXISTS for JTBM subqueries, for now.
+  subq_pred->in_strategy &= ~SUBS_IN_TO_EXISTS;
   subq_pred->optimize(&rows, &read_time);
 
   subq_pred->jtbm_read_time= read_time;
@@ -1710,10 +1713,16 @@ bool optimize_semijoin_nests(JOIN *join, table_map all_table_map)
         sjm->tables= n_tables;
         sjm->is_used= FALSE;
         double subjoin_out_rows, subjoin_read_time;
+
+        /*
         join->get_partial_cost_and_fanout(n_tables + join->const_tables,
                                           table_map(-1),
                                           &subjoin_read_time, 
                                           &subjoin_out_rows);
+        */
+        join->get_prefix_cost_and_fanout(n_tables, 
+                                         &subjoin_read_time,
+                                         &subjoin_out_rows);
 
         sjm->materialization_cost.convert_from_cost(subjoin_read_time);
         sjm->rows= subjoin_out_rows;

sql/sql_select.cc

@@ -5935,6 +5935,36 @@ void JOIN::get_partial_cost_and_fanout(uint end_tab_idx,
 }
 
 
+/*
+  Get prefix cost and fanout. This function is different from
+  get_partial_cost_and_fanout:
+   - it operates on a JOIN that haven't yet finished its optimization phase (in
+     particular, fix_semijoin_strategies_for_picked_join_order() and
+     get_best_combination() haven't been called)
+   - it assumes the the join prefix doesn't have any semi-join plans
+
+  These assumptions are met by the caller of the function.
+*/
+
+void JOIN::get_prefix_cost_and_fanout(uint n_tables, 
+                                      double *read_time_arg,
+                                      double *record_count_arg)
+{
+  double record_count= 1;
+  double read_time= 0.0;
+  for (uint i= const_tables; i < n_tables + const_tables ; i++)
+  {
+    if (best_positions[i].records_read)
+    {
+      record_count *= best_positions[i].records_read;
+      read_time += best_positions[i].read_time;
+    }
+  }
+  *read_time_arg= read_time;// + record_count / TIME_FOR_COMPARE;
+  *record_count_arg= record_count;
+}
+
+
 /**
   Find a good, possibly optimal, query execution plan (QEP) by a possibly
   exhaustive search.

sql/sql_select.h

@@ -1138,12 +1138,13 @@ public:
            max_allowed_join_cache_level > JOIN_CACHE_HASHED_BIT;
   }
   bool choose_subquery_plan(table_map join_tables);
-  //void get_partial_join_cost(uint n_tables,
-  //                           double *read_time_arg, double *record_count_arg);
   void get_partial_cost_and_fanout(uint end_tab_idx,
                                    table_map filter_map,
                                    double *read_time_arg, 
                                    double *record_count_arg);
+  void get_prefix_cost_and_fanout(uint n_tables, 
+                                  double *read_time_arg,
+                                  double *record_count_arg);
 private:
   /**
     TRUE if the query contains an aggregate function but has no GROUP