Fixed the case when statistics were not getting read because

we had the statistics tables in the FROM list of the select.
The statistics for tables are not read in such cases, so we need
to check this case separately.

Author: Varun Gupta

mysql-test/r/stat_tables.result

@@ -728,6 +728,17 @@ pk
 4
 3
 drop table t1,t2;
+create table t1(a int,b int, key k1(a) );
+insert into t1 values(1,1),(2,2),(3,3);
+analyze table t1;
+Table	Op	Msg_type	Msg_text
+test.t1	analyze	status	Engine-independent statistics collected
+test.t1	analyze	status	OK
+select * from mysql.index_stats, t1 where index_name='k1' and t1.a > 1 and t1.b > 1;
+db_name	table_name	index_name	prefix_arity	avg_frequency	a	b
+test	t1	k1	1	1.0000	2	2
+test	t1	k1	1	1.0000	3	3
+drop table t1;
 set @@optimizer_use_condition_selectivity= @save_optimizer_use_condition_selectivity;
 set @save_optimizer_switch=@@optimizer_switch;
 set use_stat_tables=@save_use_stat_tables;

mysql-test/r/stat_tables_innodb.result

@@ -755,6 +755,17 @@ pk
 4
 3
 drop table t1,t2;
+create table t1(a int,b int, key k1(a) );
+insert into t1 values(1,1),(2,2),(3,3);
+analyze table t1;
+Table	Op	Msg_type	Msg_text
+test.t1	analyze	status	Engine-independent statistics collected
+test.t1	analyze	status	OK
+select * from mysql.index_stats, t1 where index_name='k1' and t1.a > 1 and t1.b > 1;
+db_name	table_name	index_name	prefix_arity	avg_frequency	a	b
+test	t1	k1	1	1.0000	2	2
+test	t1	k1	1	1.0000	3	3
+drop table t1;
 set @@optimizer_use_condition_selectivity= @save_optimizer_use_condition_selectivity;
 set @save_optimizer_switch=@@optimizer_switch;
 set use_stat_tables=@save_use_stat_tables;

mysql-test/t/stat_tables.test

@@ -492,6 +492,12 @@ CREATE TABLE t2 SELECT pk FROM t1 WHERE pk>2;
 select * from t2;
 drop table t1,t2;
 
+create table t1(a int,b int, key k1(a) );
+insert into t1 values(1,1),(2,2),(3,3);
+analyze table t1;
+select * from mysql.index_stats, t1 where index_name='k1' and t1.a > 1 and t1.b > 1;
+drop table t1;
+
 set @@optimizer_use_condition_selectivity= @save_optimizer_use_condition_selectivity;
 
 set @save_optimizer_switch=@@optimizer_switch;

sql/opt_range.cc

@@ -3050,7 +3050,7 @@ bool calculate_cond_selectivity_for_table(THD *thd, TABLE *table, Item **cond)
 
   if (thd->variables.optimizer_use_condition_selectivity > 2 &&
       !bitmap_is_clear_all(used_fields) &&
-      thd->variables.use_stat_tables > 0)
+      thd->variables.use_stat_tables > 0 && table->stats_is_read)
   {
     PARAM param;
     MEM_ROOT alloc;