added depended subselect processing

mysql-test/r/subselect.result

@@ -6,6 +6,14 @@ create table t4 (a int, b int);
 insert into t1 values (2);
 insert into t2 values (1,7),(2,7);
 insert into t4 values (4,8),(3,8),(5,9);
+select (select a from t1 where t1.a=t2.a), a from t2;
+(select a from t1 where t1.a=t2.a)	a
+NULL	1
+2	2
+select (select a from t1 where t1.a=t2.b), a from t2;
+(select a from t1 where t1.a=t2.b)	a
+NULL	1
+NULL	2
 select (select a from t1), a from t2;
 (select a from t1)	a
 2	1

mysql-test/t/subselect.test

@@ -8,6 +8,8 @@ create table t4 (a int, b int);
 insert into t1 values (2);
 insert into t2 values (1,7),(2,7);
 insert into t4 values (4,8),(3,8),(5,9);
+select (select a from t1 where t1.a=t2.a), a from t2;
+select (select a from t1 where t1.a=t2.b), a from t2;
 select (select a from t1), a from t2;
 select (select a from t3), a from t2;
 select * from t2 where t2.a=(select a from t1);

sql/item.cc

@@ -320,7 +320,34 @@ bool Item_field::fix_fields(THD *thd,TABLE_LIST *tables)
   {
     Field *tmp;
     if (!(tmp=find_field_in_tables(thd,this,tables)))
-      return 1;
+    {
+      /*
+	We can't find table field in table list of current select, 
+	consequently we have to find it in outer subselect(s).
+	We can't join lists of outer & current select, because of scope 
+	of view rules. For example if both tables (outer & current) have 
+	field 'field' it is not mistake to refer to this field without 
+	mention of table name, but if we join tables in one list it will
+	cause error ER_NON_UNIQ_ERROR in find_field_in_tables.
+      */
+      for (SELECT_LEX *sl= thd->lex.select->outer_select();
+	   sl && !tmp;
+	   sl= sl->outer_select())
+	tmp=find_field_in_tables(thd, this,
+				 (TABLE_LIST*)sl->table_list.first);
+      if (!tmp)
+	return 1;
+      else
+	if( !thd->lex.select->depended )
+	{
+	  thd->lex.select->depended= 1; //Select is depended of outer select(s)
+	  //Tables will be reopened many times
+	  for (TABLE_LIST *tbl= (TABLE_LIST*)thd->lex.select->table_list.first;
+	       tbl;
+	       tbl= tbl->next)
+	    tbl->shared= 1;
+	}
+    }
     set_field(tmp);
   }
   else if (thd && thd->set_query_id && field->query_id != thd->query_id)

sql/item_subselect.cc

@@ -36,7 +36,7 @@ SUBSELECT TODO:
 #include "sql_select.h"
 
 Item_subselect::Item_subselect(THD *thd, st_select_lex *select_lex):
-  executed(0)
+  executed(0), optimized(0), error(0)
 {
   DBUG_ENTER("Item_subselect::Item_subselect");
   DBUG_PRINT("subs", ("select_lex 0x%xl", (long) select_lex));
@@ -48,7 +48,7 @@ Item_subselect::Item_subselect(THD *thd, st_select_lex *select_lex):
     item value is NULL if select_subselect not changed this value 
     (i.e. some rows will be found returned)
   */
-  assign_null(); 
+  assign_null();
   DBUG_VOID_RETURN;
 }
 
@@ -110,17 +110,31 @@ bool Item_subselect::fix_fields(THD *thd,TABLE_LIST *tables)
 		   (ORDER*) 0, select_lex, 
 		   (SELECT_LEX_UNIT*) select_lex->master))
     return 1;
-  if (join->optimize())
-  {
-    executed= 1;
-    return 1;
-  }
   thd->lex.select= save_select;
   return 0;
 }
 
 int Item_subselect::exec()
 {
+  if (!optimized)
+  {
+    optimized=1;
+    if (join->optimize())
+    {
+      executed= 1;
+      return (join->error?join->error:1);
+    }
+  }
+  if (join->select_lex->depended && executed)
+  {
+    if (join->reinit())
+    {
+      error= 1;
+      return 1;
+    }
+    assign_null();
+    executed= 0;
+  }
   if (!executed)
   {
     SELECT_LEX *save_select= join->thd->lex.select;

sql/item_subselect.h

@@ -29,9 +29,11 @@ class select_subselect;
 class Item_subselect :public Item
 {
 protected:
-  my_bool executed; /* simple subselect is executed */
   longlong int_value;
   double real_value;
+  my_bool executed; /* simple subselect is executed */
+  my_bool optimized; /* simple subselect is optimized */
+  my_bool error; /* error in query */
   enum Item_result res_type;
 
   int exec();
@@ -62,6 +64,7 @@ public:
     join= item->join;
     result= item->result;
     name= item->name;
+    error= item->error;
   }
   enum Type type() const;
   double val ();

sql/sql_lex.cc

@@ -931,6 +931,7 @@ void st_select_lex::init_select()
   use_index.empty();
   ftfunc_list.empty();
   linkage=UNSPECIFIED_TYPE;
+  depended= 0;
 }
 
 /*

sql/sql_lex.h

@@ -208,6 +208,7 @@ private:
    SELECT_LEXs
 */
 struct st_lex;
+struct st_select_lex;
 struct st_select_lex_unit: public st_select_lex_node {
   /*
     Pointer to 'last' select or pointer to unit where stored
@@ -218,6 +219,8 @@ struct st_select_lex_unit: public st_select_lex_node {
   ha_rows select_limit_cnt, offset_limit_cnt;
   void init_query();
   bool create_total_list(THD *thd, st_lex *lex, TABLE_LIST **result);
+  st_select_lex* first_select() { return (st_select_lex*) slave; }
+  st_select_lex_unit* next_unit() { return (st_select_lex_unit*) next; }
 private:
   bool create_total_list_n_last_return(THD *thd, st_lex *lex,
 				       TABLE_LIST ***result);
@@ -240,9 +243,12 @@ struct st_select_lex: public st_select_lex_node {
   List<Item_func_match> ftfunc_list;
   uint in_sum_expr, sort_default;
   bool	create_refs, 
-    braces; /* SELECT ... UNION (SELECT ... ) <- this braces */
+    braces,   /* SELECT ... UNION (SELECT ... ) <- this braces */
+    depended; /* depended from outer select subselect */
   void init_query();
   void init_select();
+  st_select_lex* outer_select() { return (st_select_lex*) master->master; }
+  st_select_lex* next_select() { return (st_select_lex*) next; }
 };
 typedef struct st_select_lex SELECT_LEX;
 

sql/sql_select.cc

@@ -213,7 +213,8 @@ JOIN::prepare(TABLE_LIST *tables_init,
   proc_param= proc_param_init;
   tables_list= tables_init;
   select_lex= select;
-
+  union_part= (unit->first_select()->next_select() != 0);
+  
   /* Check that all tables, fields, conds and order are ok */
 
   if (setup_tables(tables_list) ||
@@ -334,7 +335,6 @@ int
 JOIN::optimize()
 {
   DBUG_ENTER("JOIN::optimize");
-  SELECT_LEX *select_lex = &(thd->lex.select_lex);
 
 #ifdef HAVE_REF_TO_FIELDS			// Not done yet
   /* Add HAVING to WHERE if possible */
@@ -380,7 +380,7 @@ JOIN::optimize()
       }
       if (select_options & SELECT_DESCRIBE)
       {
-	if (select_lex->next)
+	if (union_part)
 	  select_describe(this, false, false, false,
 			  "Select tables optimized away");
 	else
@@ -406,6 +406,17 @@ JOIN::optimize()
   if (make_join_statistics(this, tables_list, conds, &keyuse) ||
       thd->fatal_error)
     DBUG_RETURN(-1);
+
+  if (select_lex->depended)
+  {
+    /*
+      Just remove all const-table optimization in case of depended query
+      TODO: optimize
+    */
+    const_table_map= 0;
+    const_tables= 0;
+    found_const_table_map= 0;
+  }
   thd->proc_info= "preparing";
   result->initialize_tables(this);
   if (const_table_map != found_const_table_map &&
@@ -576,7 +587,7 @@ JOIN::optimize()
 }
 
 /*
-  global uptimisation (with subselect) must be here (TODO)
+  Global optimization (with subselect) must be here (TODO)
 */
 
 int
@@ -585,8 +596,25 @@ JOIN::global_optimize()
   return 0;
 }
 
+int
+JOIN::reinit()
+{
+  DBUG_ENTER("JOIN::reinit");
+  //TODO move to unit reinit
+  unit->offset_limit_cnt =select_lex->offset_limit;
+  unit->select_limit_cnt =select_lex->select_limit+select_lex->offset_limit;
+  if (unit->select_limit_cnt < select_lex->select_limit)
+    unit->select_limit_cnt= HA_POS_ERROR;		// no limit
+  if (unit->select_limit_cnt == HA_POS_ERROR)
+    select_lex->options&= ~OPTION_FOUND_ROWS;
+
+  if (setup_tables(tables_list))
+    DBUG_RETURN(1);
+  DBUG_RETURN(0);
+}
+
 /*
-  exec select
+  Exec select
 */
 void
 JOIN::exec()
@@ -600,7 +628,7 @@ JOIN::exec()
     error=0;
     if (select_options & SELECT_DESCRIBE)
     {
-      if (select_lex->next)
+      if (union_part)
 	select_describe(this, false, false, false, "No tables used");
       else
 	describe_info(thd, "No tables used");
@@ -627,7 +655,7 @@ JOIN::exec()
 
   if (zero_result_cause)
   {
-    if (select_options & SELECT_DESCRIBE && select_lex->next)
+    if (select_options & SELECT_DESCRIBE && union_part)
       select_describe(this, false, false, false, zero_result_cause);
     else
       error=return_zero_rows(result, tables_list, fields_list,

sql/sql_select.h

@@ -196,6 +196,8 @@ class JOIN :public Sql_alloc{
 
   my_bool test_function_query; // need to return select items 1 row
   const char *zero_result_cause; // not 0 if exec must return zero result
+  
+  my_bool union_part; // this subselect is part of union 
 
   JOIN(THD *thd, List<Item> &fields,
        ulong select_options, select_result *result):
@@ -236,6 +238,7 @@ class JOIN :public Sql_alloc{
 	      ORDER *proc_param, SELECT_LEX *select, SELECT_LEX_UNIT *unit);
   int optimize();
   int global_optimize();
+  int reinit();
   void exec();
   int cleanup(THD *thd);  
 };