Bug#11766594 59736: SELECT DISTINCT.. INCORRECT RESULT WITH DETERMINISTIC FUNCTION IN WHERE C

There is an optimization of DISTINCT in JOIN::optimize()
which depends on THD::used_tables value. Each SELECT statement
inside SP resets used_tables value(see mysql_select()) and it
leads to wrong result. The fix is to replace THD::used_tables
with LEX::used_tables.

mysql-test/r/sp.result

@@ -7053,6 +7053,25 @@ init_connect
 SET @@GLOBAL.init_connect= @old_init_connect;
 DROP PROCEDURE p2;
 DROP PROCEDURE p5;
+#
+# Bug#11766594  59736: SELECT DISTINCT.. INCORRECT RESULT WITH DETERMINISTIC FUNCTION IN WHERE C
+#
+CREATE TABLE t1 (a INT, b INT, KEY(b));
+CREATE TABLE t2 (c INT, d INT, KEY(c));
+INSERT INTO t1 VALUES (1,1),(1,1),(1,2);
+INSERT INTO t2 VALUES (1,1),(1,2);
+CREATE FUNCTION f1() RETURNS INT DETERMINISTIC
+BEGIN
+DECLARE a int;
+-- SQL statement inside
+SELECT 1 INTO a;
+RETURN a;
+END $
+SELECT COUNT(DISTINCT d) FROM t1, t2  WHERE a = c AND b = f1();
+COUNT(DISTINCT d)
+2
+DROP FUNCTION f1;
+DROP TABLE t1, t2;
 # ------------------------------------------------------------------
 # -- End of 5.1 tests
 # ------------------------------------------------------------------

mysql-test/t/sp.test

@@ -8350,6 +8350,33 @@ SET @@GLOBAL.init_connect= @old_init_connect;
 DROP PROCEDURE p2;
 DROP PROCEDURE p5;
 
+--echo #
+--echo # Bug#11766594  59736: SELECT DISTINCT.. INCORRECT RESULT WITH DETERMINISTIC FUNCTION IN WHERE C
+--echo #
+
+CREATE TABLE t1 (a INT, b INT, KEY(b));
+CREATE TABLE t2 (c INT, d INT, KEY(c));
+INSERT INTO t1 VALUES (1,1),(1,1),(1,2);
+INSERT INTO t2 VALUES (1,1),(1,2);
+
+DELIMITER $;
+
+CREATE FUNCTION f1() RETURNS INT DETERMINISTIC
+BEGIN
+  DECLARE a int;
+  -- SQL statement inside
+  SELECT 1 INTO a;
+  RETURN a;
+END $
+
+DELIMITER ;$
+
+SELECT COUNT(DISTINCT d) FROM t1, t2  WHERE a = c AND b = f1();
+
+DROP FUNCTION f1;
+DROP TABLE t1, t2;
+
+
 --echo # ------------------------------------------------------------------
 --echo # -- End of 5.1 tests
 --echo # ------------------------------------------------------------------

sql/sql_base.cc

@@ -7576,7 +7576,7 @@ bool setup_fields(THD *thd, Item **ref_pointer_array,
     if (item->with_sum_func && item->type() != Item::SUM_FUNC_ITEM &&
 	sum_func_list)
       item->split_sum_func(thd, ref_pointer_array, *sum_func_list);
-    thd->used_tables|= item->used_tables();
+    thd->lex->used_tables|= item->used_tables();
     thd->lex->current_select->cur_pos_in_select_list++;
   }
   thd->lex->current_select->is_item_list_lookup= save_is_item_list_lookup;
@@ -7923,7 +7923,7 @@ insert_fields(THD *thd, Name_resolution_context *context, const char *db_name,
       views and natural joins this update is performed inside the loop below.
     */
     if (table)
-      thd->used_tables|= table->map;
+      thd->lex->used_tables|= table->map;
 
     /*
       Initialize a generic field iterator for the current table reference.
@@ -8008,7 +8008,7 @@ insert_fields(THD *thd, Name_resolution_context *context, const char *db_name,
           field_table= nj_col->table_ref->table;
           if (field_table)
           {
-            thd->used_tables|= field_table->map;
+            thd->lex->used_tables|= field_table->map;
             field_table->covering_keys.intersect(field->part_of_key);
             field_table->merge_keys.merge(field->part_of_key);
             field_table->used_fields++;
@@ -8016,7 +8016,7 @@ insert_fields(THD *thd, Name_resolution_context *context, const char *db_name,
         }
       }
       else
-        thd->used_tables|= item->used_tables();
+        thd->lex->used_tables|= item->used_tables();
       thd->lex->current_select->cur_pos_in_select_list++;
     }
     /*

sql/sql_class.cc

@@ -649,7 +649,6 @@ THD::THD()
   is_slave_error= thread_specific_used= FALSE;
   hash_clear(&handler_tables_hash);
   tmp_table=0;
-  used_tables=0;
   cuted_fields= sent_row_count= row_count= 0L;
   limit_found_rows= 0;
   row_count_func= -1;

sql/sql_class.h

@@ -1734,13 +1734,6 @@ public:
   */
   ha_rows    examined_row_count;
 
-  /*
-    The set of those tables whose fields are referenced in all subqueries
-    of the query.
-    TODO: possibly this it is incorrect to have used tables in THD because
-    with more than one subquery, it is not clear what does the field mean.
-  */
-  table_map  used_tables;
   USER_CONN *user_connect;
   CHARSET_INFO *db_charset;
   /*

sql/sql_insert.cc

@@ -631,7 +631,7 @@ bool mysql_insert(THD *thd,TABLE_LIST *table_list,
   lock_type= table_list->lock_type;
 
   thd_proc_info(thd, "init");
-  thd->used_tables=0;
+  thd->lex->used_tables=0;
   values= its++;
   value_count= values->elements;
 
@@ -779,7 +779,7 @@ bool mysql_insert(THD *thd,TABLE_LIST *table_list,
     }
     else
     {
-      if (thd->used_tables)			// Column used in values()
+      if (thd->lex->used_tables)		      // Column used in values()
 	restore_record(table,s->default_values);	// Get empty record
       else
       {

sql/sql_lex.cc

@@ -360,6 +360,7 @@ void lex_start(THD *thd)
   lex->server_options.port= -1;
 
   lex->is_lex_started= TRUE;
+  lex->used_tables= 0;
   DBUG_VOID_RETURN;
 }
 

sql/sql_lex.h

@@ -1836,6 +1836,16 @@ typedef struct st_lex : public Query_tables_list
   uint create_select_pos;
   bool create_select_in_comment;
 
+  /*
+    The set of those tables whose fields are referenced in all subqueries
+    of the query.
+    TODO: possibly this it is incorrect to have used tables in LEX because
+    with subquery, it is not clear what does the field mean. To fix this
+    we should aggregate used tables information for selected expressions
+    into the select_lex.
+  */
+  table_map  used_tables;
+
   st_lex();
 
   virtual ~st_lex()

sql/sql_prepare.cc

@@ -1382,7 +1382,7 @@ static int mysql_test_select(Prepared_statement *stmt,
   if (open_normal_and_derived_tables(thd, tables, 0))
     goto error;
 
-  thd->used_tables= 0;                        // Updated by setup_fields
+  thd->lex->used_tables= 0;                        // Updated by setup_fields
 
   /*
     JOIN::prepare calls
@@ -1551,7 +1551,7 @@ static bool select_like_stmt_test(Prepared_statement *stmt,
   if (specific_prepare && (*specific_prepare)(thd))
     DBUG_RETURN(TRUE);
 
-  thd->used_tables= 0;                        // Updated by setup_fields
+  thd->lex->used_tables= 0;                        // Updated by setup_fields
 
   /* Calls JOIN::prepare */
   DBUG_RETURN(lex->unit.prepare(thd, 0, setup_tables_done_option));

sql/sql_select.cc

@@ -406,7 +406,7 @@ fix_inner_refs(THD *thd, List<Item> &all_fields, SELECT_LEX *select,
 
     if (!ref->fixed && ref->fix_fields(thd, 0))
       return TRUE;
-    thd->used_tables|= item->used_tables();
+    thd->lex->used_tables|= item->used_tables();
   }
   return false;
 }
@@ -1632,7 +1632,7 @@ JOIN::optimize()
 
     if (exec_tmp_table1->distinct)
     {
-      table_map used_tables= thd->used_tables;
+      table_map used_tables= thd->lex->used_tables;
       JOIN_TAB *last_join_tab= join_tab+tables-1;
       do
       {
@@ -2526,7 +2526,7 @@ mysql_select(THD *thd, Item ***rref_pointer_array,
     if (!(join= new JOIN(thd, fields, select_options, result)))
 	DBUG_RETURN(TRUE);
     thd_proc_info(thd, "init");
-    thd->used_tables=0;                         // Updated by setup_fields
+    thd->lex->used_tables=0;                         // Updated by setup_fields
     err= join->prepare(rref_pointer_array, tables, wild_num,
                        conds, og_num, order, group, having, proc_param,
                        select_lex, unit);
@@ -16949,7 +16949,7 @@ static void select_describe(JOIN *join, bool need_tmp_table, bool need_order,
 	  need_order=0;
 	  extra.append(STRING_WITH_LEN("; Using filesort"));
 	}
-	if (distinct & test_all_bits(used_tables,thd->used_tables))
+	if (distinct & test_all_bits(used_tables, thd->lex->used_tables))
 	  extra.append(STRING_WITH_LEN("; Distinct"));
 
         for (uint part= 0; part < tab->ref.key_parts; part++)