MDEV-17362: SIGSEGV in JOIN::optimize_inner or Assertion `fixed == 0' failed in Item_equal::fix_fields, server crashes after 2nd execution of PS

Move reinitialisation of pushdown variables for every query, because it used now not only for derived tables.

mysql-test/main/subselect_innodb.result

@@ -616,3 +616,36 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 Warnings:
 Note	1003	select `test`.`t1`.`f1` AS `f1`,`test`.`t2`.`f2` AS `f2`,`test`.`t3`.`f3` AS `f3` from `test`.`t1` join `test`.`t2` semi join (`test`.`t4`) join `test`.`t3` where `test`.`t4`.`f4` = 1 and `test`.`t1`.`f1` >= `test`.`t2`.`f2`
 DROP TABLE t1,t2,t3,t4;
+# 
+# MDEV-17362: SIGSEGV in JOIN::optimize_inner or Assertion `fixed == 0'
+# failed in  Item_equal::fix_fields, server crashes after 2nd execution
+# of PS
+# 
+create table t1 (a int, b int);
+create table t2 (x int, y int);
+insert into t1 values (1,1),(2,2);
+insert into t2 values (1,1),(2,2),(2,3);
+# here we can see conditions pushdown (see HAVING):
+prepare stmt from "
+explain extended
+SELECT * FROM t1
+WHERE a = b
+      AND (a,b) IN (SELECT t2.x, COUNT(t2.y) FROM t2 WHERE 1=2 GROUP BY t2.x);";
+execute stmt;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	PRIMARY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE noticed after reading const tables
+2	MATERIALIZED	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE
+Warnings:
+Note	1003	/* select#1 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from  <materialize> (/* select#2 */ select `test`.`t2`.`x`,count(`test`.`t2`.`y`) from `test`.`t2` where 0 group by `test`.`t2`.`x` having `COUNT(t2.y)` = `test`.`t2`.`x`) join `test`.`t1` where 0
+# here re-execution of the pushdown does not crash:
+prepare stmt from "
+SELECT * FROM t1
+WHERE a = b
+      AND (a,b) IN (SELECT t2.x, COUNT(t2.y) FROM t2 WHERE 1=2 GROUP BY t2.x);";
+execute stmt;
+a	b
+execute stmt;
+a	b
+execute stmt;
+a	b
+drop table t1,t2;

mysql-test/main/subselect_innodb.test

@@ -611,3 +611,35 @@ FROM t1
 
 DROP TABLE t1,t2,t3,t4;
 
+--echo # 
+--echo # MDEV-17362: SIGSEGV in JOIN::optimize_inner or Assertion `fixed == 0'
+--echo # failed in  Item_equal::fix_fields, server crashes after 2nd execution
+--echo # of PS
+--echo # 
+
+create table t1 (a int, b int);
+create table t2 (x int, y int);
+ 
+insert into t1 values (1,1),(2,2);
+insert into t2 values (1,1),(2,2),(2,3);
+
+--echo # here we can see conditions pushdown (see HAVING):
+prepare stmt from "
+explain extended
+SELECT * FROM t1
+WHERE a = b
+      AND (a,b) IN (SELECT t2.x, COUNT(t2.y) FROM t2 WHERE 1=2 GROUP BY t2.x);";
+
+execute stmt;
+
+--echo # here re-execution of the pushdown does not crash:
+prepare stmt from "
+SELECT * FROM t1
+WHERE a = b
+      AND (a,b) IN (SELECT t2.x, COUNT(t2.y) FROM t2 WHERE 1=2 GROUP BY t2.x);";
+
+execute stmt;
+execute stmt;
+execute stmt;
+
+drop table t1,t2;

sql/sql_derived.cc

@@ -1293,11 +1293,6 @@ bool mysql_derived_reinit(THD *thd, LEX *lex, TABLE_LIST *derived)
   unit->types.empty();
   /* for derived tables & PS (which can't be reset by Item_subselect) */
   unit->reinit_exec_mechanism();
-  for (st_select_lex *sl= unit->first_select(); sl; sl= sl->next_select())
-  {
-    sl->cond_pushed_into_where= NULL;
-    sl->cond_pushed_into_having= NULL;
-  }
   unit->set_thd(thd);
   DBUG_RETURN(FALSE);
 }

sql/sql_prepare.cc

@@ -3026,6 +3026,10 @@ void reinit_stmt_before_use(THD *thd, LEX *lex)
         for (order= win_spec->order_list->first; order; order= order->next)
           order->item= &order->item_ptr;
       }
+
+      // Reinit Pushdown
+      sl->cond_pushed_into_where= NULL;
+      sl->cond_pushed_into_having= NULL;
     }
     if (sl->changed_elements & TOUCHED_SEL_DERIVED)
     {

sql/sql_select.cc

@@ -13463,7 +13463,9 @@ void JOIN::join_free()
 void JOIN::cleanup(bool full)
 {
   DBUG_ENTER("JOIN::cleanup");
-  DBUG_PRINT("enter", ("full %u", (uint) full));
+  DBUG_PRINT("enter", ("select: %d (%p)  join: %p  full: %u",
+                       select_lex->select_number, select_lex, this,
+                       (uint) full));
 
   if (full)
     have_query_plan= QEP_DELETED;