MDEV-16765: Missing rows with pushdown condition defined with CASE using Item_cond

The bug appears because of the wrong pushdown into the WHERE clause of the
materialized derived table/view work. For the excl_dep_on_grouping_fields()
method that checks if the condition can be pushed into the WHERE clause
the case when Item_cond is used is missing. For Item_cond elements this
method always returns positive result (that condition can be pushed).
So this condition is pushed even if is shouldn't be pushed.

To fix it new Item_cond::excl_dep_on_grouping_fields() method is added.

1 files changed, 13 insertions, 0 deletions

diff --git a/sql/item_cmpfunc.cc b/sql/item_cmpfunc.cc
index f176a0a8193..6834820c0b5 100644
--- a/sql/item_cmpfunc.cc
+++ b/sql/item_cmpfunc.cc
@@ -4970,6 +4970,19 @@ Item *Item_cond::build_clone(THD *thd, MEM_ROOT *mem_root)
 }
 
 
+bool Item_cond::excl_dep_on_grouping_fields(st_select_lex *sel)
+{
+  List_iterator_fast<Item> li(list);
+  Item *item;
+  while ((item= li++))
+  {
+    if (!item->excl_dep_on_grouping_fields(sel))
+      return false;
+  }
+  return true;
+}
+
+
 void Item_cond_and::mark_as_condition_AND_part(TABLE_LIST *embedding)
 {
   List_iterator<Item> li(list);