Bug#47150 Assertion in Field_long::val_int() on MERGE + TRIGGER + multi-table UPDATE

The bug is not related to MERGE table or TRIGGER. More correct description
would be 'assertion on multi-table UPDATE + NATURAL JOIN + MERGEABLE VIEW'.
On PREPARE stage(see test case) we call mark_common_columns() func which
creates ON condition for NATURAL JOIN and sets appropriate
table read_set bitmaps for fields which are used in ON condition.
On EXECUTE stage mark_common_columns() is not called, we set
necessary read_set bitmaps in setup_conds(). But 'B.f1' field
is already processed and related item alredy fixed before
setup_conds() as updated field and setup_conds can not set
read_set bitmap because of that.
The fix is to set read_set bitmap for appropriate table field even
if Item_direct_view_ref item which represents a refernce to this field
is fixed.

1 files changed, 19 insertions, 2 deletions

diff --git a/sql/item.cc b/sql/item.cc
index 26df3a45971..86e4551e55b 100644
--- a/sql/item.cc
+++ b/sql/item.cc
@@ -6331,9 +6331,26 @@ bool Item_direct_view_ref::fix_fields(THD *thd, Item **reference)
   /* view fild reference must be defined */
   DBUG_ASSERT(*ref);
   /* (*ref)->check_cols() will be made in Item_direct_ref::fix_fields */
-  if (!(*ref)->fixed &&
-      ((*ref)->fix_fields(thd, ref)))
+  if ((*ref)->fixed)
+  {
+    Item *ref_item= (*ref)->real_item();
+    if (ref_item->type() == Item::FIELD_ITEM)
+    {
+      /*
+        In some cases we need to update table read set(see bug#47150).
+        If ref item is FIELD_ITEM and fixed then field and table
+        have proper values. So we can use them for update.
+      */
+      Field *fld= ((Item_field*) ref_item)->field;
+      DBUG_ASSERT(fld && fld->table);
+      if (thd->mark_used_columns == MARK_COLUMNS_READ)
+        bitmap_set_bit(fld->table->read_set, fld->field_index);
+    }
+  }
+  else if (!(*ref)->fixed &&
+           ((*ref)->fix_fields(thd, ref)))
     return TRUE;
+
   return Item_direct_ref::fix_fields(thd, reference);
 }