MDEV-29069 follow-up: improve DEFAULT rulesbb-10.11-oalter

previously, fields with DEFAULTs were allowed just when expression is
deterministic. In case of online alter, we should recursively check that
underlying fields of expression also either have explicit values, or
have DEFAULT following this validity rule.

1 files changed, 48 insertions, 11 deletions

diff --git a/sql/log_event_server.cc b/sql/log_event_server.cc
index 9bc06dab7c5..0aa89e1d605 100644
--- a/sql/log_event_server.cc
+++ b/sql/log_event_server.cc
@@ -8024,6 +8024,51 @@ record_compare_exit:
 record_compare_differ:
   return true;
 }
+/**
+  Traverses default item expr of a field, and underlying field's default values.
+  If it is an extra field and has no value replicated, then its default expr
+  should be also checked.
+ */
+class Rpl_key_part_checker: public Field_enumerator
+{
+  bool online_alter;
+  Field *next_number_field;
+  bool field_usable;
+public:
+
+
+  void visit_field(Item_field *item) override
+  {
+    if (!field_usable)
+      return;
+    field_usable= check_field(item->field);
+  }
+
+  bool check_field(Field *f)
+  {
+    if (f->has_explicit_value())
+      return true;
+
+    if ((!f->vcol_info && !online_alter) || f == next_number_field)
+      return false;
+
+    Virtual_column_info *computed= f->vcol_info ? f->vcol_info
+                                   : f->default_value;
+
+    if (computed == NULL)
+      return true; // No DEFAULT, or constant DEFAULT
+
+    // Deterministic DEFAULT or vcol expression
+    return !(computed->flags & VCOL_NOT_STRICTLY_DETERMINISTIC)
+           && !computed->expr->walk(&Item::enumerate_field_refs_processor,
+                                    false, this)
+           && field_usable;
+  }
+
+  Rpl_key_part_checker(bool online_alter, Field *next_number_field):
+    online_alter(online_alter), next_number_field(next_number_field),
+    field_usable(true) {}
+};
 
 
 /**
@@ -8054,19 +8099,11 @@ uint Rows_log_event::find_key_parts(const KEY *key) const
     }
   }
 
+  Rpl_key_part_checker key_part_checker(online_alter,
+                                        m_table->found_next_number_field);
   for (p= 0; p < key->user_defined_key_parts; p++)
   {
-    Field *f= key->key_part[p].field;
-    /*
-      in the online alter case (but not in replication) we don't have
-      to reject an index if it includes new columns, as long as
-      their values are deterministic.
-    */
-    bool non_deterministic_default= f->default_value &&
-                     f->default_value->flags & VCOL_NOT_STRICTLY_DETERMINISTIC;
-    bool next_number_field= f == f->table->next_number_field;
-    if (!bitmap_is_set(&m_table->has_value_set, f->field_index) &&
-        (!online_alter || non_deterministic_default || next_number_field))
+    if (!key_part_checker.check_field(key->key_part[p].field))
       break;
   }
   return p;