MDEV-6849 ON UPDATE CURRENT_TIMESTAMP doesn't always work

reset default fields not for every modified row, but only once,
at the beginning, as the set of modified fields doesn't change.

exception: INSERT ... ON DUPLICATE KEY UPDATE - the set of fields
does change per row and in that case we reset default fields per row.

1 files changed, 1 insertions, 0 deletions

diff --git a/sql/table.h b/sql/table.h
index 8e31c0e2600..58b78af6836 100644
--- a/sql/table.h
+++ b/sql/table.h
@@ -1377,6 +1377,7 @@ public:
   uint actual_n_key_parts(KEY *keyinfo);
   ulong actual_key_flags(KEY *keyinfo);
   int update_default_fields();
+  void reset_default_fields();
   inline ha_rows stat_records() { return used_stat_records; }
 
   void prepare_triggers_for_insert_stmt_or_event();