Bug#46958: Assertion in Diagnostics_area::set_ok_status,

trigger, merge table
            
The problem with break statements is that they have very
local effects. Hence a break statement within the inner loop
of a nested-loops join caused execution to proceed to the
next table even though a serious error occurred. The problem
was fixed by breaking out the inner loop into its own
method. The change empowers all errors to terminate the
execution.
            
The errors that will now halt multi-DELETE execution
altogether are 
  - triggers returning errors
  - handler errors
  - server being killed


mysql-test/r/delete.result:
  Bug#46958: Test result.
mysql-test/t/delete.test:
  Bug#46958: Test case.
sql/sql_class.h:
  Bug#46958: New method declaration.
sql/sql_delete.cc:
  Bug#46958: New method implementation.

1 files changed, 87 insertions, 61 deletions

diff --git a/sql/sql_delete.cc b/sql/sql_delete.cc
index d2f90fa9288..a81a5f4641f 100644
--- a/sql/sql_delete.cc
+++ b/sql/sql_delete.cc
@@ -860,22 +860,19 @@ void multi_delete::abort()
 
 
 
-/*
+/**
   Do delete from other tables.
-  Returns values:
-	0 ok
-	1 error
+
+  @retval 0 ok
+  @retval 1 error
+
+  @todo Is there any reason not use the normal nested-loops join? If not, and
+  there is no documentation supporting it, this method and callee should be
+  removed and there should be hooks within normal execution.
 */
 
 int multi_delete::do_deletes()
 {
-  int local_error= 0, counter= 0, tmp_error;
-  bool will_batch;
-  /*
-    If the IGNORE option is used all non fatal errors will be translated
-    to warnings and we should not break the row-by-row iteration
-  */
-  bool ignore= thd->lex->current_select->no_error;
   DBUG_ENTER("do_deletes");
   DBUG_ASSERT(do_delete);
 
@@ -886,79 +883,108 @@ int multi_delete::do_deletes()
   table_being_deleted= (delete_while_scanning ? delete_tables->next_local :
                         delete_tables);
  
-  for (; table_being_deleted;
+  for (uint counter= 0; table_being_deleted;
        table_being_deleted= table_being_deleted->next_local, counter++)
   { 
-    ha_rows last_deleted= deleted;
     TABLE *table = table_being_deleted->table;
     if (tempfiles[counter]->get(table))
+      DBUG_RETURN(1);
+
+    int local_error= 
+      do_table_deletes(table, thd->lex->current_select->no_error);
+
+    if (thd->killed && !local_error)
+      DBUG_RETURN(1);
+
+    if (local_error == -1)				// End of file
+      local_error = 0;
+
+    if (local_error)
+      DBUG_RETURN(local_error);
+  }
+  DBUG_RETURN(0);
+}
+
+
+/**
+   Implements the inner loop of nested-loops join within multi-DELETE
+   execution.
+
+   @param table The table from which to delete.
+
+   @param ignore If used, all non fatal errors will be translated
+   to warnings and we should not break the row-by-row iteration.
+
+   @return Status code
+
+   @retval  0 All ok.
+   @retval  1 Triggers or handler reported error.
+   @retval -1 End of file from handler.
+*/
+int multi_delete::do_table_deletes(TABLE *table, bool ignore)
+{
+  int local_error= 0;
+  READ_RECORD info;
+  ha_rows last_deleted= deleted;
+  DBUG_ENTER("do_deletes_for_table");
+  init_read_record(&info, thd, table, NULL, 0, 1, FALSE);
+  /*
+    Ignore any rows not found in reference tables as they may already have
+    been deleted by foreign key handling
+  */
+  info.ignore_not_found_rows= 1;
+  bool will_batch= !table->file->start_bulk_delete();
+  while (!(local_error= info.read_record(&info)) && !thd->killed)
+  {
+    if (table->triggers &&
+        table->triggers->process_triggers(thd, TRG_EVENT_DELETE,
+                                          TRG_ACTION_BEFORE, FALSE))
     {
-      local_error=1;
+      local_error= 1;
       break;
     }
-
-    READ_RECORD	info;
-    init_read_record(&info, thd, table, NULL, 0, 1, FALSE);
+      
+    local_error= table->file->ha_delete_row(table->record[0]);
+    if (local_error && !ignore)
+    {
+      table->file->print_error(local_error, MYF(0));
+      break;
+    }
+      
     /*
-      Ignore any rows not found in reference tables as they may already have
-      been deleted by foreign key handling
+      Increase the reported number of deleted rows only if no error occurred
+      during ha_delete_row.
+      Also, don't execute the AFTER trigger if the row operation failed.
     */
-    info.ignore_not_found_rows= 1;
-    will_batch= !table->file->start_bulk_delete();
-    while (!(local_error=info.read_record(&info)) && !thd->killed)
+    if (!local_error)
     {
+      deleted++;
       if (table->triggers &&
           table->triggers->process_triggers(thd, TRG_EVENT_DELETE,
-                                            TRG_ACTION_BEFORE, FALSE))
+                                            TRG_ACTION_AFTER, FALSE))
       {
         local_error= 1;
         break;
       }
-
-      local_error= table->file->ha_delete_row(table->record[0]);
-      if (local_error && !ignore)
-      {
-        table->file->print_error(local_error,MYF(0));
-        break;
-      }
-
-      /*
-        Increase the reported number of deleted rows only if no error occurred
-        during ha_delete_row.
-        Also, don't execute the AFTER trigger if the row operation failed.
-      */
-      if (!local_error)
-      {
-        deleted++;
-        if (table->triggers &&
-            table->triggers->process_triggers(thd, TRG_EVENT_DELETE,
-                                              TRG_ACTION_AFTER, FALSE))
-        {
-          local_error= 1;
-          break;
-        }
-      }
     }
-    if (will_batch && (tmp_error= table->file->end_bulk_delete()))
+  }
+  if (will_batch)
+  {
+    int tmp_error= table->file->end_bulk_delete();
+    if (tmp_error && !local_error)
     {
-      if (!local_error)
-      {
-        local_error= tmp_error;
-        table->file->print_error(local_error,MYF(0));
-      }
+      local_error= tmp_error;
+      table->file->print_error(local_error, MYF(0));
     }
-    if (last_deleted != deleted && !table->file->has_transactions())
-      thd->transaction.stmt.modified_non_trans_table= TRUE;
-    end_read_record(&info);
-    if (thd->killed && !local_error)
-      local_error= 1;
-    if (local_error == -1)				// End of file
-      local_error = 0;
   }
+  if (last_deleted != deleted && !table->file->has_transactions())
+    thd->transaction.stmt.modified_non_trans_table= TRUE;
+
+  end_read_record(&info);
+
   DBUG_RETURN(local_error);
 }
 
-
 /*
   Send ok to the client