Proper fix for disabling warnings in read_statistics_for_table().

MDEV-20589: Server still crashes in Field::set_warning_truncated_wrong_value

- Use dbug_tmp_use_all_columns() to mark that all fields can be used
- Remove field->is_stat_field (not needed)
- Remove extra arguments to Field::clone() that should not be there
- Safety fix for Field::set_warning_truncated_wrong_value() to not crash
  if table is zero in production builds (We have got crashes several times
  here so better to be safe than sorry).
- Threat wrong character string warnings identical to other field
  conversion warnings. This removes some warnings we before got from
  internal conversion errors.  There is no good reason why a user would
  get an error in case of 'key_field='wrong-utf8-string' but not for
  'field=wrong-utf8-string'.  The old code could also easily give
  thousands of no-sence warnings for one single statement.

1 files changed, 9 insertions, 2 deletions

diff --git a/sql/sql_statistics.cc b/sql/sql_statistics.cc
index 8d1342773f7..5e0275fa65d 100644
--- a/sql/sql_statistics.cc
+++ b/sql/sql_statistics.cc
@@ -1042,7 +1042,9 @@ public:
   {
     char buff[MAX_FIELD_WIDTH];
     String val(buff, sizeof(buff), &my_charset_bin);
+    my_bitmap_map *old_map;
 
+    old_map= dbug_tmp_use_all_columns(stat_table, stat_table->read_set);
     for (uint i= COLUMN_STAT_MIN_VALUE; i <= COLUMN_STAT_HISTOGRAM; i++)
     {  
       Field *stat_field= stat_table->field[i];
@@ -1100,6 +1102,7 @@ public:
         }
       }
     }
+    dbug_tmp_restore_column_map(stat_table->read_set, old_map);
   }
 
 
@@ -1973,7 +1976,7 @@ void create_min_max_statistical_fields_for_table(TABLE *table)
         my_ptrdiff_t diff= record-table->record[0];
         if (!bitmap_is_set(table->read_set, table_field->field_index))
           continue; 
-        if (!(fld= table_field->clone(&table->mem_root, table, diff, TRUE)))
+        if (!(fld= table_field->clone(&table->mem_root, table, diff)))
           continue;
         if (i == 0)
           table_field->collected_stats->min_value= fld;
@@ -2984,9 +2987,12 @@ int read_statistics_for_table(THD *thd, TABLE *table, TABLE_LIST *stat_tables)
   KEY *key_info, *key_info_end;
   TABLE_SHARE *table_share= table->s;
   Table_statistics *read_stats= table_share->stats_cb.table_stats;
-
+  enum_check_fields old_check_level= thd->count_cuted_fields;
   DBUG_ENTER("read_statistics_for_table");
 
+  /* Don't write warnings for internal field conversions */
+  thd->count_cuted_fields= CHECK_FIELD_IGNORE;
+
   /* Read statistics from the statistical table table_stats */
   stat_table= stat_tables[TABLE_STAT].table;
   Table_stat table_stat(stat_table, table);
@@ -3067,6 +3073,7 @@ int read_statistics_for_table(THD *thd, TABLE *table, TABLE_LIST *stat_tables)
   }
 
   table->stats_is_read= TRUE;
+  thd->count_cuted_fields= old_check_level;
 
   DBUG_RETURN(0);
 }