diff options
Diffstat (limited to 'sql/item.cc')
| -rw-r--r-- | sql/item.cc | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/sql/item.cc b/sql/item.cc index 95ff5462fad..27cb6d49fd4 100644 --- a/sql/item.cc +++ b/sql/item.cc @@ -6061,14 +6061,13 @@ bool Item_type_holder::join_types(THD *thd, Item *item) max_length= my_decimal_precision_to_length(precision, decimals, unsigned_flag); } - else - max_length= max(max_length, display_length(item)); - + switch (Field::result_merge_type(fld_type)) { case STRING_RESULT: { const char *old_cs, *old_derivation; + uint32 old_max_chars= max_length / collation.collation->mbmaxlen; old_cs= collation.collation->name; old_derivation= collation.derivation_name(); if (collation.aggregate(item->collation, MY_COLL_ALLOW_CONV)) @@ -6080,6 +6079,14 @@ bool Item_type_holder::join_types(THD *thd, Item *item) "UNION"); DBUG_RETURN(TRUE); } + /* + To figure out max_length, we have to take into account possible + expansion of the size of the values because of character set + conversions. + */ + max_length= max(old_max_chars * collation.collation->mbmaxlen, + display_length(item) / item->collation.collation->mbmaxlen * + collation.collation->mbmaxlen); break; } case REAL_RESULT: @@ -6098,7 +6105,8 @@ bool Item_type_holder::join_types(THD *thd, Item *item) max_length= (fld_type == MYSQL_TYPE_FLOAT) ? FLT_DIG+6 : DBL_DIG+7; break; } - default:; + default: + max_length= max(max_length, display_length(item)); }; maybe_null|= item->maybe_null; get_full_info(item); |