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MDEV-16325 CREATE..SELECT..UNION creates a wrong field type for old varchar

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- Adding Type_handler::traditional_merge_field_type()
- Removing real_type_to_type(), field_merge_type()
- Making Type_handler_var_string to merge as VARCHAR
- Additionally, fixing Field_string::print() to add the "/*old*/"
  comment into the data type for the old VARCHAR.
  This is similar to what MDEV-8267 earlier did for old DECIMAL.
- Adding tests
This commit is contained in:
Alexander Barkov
2018-05-30 15:22:58 +04:00
parent d4da8e7c02
commit 3ceb4a54a1
9 changed files with 228 additions and 64 deletions
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38
sql/sql_type.h
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@ -1021,6 +1021,28 @@ public:
virtual const Name name() const= 0;
virtual enum_field_types field_type() const= 0;
virtual enum_field_types real_field_type() const { return field_type(); }
/**
Type code which is used for merging of traditional data types for result
(for UNION and for hybrid functions such as COALESCE).
Mapping can be done both ways: old->new, new->old, depending
on the particular data type implementation:
- type_handler_var_string (MySQL-4.1 old VARCHAR) is converted to
new VARCHAR before merging.
field_type_merge_rules[][] returns new VARCHAR.
- type_handler_newdate is converted to old DATE before merging.
field_type_merge_rules[][] returns NEWDATE.
- Temporal type_handler_xxx2 (new MySQL-5.6 types) are converted to
corresponding old type codes before merging (e.g. TIME2->TIME).
field_type_merge_rules[][] returns old type codes (e.g. TIME).
Then old types codes are supposed to convert to new type codes somehow,
but they do not. So UNION and COALESCE create old columns.
This is a bug and should be fixed eventually.
*/
virtual enum_field_types traditional_merge_field_type() const
{
DBUG_ASSERT(is_traditional_type());
return field_type();
}
virtual Item_result result_type() const= 0;
virtual Item_result cmp_type() const= 0;
virtual enum_mysql_timestamp_type mysql_timestamp_type() const
@ -3123,6 +3145,10 @@ public:
const Name name() const { return m_name_var_string; }
enum_field_types field_type() const { return MYSQL_TYPE_VAR_STRING; }
enum_field_types real_field_type() const { return MYSQL_TYPE_STRING; }
enum_field_types traditional_merge_field_type() const
{
return MYSQL_TYPE_VARCHAR;
}
const Type_handler *type_handler_for_tmp_table(const Item *item) const
{
return varstring_type_handler(item);
@ -3427,7 +3453,11 @@ class Type_handler_enum: public Type_handler_typelib
public:
virtual ~Type_handler_enum() {}
const Name name() const { return m_name_enum; }
virtual enum_field_types real_field_type() const { return MYSQL_TYPE_ENUM; }
enum_field_types real_field_type() const { return MYSQL_TYPE_ENUM; }
enum_field_types traditional_merge_field_type() const
{
return MYSQL_TYPE_ENUM;
}
uint32 calc_pack_length(uint32 length) const;
Field *make_conversion_table_field(TABLE *, uint metadata,
const Field *target) const;
@ -3455,7 +3485,11 @@ class Type_handler_set: public Type_handler_typelib
public:
virtual ~Type_handler_set() {}
const Name name() const { return m_name_set; }
virtual enum_field_types real_field_type() const { return MYSQL_TYPE_SET; }
enum_field_types real_field_type() const { return MYSQL_TYPE_SET; }
enum_field_types traditional_merge_field_type() const
{
return MYSQL_TYPE_SET;
}
uint32 calc_pack_length(uint32 length) const;
Field *make_conversion_table_field(TABLE *, uint metadata,
const Field *target) const;