MDEV-16823 Add Type_handler::Column_definition_reuse_fix_attributes()

Adding new methods:

- virtual void Type_handler::Column_definition_reuse_fix_attributes()
  according to the MDEV description

- virtual uint32 Field::character_octet_length()
  To simplify handling of Column_definition::length for
  TEXT and VARCHAR columns (with and without compression).

sql/field.cc

@@ -10653,7 +10653,7 @@ bool Field_vers_trx_id::test_if_equality_guarantees_uniqueness(const Item* item)
 
 
 Column_definition_attributes::Column_definition_attributes(const Field *field)
- :length(field->field_length),
+ :length(field->character_octet_length() / field->charset()->mbmaxlen),
   unireg_check(field->unireg_check),
   interval(NULL),
   charset(field->charset()), // May be NULL ptr
@@ -10682,6 +10682,8 @@ Column_definition::Column_definition(THD *thd, Field *old_field,
   compression_method_ptr= 0;
   versioning= VERSIONING_NOT_SET;
   invisible= old_field->invisible;
+  interval_list.empty(); // prepare_interval_field() needs this
+  char_length= (uint) length;
 
   if (orig_field)
   {
@@ -10699,61 +10701,7 @@ Column_definition::Column_definition(THD *thd, Field *old_field,
     check_constraint= 0;
   }
 
-  switch (real_field_type()) {
-  case MYSQL_TYPE_TINY_BLOB:
-  case MYSQL_TYPE_BLOB:
-  case MYSQL_TYPE_MEDIUM_BLOB:
-  case MYSQL_TYPE_LONG_BLOB:
-    length/= charset->mbmaxlen;
-    key_length/= charset->mbmaxlen;
-    break;
-  case MYSQL_TYPE_STRING:
-  case MYSQL_TYPE_ENUM:
-  case MYSQL_TYPE_SET:
-  case MYSQL_TYPE_VARCHAR:
-  case MYSQL_TYPE_VAR_STRING:
-    /* This is corrected in create_length_to_internal_length */
-    length= (length+charset->mbmaxlen-1) / charset->mbmaxlen -
-            MY_TEST(old_field->compression_method());
-    break;
-#ifdef HAVE_SPATIAL
-  case MYSQL_TYPE_GEOMETRY:
-    geom_type= ((Field_geom*)old_field)->geom_type;
-    srid= ((Field_geom*)old_field)->srid;
-    break;
-#endif
-  case MYSQL_TYPE_YEAR:
-    if (length != 4)
-    {
-      char buff[sizeof("YEAR()") + MY_INT64_NUM_DECIMAL_DIGITS + 1];
-      my_snprintf(buff, sizeof(buff), "YEAR(%llu)", length);
-      push_warning_printf(thd, Sql_condition::WARN_LEVEL_NOTE,
-                          ER_WARN_DEPRECATED_SYNTAX,
-                          ER_THD(thd, ER_WARN_DEPRECATED_SYNTAX),
-                          buff, "YEAR(4)");
-    }
-    break;
-  case MYSQL_TYPE_FLOAT:
-  case MYSQL_TYPE_DOUBLE:
-    /*
-      Floating points are stored with FLOATING_POINT_DECIMALS but internally
-      in MariaDB used with NOT_FIXED_DEC, which is >= FLOATING_POINT_DECIMALS.
-    */
-    if (decimals >= FLOATING_POINT_DECIMALS)
-      decimals= NOT_FIXED_DEC;
-    break;
-  default:
-    break;
-  }
-
-  if (flags & (ENUM_FLAG | SET_FLAG))
-    interval= ((Field_enum*) old_field)->typelib;
-  else
-    interval=0;
-
-  interval_list.empty(); // prepare_interval_field() needs this
-
-  char_length= (uint)length;
+  type_handler()->Column_definition_reuse_fix_attributes(thd, this, old_field);
 
   type_handler()->Column_definition_implicit_upgrade(this);
 
@@ -10837,11 +10785,11 @@ Column_definition::redefine_stage1_common(const Column_definition *dup_field,
 
 uint32 Field_blob::char_length() const
 {
-  return Field_blob::octet_length();
+  return Field_blob::character_octet_length();
 }
 
 
-uint32 Field_blob::octet_length() const
+uint32 Field_blob::character_octet_length() const
 {
   switch (packlength)
   {

sql/field.h

@@ -1484,12 +1484,21 @@ public:
   /* convert decimal to longlong with overflow check */
   longlong convert_decimal2longlong(const my_decimal *val, bool unsigned_flag,
                                     int *err);
+  /*
+    Maximum number of bytes in character representation.
+    - For string types it is equal to the field capacity, in bytes.
+    - For non-string types it represents the longest possible string length
+      after conversion to string.
+  */
+  virtual uint32 character_octet_length() const
+  {
+    return field_length;
+  }
   /* The max. number of characters */
   virtual uint32 char_length() const
   {
     return field_length / charset()->mbmaxlen;
   }
-
   virtual geometry_type get_geometry_type()
   {
     /* shouldn't get here. */
@@ -1812,6 +1821,7 @@ public:
   enum Derivation derivation(void) const { return field_derivation; }
   bool binary() const { return field_charset == &my_charset_bin; }
   uint32 max_display_length() const { return field_length; }
+  uint32 character_octet_length() const { return field_length; }
   uint32 char_length() const { return field_length / field_charset->mbmaxlen; }
   Information_schema_character_attributes
     information_schema_character_attributes() const
@@ -3571,6 +3581,7 @@ private:
     str.append(STRING_WITH_LEN(" /*!100301 COMPRESSED*/"));
   }
   uint32 max_display_length() const { return field_length - 1; }
+  uint32 character_octet_length() const { return field_length - 1; }
   uint32 char_length() const
   {
     return (field_length - 1) / field_charset->mbmaxlen;
@@ -3703,7 +3714,7 @@ public:
   Information_schema_character_attributes
     information_schema_character_attributes() const
   {
-    uint32 octets= Field_blob::octet_length();
+    uint32 octets= Field_blob::character_octet_length();
     uint32 chars= octets / field_charset->mbminlen;
     return Information_schema_character_attributes(octets, chars);
   }
@@ -3869,7 +3880,7 @@ public:
   { return charset() == &my_charset_bin ? FALSE : TRUE; }
   uint32 max_display_length() const;
   uint32 char_length() const;
-  uint32 octet_length() const;
+  uint32 character_octet_length() const;
   uint is_equal(Create_field *new_field);
 
   friend void TABLE::remember_blob_values(String *blob_storage);

sql/sql_type.cc

@@ -1640,6 +1640,70 @@ bool Type_handler_bit::
   return def->fix_attributes_bit();
 }
 
+/*************************************************************************/
+
+void Type_handler_blob_common::
+       Column_definition_reuse_fix_attributes(THD *thd,
+                                              Column_definition *def,
+                                              const Field *field) const
+{
+  DBUG_ASSERT(def->key_length == 0);
+}
+
+
+void Type_handler_typelib::
+       Column_definition_reuse_fix_attributes(THD *thd,
+                                              Column_definition *def,
+                                              const Field *field) const
+{
+  DBUG_ASSERT(def->flags & (ENUM_FLAG | SET_FLAG));
+  def->interval= field->get_typelib();
+}
+
+
+#ifdef HAVE_SPATIAL
+void Type_handler_geometry::
+       Column_definition_reuse_fix_attributes(THD *thd,
+                                              Column_definition *def,
+                                              const Field *field) const
+{
+  def->geom_type= ((Field_geom*) field)->geom_type;
+  def->srid= ((Field_geom*) field)->srid;
+}
+#endif
+
+
+void Type_handler_year::
+       Column_definition_reuse_fix_attributes(THD *thd,
+                                              Column_definition *def,
+                                              const Field *field) const
+{
+  if (def->length != 4)
+  {
+    char buff[sizeof("YEAR()") + MY_INT64_NUM_DECIMAL_DIGITS + 1];
+    my_snprintf(buff, sizeof(buff), "YEAR(%llu)", def->length);
+    push_warning_printf(thd, Sql_condition::WARN_LEVEL_NOTE,
+                        ER_WARN_DEPRECATED_SYNTAX,
+                        ER_THD(thd, ER_WARN_DEPRECATED_SYNTAX),
+                        buff, "YEAR(4)");
+  }
+}
+
+
+void Type_handler_real_result::
+       Column_definition_reuse_fix_attributes(THD *thd,
+                                              Column_definition *def,
+                                              const Field *field) const
+{
+  /*
+    Floating points are stored with FLOATING_POINT_DECIMALS but internally
+    in MariaDB used with NOT_FIXED_DEC, which is >= FLOATING_POINT_DECIMALS.
+  */
+  if (def->decimals >= FLOATING_POINT_DECIMALS)
+    def->decimals= NOT_FIXED_DEC;
+}
+
+
 /*************************************************************************/
 
 bool Type_handler::

sql/sql_type.h

@@ -1275,7 +1275,17 @@ public:
   // Automatic upgrade, e.g. for ALTER TABLE t1 FORCE
   virtual void Column_definition_implicit_upgrade(Column_definition *c) const
   { }
+  // Fix attributes after the parser
   virtual bool Column_definition_fix_attributes(Column_definition *c) const= 0;
+  /*
+    Fix attributes from an existing field. Used for:
+    - ALTER TABLE (for columns that do not change)
+    - DECLARE var TYPE OF t1.col1; (anchored SP variables)
+  */
+  virtual void Column_definition_reuse_fix_attributes(THD *thd,
+                                                      Column_definition *c,
+                                                      const Field *field) const
+  { }
   virtual bool Column_definition_prepare_stage1(THD *thd,
                                                 MEM_ROOT *mem_root,
                                                 Column_definition *c,
@@ -1630,6 +1640,12 @@ public:
   {
     return false;
   }
+  void Column_definition_reuse_fix_attributes(THD *thd,
+                                              Column_definition *c,
+                                              const Field *field) const
+  {
+    DBUG_ASSERT(0);
+  }
   bool Column_definition_prepare_stage1(THD *thd,
                                         MEM_ROOT *mem_root,
                                         Column_definition *c,
@@ -1934,6 +1950,9 @@ public:
   Item_result cmp_type() const { return REAL_RESULT; }
   virtual ~Type_handler_real_result() {}
   const Type_handler *type_handler_for_comparison() const;
+  void Column_definition_reuse_fix_attributes(THD *thd,
+                                              Column_definition *c,
+                                              const Field *field) const;
   int stored_field_cmp_to_item(THD *thd, Field *field, Item *item) const;
   bool subquery_type_allows_materialization(const Item *inner,
                                             const Item *outer) const;
@@ -2766,6 +2785,9 @@ public:
   Field *make_conversion_table_field(TABLE *, uint metadata,
                                      const Field *target) const;
   bool Column_definition_fix_attributes(Column_definition *c) const;
+  void Column_definition_reuse_fix_attributes(THD *thd,
+                                              Column_definition *c,
+                                              const Field *field) const;
   bool Column_definition_prepare_stage2(Column_definition *c,
                                         handler *file,
                                         ulonglong table_flags) const
@@ -3605,6 +3627,9 @@ public:
   }
   bool is_param_long_data_type() const { return true; }
   bool Column_definition_fix_attributes(Column_definition *c) const;
+  void Column_definition_reuse_fix_attributes(THD *thd,
+                                              Column_definition *c,
+                                              const Field *field) const;
   bool Column_definition_prepare_stage2(Column_definition *c,
                                         handler *file,
                                         ulonglong table_flags) const;
@@ -3732,6 +3757,9 @@ public:
                                           const uchar *buffer,
                                           LEX_CUSTRING *gis_options) const;
   bool Column_definition_fix_attributes(Column_definition *c) const;
+  void Column_definition_reuse_fix_attributes(THD *thd,
+                                              Column_definition *c,
+                                              const Field *field) const;
   bool Column_definition_prepare_stage1(THD *thd,
                                         MEM_ROOT *mem_root,
                                         Column_definition *c,
@@ -3802,6 +3830,9 @@ public:
                                        Type_handler_hybrid_field_type *,
                                        Type_all_attributes *atrr,
                                        Item **items, uint nitems) const;
+  void Column_definition_reuse_fix_attributes(THD *thd,
+                                              Column_definition *c,
+                                              const Field *field) const;
   bool Column_definition_prepare_stage1(THD *thd,
                                         MEM_ROOT *mem_root,
                                         Column_definition *c,