mariadb/sql/sql_insert.h
Sergei Golubchik f73bdb685d bugfix: UPDATE and virtual BLOBs
When updating a table with virtual BLOB columns, the following might happen:
- an old record is read from the table, it has no virtual blob values
- update_virtual_fields() is run, vcol blob gets its value into the
  record. But only a pointer to the value is in the table->record[0],
  the value is in Field_blob::value String (but it doesn't have to be!
  it can be in the record, if the column is just a copy of another
  columns: ... b VARCHAR, c BLOB AS (b) ...)
- store_record(table,record[1]), old record now is in record[1]
- fill_record() prepares new values in record[0], vcol blob is updated,
  new value replaces the old one in the Field_blob::value
- now both record[1] and record[0] have a pointer that points to the
  *new* vcol blob value. Or record[1] has a pointer to nowhere if
  Field_blob::value had to realloc.

To resolve this we unlink vcol blobs from the pointer to the
data (in the record[1]). Because the value is not *always* in
the Field_blob::value String, we need to remember what blobs
were unlinked. The orphan memory must be freed manually.

To complicate the matter, ha_update_row() is also used in
multi-update, in REPLACE, in INSERT ... ON DUPLICATE KEY UPDATE,
also on REPLACE ... SELECT, REPLACE DELAYED, and LOAD DATA REPLACE, etc
2016-12-12 20:27:38 +01:00

47 lines
2.1 KiB
C

/* Copyright (c) 2006, 2010, Oracle and/or its affiliates. All rights reserved.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
#ifndef SQL_INSERT_INCLUDED
#define SQL_INSERT_INCLUDED
#include "sql_class.h" /* enum_duplicates */
#include "sql_list.h"
/* Instead of including sql_lex.h we add this typedef here */
typedef List<Item> List_item;
bool mysql_prepare_insert(THD *thd, TABLE_LIST *table_list, TABLE *table,
List<Item> &fields, List_item *values,
List<Item> &update_fields,
List<Item> &update_values, enum_duplicates duplic,
COND **where, bool select_insert,
bool check_fields, bool abort_on_warning);
bool mysql_insert(THD *thd,TABLE_LIST *table,List<Item> &fields,
List<List_item> &values, List<Item> &update_fields,
List<Item> &update_values, enum_duplicates flag,
bool ignore);
void upgrade_lock_type_for_insert(THD *thd, thr_lock_type *lock_type,
enum_duplicates duplic,
bool is_multi_insert);
int check_that_all_fields_are_given_values(THD *thd, TABLE *entry,
TABLE_LIST *table_list);
int write_record(THD *thd, TABLE *table, COPY_INFO *info);
void kill_delayed_threads(void);
#ifdef EMBEDDED_LIBRARY
inline void kill_delayed_threads(void) {}
#endif
#endif /* SQL_INSERT_INCLUDED */