mariadb/storage/myisammrg/ha_myisammrg.h
V Narayanan 0d61bd9dce Bug#45800 crash when replacing into a merge table and there is a duplicate
A REPLACE in the MERGE engine is actually a REPLACE
into one (FIRST or LAST) of the underlying MyISAM
tables. So in effect the server works on the meta
data of the MERGE table, while the real insert happens
in the MyISAM table.

The MERGE table has no index, while MyISAM has a
unique index. When a REPLACE into a MERGE table (
and the REPLACE conflicts with a duplicate in a
child table) is done, we try to access the duplicate
key information for the MERGE table. This information
actually does not exist, hence this results in a crash.

The problem can be resolved by modifying the MERGE
engine to provide us the duplicate key information
directly, instead of just returning the MyISAM index
number as the error key. Then the SQL layer (or "the
server") does not try to access the key_info of the
MERGE table, which does not exist.

The current patch modifies the MERGE engine to provide
the position for a record where a unique key violation
occurs.

include/myisammrg.h:
  Bug#45800 crash when replacing into a merge table and there is a duplicate
  
  Add a member to the st_mymerge_info structure that will
  store the duplicate key offset in the MERGE table. This
  offset will be the sum of the record offset of the MyISAM
  table within the MERGE table and the offset of the record
  within the MyISAM table.
mysql-test/r/merge.result:
  Bug#45800 crash when replacing into a merge table and there is a duplicate
  
  Result file for the test case.
mysql-test/t/merge.test:
  Bug#45800 crash when replacing into a merge table and there is a duplicate
  
  Added test case for both REPLACE and INSERT...ON DUPLICATE UPDATE.
storage/myisammrg/ha_myisammrg.cc:
  Bug#45800 crash when replacing into a merge table and there is a duplicate
  
  The info method now will process the HA_STATUS_ERRKEY flag
  and will return the index and the offset of the duplicate
  key.
storage/myisammrg/ha_myisammrg.h:
  Bug#45800 crash when replacing into a merge table and there is a duplicate
  
  Set the HA_DUPLICATE_POS flag to indicate that the duplicate
  key information is now available in the MERGE storage engine.
storage/myisammrg/myrg_info.c:
  Bug#45800 crash when replacing into a merge table and there is a duplicate
  
  We modify the myrg_status function to return the position of the
  duplicate key. The duplicate key position in the MERGE table will
  be the MyISAM file_offset and the offset within the MyISAM table
  of the start position of the records.
2009-07-30 16:04:41 +05:30

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/* Copyright (C) 2000-2006 MySQL AB
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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
#ifdef USE_PRAGMA_INTERFACE
#pragma interface /* gcc class implementation */
#endif
/* class for the the myisam merge handler */
#include <myisammrg.h>
class ha_myisammrg: public handler
{
MYRG_INFO *file;
my_bool is_cloned; /* This instance has been cloned */
public:
TABLE_LIST *next_child_attach; /* next child to attach */
uint test_if_locked; /* flags from ::open() */
bool need_compat_check; /* if need compatibility check */
ha_myisammrg(handlerton *hton, TABLE_SHARE *table_arg);
~ha_myisammrg();
const char *table_type() const { return "MRG_MyISAM"; }
const char **bas_ext() const;
const char *index_type(uint key_number);
ulonglong table_flags() const
{
return (HA_REC_NOT_IN_SEQ | HA_AUTO_PART_KEY | HA_NO_TRANSACTIONS |
HA_BINLOG_ROW_CAPABLE | HA_BINLOG_STMT_CAPABLE |
HA_NULL_IN_KEY | HA_CAN_INDEX_BLOBS | HA_FILE_BASED |
HA_ANY_INDEX_MAY_BE_UNIQUE | HA_CAN_BIT_FIELD |
HA_HAS_RECORDS |
HA_NO_COPY_ON_ALTER |
HA_DUPLICATE_POS);
}
ulong index_flags(uint inx, uint part, bool all_parts) const
{
return ((table_share->key_info[inx].algorithm == HA_KEY_ALG_FULLTEXT) ?
0 : HA_READ_NEXT | HA_READ_PREV | HA_READ_RANGE |
HA_READ_ORDER | HA_KEYREAD_ONLY);
}
uint max_supported_keys() const { return MI_MAX_KEY; }
uint max_supported_key_length() const { return MI_MAX_KEY_LENGTH; }
uint max_supported_key_part_length() const { return MI_MAX_KEY_LENGTH; }
double scan_time()
{ return ulonglong2double(stats.data_file_length) / IO_SIZE + file->tables; }
int open(const char *name, int mode, uint test_if_locked);
int attach_children(void);
int detach_children(void);
virtual handler *clone(MEM_ROOT *mem_root);
int close(void);
int write_row(uchar * buf);
int update_row(const uchar * old_data, uchar * new_data);
int delete_row(const uchar * buf);
int index_read_map(uchar *buf, const uchar *key, key_part_map keypart_map,
enum ha_rkey_function find_flag);
int index_read_idx_map(uchar *buf, uint index, const uchar *key,
key_part_map keypart_map,
enum ha_rkey_function find_flag);
int index_read_last_map(uchar *buf, const uchar *key, key_part_map keypart_map);
int index_next(uchar * buf);
int index_prev(uchar * buf);
int index_first(uchar * buf);
int index_last(uchar * buf);
int index_next_same(uchar *buf, const uchar *key, uint keylen);
int rnd_init(bool scan);
int rnd_next(uchar *buf);
int rnd_pos(uchar * buf, uchar *pos);
void position(const uchar *record);
ha_rows records_in_range(uint inx, key_range *min_key, key_range *max_key);
int info(uint);
int reset(void);
int extra(enum ha_extra_function operation);
int extra_opt(enum ha_extra_function operation, ulong cache_size);
int external_lock(THD *thd, int lock_type);
uint lock_count(void) const;
int create(const char *name, TABLE *form, HA_CREATE_INFO *create_info);
THR_LOCK_DATA **store_lock(THD *thd, THR_LOCK_DATA **to,
enum thr_lock_type lock_type);
void update_create_info(HA_CREATE_INFO *create_info);
void append_create_info(String *packet);
MYRG_INFO *myrg_info() { return file; }
TABLE *table_ptr() { return table; }
bool check_if_incompatible_data(HA_CREATE_INFO *info, uint table_changes);
int check(THD* thd, HA_CHECK_OPT* check_opt);
ha_rows records();
};