1
0
mirror of https://github.com/MariaDB/server.git synced 2025-08-26 01:44:06 +03:00
Files
mariadb/storage/heap/ha_heap.h
Davi Arnaut 5f911fa874 Bug#49938: Failing assertion: inode or deadlock in fsp/fsp0fsp.c
Bug#54678: InnoDB, TRUNCATE, ALTER, I_S SELECT, crash or deadlock

- Incompatible change: truncate no longer resorts to a row by
row delete if the storage engine does not support the truncate
method. Consequently, the count of affected rows does not, in
any case, reflect the actual number of rows.

- Incompatible change: it is no longer possible to truncate a
table that participates as a parent in a foreign key constraint,
unless it is a self-referencing constraint (both parent and child
are in the same table). To work around this incompatible change
and still be able to truncate such tables, disable foreign checks
with SET foreign_key_checks=0 before truncate. Alternatively, if
foreign key checks are necessary, please use a DELETE statement
without a WHERE condition.

Problem description:

The problem was that for storage engines that do not support
truncate table via a external drop and recreate, such as InnoDB
which implements truncate via a internal drop and recreate, the
delete_all_rows method could be invoked with a shared metadata
lock, causing problems if the engine needed exclusive access
to some internal metadata. This problem originated with the
fact that there is no truncate specific handler method, which
ended up leading to a abuse of the delete_all_rows method that
is primarily used for delete operations without a condition.

Solution:

The solution is to introduce a truncate handler method that is
invoked when the engine does not support truncation via a table
drop and recreate. This method is invoked under a exclusive
metadata lock, so that there is only a single instance of the
table when the method is invoked.

Also, the method is not invoked and a error is thrown if
the table is a parent in a non-self-referencing foreign key
relationship. This was necessary to avoid inconsistency as
some integrity checks are bypassed. This is inline with the
fact that truncate is primarily a DDL operation that was
designed to quickly remove all data from a table.
2010-10-06 11:34:28 -03:00

124 lines
4.7 KiB
C++

/* 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 heap handler */
#include <heap.h>
#include "sql_class.h" /* THD */
class ha_heap: public handler
{
HP_INFO *file;
HP_SHARE *internal_share;
key_map btree_keys;
/* number of records changed since last statistics update */
uint records_changed;
uint key_stat_version;
my_bool internal_table;
public:
ha_heap(handlerton *hton, TABLE_SHARE *table);
~ha_heap() {}
handler *clone(MEM_ROOT *mem_root);
const char *table_type() const
{
return (table->in_use->variables.sql_mode & MODE_MYSQL323) ?
"HEAP" : "MEMORY";
}
const char *index_type(uint inx)
{
return ((table_share->key_info[inx].algorithm == HA_KEY_ALG_BTREE) ?
"BTREE" : "HASH");
}
/* Rows also use a fixed-size format */
enum row_type get_row_type() const { return ROW_TYPE_FIXED; }
const char **bas_ext() const;
ulonglong table_flags() const
{
return (HA_FAST_KEY_READ | HA_NO_BLOBS | HA_NULL_IN_KEY |
HA_BINLOG_ROW_CAPABLE | HA_BINLOG_STMT_CAPABLE |
HA_REC_NOT_IN_SEQ | HA_CAN_INSERT_DELAYED | HA_NO_TRANSACTIONS |
HA_HAS_RECORDS | HA_STATS_RECORDS_IS_EXACT);
}
ulong index_flags(uint inx, uint part, bool all_parts) const
{
return ((table_share->key_info[inx].algorithm == HA_KEY_ALG_BTREE) ?
HA_READ_NEXT | HA_READ_PREV | HA_READ_ORDER | HA_READ_RANGE :
HA_ONLY_WHOLE_INDEX | HA_KEY_SCAN_NOT_ROR);
}
const key_map *keys_to_use_for_scanning() { return &btree_keys; }
uint max_supported_keys() const { return MAX_KEY; }
uint max_supported_key_part_length() const { return MAX_KEY_LENGTH; }
double scan_time()
{ return (double) (stats.records+stats.deleted) / 20.0+10; }
double read_time(uint index, uint ranges, ha_rows rows)
{ return (double) rows / 20.0+1; }
int open(const char *name, int mode, uint test_if_locked);
int close(void);
void set_keys_for_scanning(void);
int write_row(uchar * buf);
int update_row(const uchar * old_data, uchar * new_data);
int delete_row(const uchar * buf);
virtual void get_auto_increment(ulonglong offset, ulonglong increment,
ulonglong nb_desired_values,
ulonglong *first_value,
ulonglong *nb_reserved_values);
int index_read_map(uchar * buf, 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_read_idx_map(uchar * buf, uint index, const uchar * key,
key_part_map keypart_map,
enum ha_rkey_function find_flag);
int index_next(uchar * buf);
int index_prev(uchar * buf);
int index_first(uchar * buf);
int index_last(uchar * buf);
int rnd_init(bool scan);
int rnd_next(uchar *buf);
int rnd_pos(uchar * buf, uchar *pos);
void position(const uchar *record);
int info(uint);
int extra(enum ha_extra_function operation);
int reset();
int external_lock(THD *thd, int lock_type);
int delete_all_rows(void);
int truncate();
int reset_auto_increment(ulonglong value);
int disable_indexes(uint mode);
int enable_indexes(uint mode);
int indexes_are_disabled(void);
ha_rows records_in_range(uint inx, key_range *min_key, key_range *max_key);
int delete_table(const char *from);
void drop_table(const char *name);
int rename_table(const char * from, const char * to);
int create(const char *name, TABLE *form, HA_CREATE_INFO *create_info);
void update_create_info(HA_CREATE_INFO *create_info);
THR_LOCK_DATA **store_lock(THD *thd, THR_LOCK_DATA **to,
enum thr_lock_type lock_type);
int cmp_ref(const uchar *ref1, const uchar *ref2)
{
return memcmp(ref1, ref2, sizeof(HEAP_PTR));
}
bool check_if_incompatible_data(HA_CREATE_INFO *info, uint table_changes);
private:
void update_key_stats();
};