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mariadb/storage/myisam/ha_myisam.h
Davi Arnaut a5efb91dea 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.

mysql-test/suite/innodb/t/innodb-truncate.test:
  Add test cases for truncate and foreign key checks.
  Also test that InnoDB resets auto-increment on truncate.
mysql-test/suite/innodb/t/innodb.test:
  FK is not necessary, test is related to auto-increment.
  
  Update error number, truncate is no longer invoked if
  table is parent in a FK relationship.
mysql-test/suite/innodb/t/innodb_mysql.test:
  Update error number, truncate is no longer invoked if
  table is parent in a FK relationship.
  
  Use delete instead of truncate, test is used to check
  the interaction of FKs, triggers and delete.
mysql-test/suite/parts/inc/partition_check.inc:
  Fix typo.
mysql-test/suite/sys_vars/t/foreign_key_checks_func.test:
  Update error number, truncate is no longer invoked if
  table is parent in a FK relationship.
mysql-test/t/mdl_sync.test:
  Modify test case to reflect and ensure that truncate takes
  a exclusive metadata lock.
mysql-test/t/trigger-trans.test:
  Update error number, truncate is no longer invoked if
  table is parent in a FK relationship.
sql/ha_partition.cc:
  Reorganize the various truncate methods. delete_all_rows is now
  passed directly to the underlying engines, so as truncate. The
  code responsible for truncating individual partitions is moved
  to ha_partition::truncate_partition, which is invoked when a
  ALTER TABLE t1 TRUNCATE PARTITION p statement is executed.
  
  Since the partition truncate no longer can be invoked via
  delete, the bitmap operations are not necessary anymore. The
  explicit reset of the auto-increment value is also removed
  as the underlying engines are now responsible for reseting
  the value.
sql/handler.cc:
  Wire up the handler truncate method.
sql/handler.h:
  Introduce and document the truncate handler method. It assumes
  certain use cases of delete_all_rows.
  
  Add method to retrieve the list of foreign keys referencing a
  table. Method is used to avoid truncating tables that are
  parent in a foreign key relationship.
sql/share/errmsg-utf8.txt:
  Add error message for truncate and FK.
sql/sql_lex.h:
  Introduce a flag so that the partition engine can detect when
  a partition is being truncated. Used to give a special error.
sql/sql_parse.cc:
  Function mysql_truncate_table no longer exists.
sql/sql_partition_admin.cc:
  Implement the TRUNCATE PARTITION statement.
sql/sql_truncate.cc:
  Change the truncate table implementation to use the new truncate
  handler method and to not rely on row-by-row delete anymore.
  
  The truncate handler method is always invoked with a exclusive
  metadata lock. Also, it is no longer possible to truncate a
  table that is parent in some non-self-referencing foreign key.
storage/archive/ha_archive.cc:
  Rename method as the description indicates that in the future
  this could be a truncate operation.
storage/blackhole/ha_blackhole.cc:
  Implement truncate as no operation for the blackhole engine in
  order to remain compatible with older releases.
storage/federated/ha_federated.cc:
  Introduce truncate method that invokes delete_all_rows.
  This is required to support partition truncate as this
  form of truncate does not implement the drop and recreate
  protocol.
storage/heap/ha_heap.cc:
  Introduce truncate method that invokes delete_all_rows.
  This is required to support partition truncate as this
  form of truncate does not implement the drop and recreate
  protocol.
storage/ibmdb2i/ha_ibmdb2i.cc:
  Introduce truncate method that invokes delete_all_rows.
  This is required to support partition truncate as this
  form of truncate does not implement the drop and recreate
  protocol.
storage/innobase/handler/ha_innodb.cc:
  Rename delete_all_rows to truncate. InnoDB now does truncate
  under a exclusive metadata lock.
  
  Introduce and reorganize methods used to retrieve the list
  of foreign keys referenced by a or referencing a table.
storage/myisammrg/ha_myisammrg.cc:
  Introduce truncate method that invokes delete_all_rows.
  This is required in order to remain compatible with earlier
  releases where truncate would resort to a row-by-row delete.
2010-10-06 11:34:28 -03:00

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/* Copyright (C) 2000, 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 */
#ifdef USE_PRAGMA_INTERFACE
#pragma interface /* gcc class implementation */
#endif
/* class for the the myisam handler */
#include <myisam.h>
#include <ft_global.h>
#include "handler.h" /* handler */
#include "table.h" /* TABLE_SHARE */
struct TABLE_SHARE;
typedef struct st_ha_create_information HA_CREATE_INFO;
#define HA_RECOVER_DEFAULT 1 /* Automatic recover active */
#define HA_RECOVER_BACKUP 2 /* Make a backupfile on recover */
#define HA_RECOVER_FORCE 4 /* Recover even if we loose rows */
#define HA_RECOVER_QUICK 8 /* Don't check rows in data file */
#define HA_RECOVER_OFF 16 /* No automatic recover */
extern ulong myisam_sort_buffer_size;
extern TYPELIB myisam_recover_typelib;
extern const char *myisam_recover_names[];
extern ulonglong myisam_recover_options;
class ha_myisam: public handler
{
MI_INFO *file;
ulonglong int_table_flags;
char *data_file_name, *index_file_name;
bool can_enable_indexes;
int repair(THD *thd, MI_CHECK &param, bool optimize);
public:
ha_myisam(handlerton *hton, TABLE_SHARE *table_arg);
~ha_myisam() {}
handler *clone(MEM_ROOT *mem_root);
const char *table_type() const { return "MyISAM"; }
const char *index_type(uint key_number);
const char **bas_ext() const;
ulonglong table_flags() const { return int_table_flags; }
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; }
uint checksum() const;
int open(const char *name, int mode, uint test_if_locked);
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 ft_init()
{
if (!ft_handler)
return 1;
ft_handler->please->reinit_search(ft_handler);
return 0;
}
FT_INFO *ft_init_ext(uint flags, uint inx,String *key)
{
return ft_init_search(flags,file,inx,
(uchar *)key->ptr(), key->length(), key->charset(),
table->record[0]);
}
int ft_read(uchar *buf);
int rnd_init(bool scan);
int rnd_next(uchar *buf);
int rnd_pos(uchar * buf, uchar *pos);
int restart_rnd_next(uchar *buf, uchar *pos);
void position(const uchar *record);
int info(uint);
int extra(enum ha_extra_function operation);
int extra_opt(enum ha_extra_function operation, ulong cache_size);
int reset(void);
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);
void start_bulk_insert(ha_rows rows);
int end_bulk_insert();
ha_rows records_in_range(uint inx, key_range *min_key, key_range *max_key);
void update_create_info(HA_CREATE_INFO *create_info);
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);
virtual void get_auto_increment(ulonglong offset, ulonglong increment,
ulonglong nb_desired_values,
ulonglong *first_value,
ulonglong *nb_reserved_values);
int rename_table(const char * from, const char * to);
int delete_table(const char *name);
int check(THD* thd, HA_CHECK_OPT* check_opt);
int analyze(THD* thd,HA_CHECK_OPT* check_opt);
int repair(THD* thd, HA_CHECK_OPT* check_opt);
bool check_and_repair(THD *thd);
bool is_crashed() const;
bool auto_repair() const { return myisam_recover_options != HA_RECOVER_OFF; }
int optimize(THD* thd, HA_CHECK_OPT* check_opt);
int assign_to_keycache(THD* thd, HA_CHECK_OPT* check_opt);
int preload_keys(THD* thd, HA_CHECK_OPT* check_opt);
bool check_if_incompatible_data(HA_CREATE_INFO *info, uint table_changes);
#ifdef HAVE_QUERY_CACHE
my_bool register_query_cache_table(THD *thd, char *table_key,
uint key_length,
qc_engine_callback
*engine_callback,
ulonglong *engine_data);
#endif
MI_INFO *file_ptr(void)
{
return file;
}
};
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