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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.
151 lines
5.4 KiB
C++
151 lines
5.4 KiB
C++
/* Copyright (C) 2000-2006 MySQL AB
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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#ifdef USE_PRAGMA_INTERFACE
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#pragma interface /* gcc class implementation */
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#endif
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/* class for the the myisam merge handler */
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#include <myisammrg.h>
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/**
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Represents one name of a MERGE child.
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@todo: Add MYRG_SHARE and store chlidren names in the
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share.
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*/
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class Mrg_child_def: public Sql_alloc
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{
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/* Remembered MERGE child def version. See top comment in ha_myisammrg.cc */
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enum_table_ref_type m_child_table_ref_type;
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ulong m_child_def_version;
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public:
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LEX_STRING db;
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LEX_STRING name;
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/* Access MERGE child def version. See top comment in ha_myisammrg.cc */
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inline enum_table_ref_type get_child_table_ref_type()
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{
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return m_child_table_ref_type;
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}
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inline ulong get_child_def_version()
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{
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return m_child_def_version;
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}
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inline void set_child_def_version(enum_table_ref_type child_table_ref_type,
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ulong version)
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{
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m_child_table_ref_type= child_table_ref_type;
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m_child_def_version= version;
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}
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Mrg_child_def(char *db_arg, size_t db_len_arg,
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char *table_name_arg, size_t table_name_len_arg)
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{
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db.str= db_arg;
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db.length= db_len_arg;
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name.str= table_name_arg;
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name.length= table_name_len_arg;
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m_child_def_version= ~0UL;
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m_child_table_ref_type= TABLE_REF_NULL;
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}
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};
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class ha_myisammrg: public handler
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{
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MYRG_INFO *file;
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my_bool is_cloned; /* This instance has been cloned */
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public:
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MEM_ROOT children_mem_root; /* mem root for children list */
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List<Mrg_child_def> child_def_list;
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TABLE_LIST *children_l; /* children list */
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TABLE_LIST **children_last_l; /* children list end */
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uint test_if_locked; /* flags from ::open() */
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ha_myisammrg(handlerton *hton, TABLE_SHARE *table_arg);
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~ha_myisammrg();
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const char *table_type() const { return "MRG_MyISAM"; }
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const char **bas_ext() const;
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const char *index_type(uint key_number);
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ulonglong table_flags() const
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{
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return (HA_REC_NOT_IN_SEQ | HA_AUTO_PART_KEY | HA_NO_TRANSACTIONS |
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HA_BINLOG_ROW_CAPABLE | HA_BINLOG_STMT_CAPABLE |
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HA_NULL_IN_KEY | HA_CAN_INDEX_BLOBS | HA_FILE_BASED |
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HA_ANY_INDEX_MAY_BE_UNIQUE | HA_CAN_BIT_FIELD |
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HA_HAS_RECORDS |
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HA_NO_COPY_ON_ALTER |
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HA_DUPLICATE_POS);
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}
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ulong index_flags(uint inx, uint part, bool all_parts) const
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{
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return ((table_share->key_info[inx].algorithm == HA_KEY_ALG_FULLTEXT) ?
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0 : HA_READ_NEXT | HA_READ_PREV | HA_READ_RANGE |
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HA_READ_ORDER | HA_KEYREAD_ONLY);
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}
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uint max_supported_keys() const { return MI_MAX_KEY; }
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uint max_supported_key_length() const { return MI_MAX_KEY_LENGTH; }
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uint max_supported_key_part_length() const { return MI_MAX_KEY_LENGTH; }
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double scan_time()
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{ return ulonglong2double(stats.data_file_length) / IO_SIZE + file->tables; }
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int open(const char *name, int mode, uint test_if_locked);
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int add_children_list(void);
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int attach_children(void);
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int detach_children(void);
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virtual handler *clone(MEM_ROOT *mem_root);
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int close(void);
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int write_row(uchar * buf);
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int update_row(const uchar * old_data, uchar * new_data);
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int delete_row(const uchar * buf);
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int index_read_map(uchar *buf, const uchar *key, key_part_map keypart_map,
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enum ha_rkey_function find_flag);
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int index_read_idx_map(uchar *buf, uint index, const uchar *key,
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key_part_map keypart_map,
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enum ha_rkey_function find_flag);
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int index_read_last_map(uchar *buf, const uchar *key, key_part_map keypart_map);
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int index_next(uchar * buf);
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int index_prev(uchar * buf);
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int index_first(uchar * buf);
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int index_last(uchar * buf);
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int index_next_same(uchar *buf, const uchar *key, uint keylen);
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int rnd_init(bool scan);
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int rnd_next(uchar *buf);
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int rnd_pos(uchar * buf, uchar *pos);
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void position(const uchar *record);
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ha_rows records_in_range(uint inx, key_range *min_key, key_range *max_key);
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int truncate();
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int info(uint);
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int reset(void);
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int extra(enum ha_extra_function operation);
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int extra_opt(enum ha_extra_function operation, ulong cache_size);
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int external_lock(THD *thd, int lock_type);
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uint lock_count(void) const;
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int create(const char *name, TABLE *form, HA_CREATE_INFO *create_info);
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THR_LOCK_DATA **store_lock(THD *thd, THR_LOCK_DATA **to,
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enum thr_lock_type lock_type);
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void update_create_info(HA_CREATE_INFO *create_info);
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void append_create_info(String *packet);
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MYRG_INFO *myrg_info() { return file; }
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TABLE *table_ptr() { return table; }
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bool check_if_incompatible_data(HA_CREATE_INFO *info, uint table_changes);
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int check(THD* thd, HA_CHECK_OPT* check_opt);
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ha_rows records();
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};
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