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5bcb1d6532
The used code is largely based on code from Tencent
The problem is that in some rare cases there may be a conflict between .frm
files and the files in the storage engine. In this case the DROP TABLE
was not able to properly drop the table.
Some MariaDB/MySQL forks has solved this by adding a FORCE option to
DROP TABLE. After some discussion among MariaDB developers, we concluded
that users expects that DROP TABLE should always work, even if the
table would not be consistent. There should not be a need to use a
separate keyword to ensure that the table is really deleted.
The used solution is:
- If a .frm table doesn't exists, try dropping the table from all storage
engines.
- If the .frm table exists but the table does not exist in the engine
try dropping the table from all storage engines.
- Update storage engines using many table files (.CVS, MyISAM, Aria) to
succeed with the drop even if some of the files are missing.
- Add HTON_AUTOMATIC_DELETE_TABLE to handlerton's where delete_table()
is not needed and always succeed. This is used by ha_delete_table_force()
to know which handlers to ignore when trying to drop a table without
a .frm file.
The disadvantage of this solution is that a DROP TABLE on a non existing
table will be a bit slower as we have to ask all active storage engines
if they know anything about the table.
Other things:
- Added a new flag MY_IGNORE_ENOENT to my_delete() to not give an error
if the file doesn't exist. This simplifies some of the code.
- Don't clear thd->error in ha_delete_table() if there was an active
error. This is a bug fix.
- handler::delete_table() will not abort if first file doesn't exists.
This is bug fix to handle the case when a drop table was aborted in
the middle.
- Cleaned up mysql_rm_table_no_locks() to ensure that if_exists uses
same code path as when it's not used.
- Use non_existing_Table_error() to detect if table didn't exists.
Old code used different errors tests in different position.
- Table_triggers_list::drop_all_triggers() now drops trigger file if
it can't be parsed instead of leaving it hanging around (bug fix)
- InnoDB doesn't anymore print error about .frm file out of sync with
InnoDB directory if .frm file does not exists. This change was required
to be able to try to drop an InnoDB file when .frm doesn't exists.
- Fixed bug in mi_delete_table() where the .MYD file would not be dropped
if the .MYI file didn't exists.
- Fixed memory leak in Mroonga when deleting non existing table
- Fixed memory leak in Connect when deleting non existing table
Bugs fixed introduced by the original version of this commit:
MDEV-22826 Presence of Spider prevents tables from being force-deleted from
other engines
106 lines
3.9 KiB
C++
106 lines
3.9 KiB
C++
/* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
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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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335 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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#include "thr_lock.h" /* THR_LOCK */
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#include "handler.h" /* handler */
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#include "table.h" /* TABLE_SHARE */
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/*
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Shared structure for correct LOCK operation
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*/
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struct st_blackhole_share {
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THR_LOCK lock;
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uint use_count;
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uint table_name_length;
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char table_name[1];
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};
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/*
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Class definition for the blackhole storage engine
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"Dumbest named feature ever"
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*/
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class ha_blackhole: public handler
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{
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THR_LOCK_DATA lock; /* MySQL lock */
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st_blackhole_share *share;
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public:
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ha_blackhole(handlerton *hton, TABLE_SHARE *table_arg);
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~ha_blackhole()
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{
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}
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/*
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The name of the index type that will be used for display
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don't implement this method unless you really have indexes
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*/
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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_NULL_IN_KEY | HA_CAN_FULLTEXT | HA_CAN_SQL_HANDLER |
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HA_BINLOG_STMT_CAPABLE | HA_BINLOG_ROW_CAPABLE |
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HA_CAN_INDEX_BLOBS | HA_AUTO_PART_KEY | HA_CAN_ONLINE_BACKUPS |
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HA_FILE_BASED | HA_CAN_GEOMETRY | HA_CAN_INSERT_DELAYED);
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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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/* The following defines can be increased if necessary */
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#define BLACKHOLE_MAX_KEY 64 /* Max allowed keys */
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#define BLACKHOLE_MAX_KEY_SEG 16 /* Max segments for key */
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#define BLACKHOLE_MAX_KEY_LENGTH 1000
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uint max_supported_keys() const { return BLACKHOLE_MAX_KEY; }
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uint max_supported_key_length() const { return BLACKHOLE_MAX_KEY_LENGTH; }
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uint max_supported_key_part_length() const { return BLACKHOLE_MAX_KEY_LENGTH; }
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int open(const char *name, int mode, uint test_if_locked);
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int close(void);
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int truncate();
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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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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 idx, 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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void position(const uchar *record);
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int info(uint flag);
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int external_lock(THD *thd, int lock_type);
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int create(const char *name, TABLE *table_arg,
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HA_CREATE_INFO *create_info);
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THR_LOCK_DATA **store_lock(THD *thd,
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THR_LOCK_DATA **to,
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enum thr_lock_type lock_type);
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int delete_table(const char *name)
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{
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return 0;
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}
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private:
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virtual int write_row(const uchar *buf);
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virtual int update_row(const uchar *old_data, const uchar *new_data);
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virtual int delete_row(const uchar *buf);
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};
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