mariadb/sql/sql_db.h
Monty 7a588c30b1 MDEV-24408 Crash-safe DROP DATABASE
Description of how DROP DATABASE works after this patch

- Collect list of tables
- DDL log tables as they are dropped
- DDL log drop database
- Delete db.opt
- Delete data directory
- Log either DROP TABLE or DROP DATABASE to binary log
- De active ddl log entry

This is in line of how things where before (minus ddl logging) except that
we delete db.opt file last to not loose it if DROP DATABASE fails.

On recovery we have to ensure that all dropped tables are logged in
binary log and that they are properly dropped (as with atomic drop
table).
No new tables be dropped as part of recovery.

Recovery of active drop database ddl log entry:

- If drop database was logged to ddl log but was not found in the binary
  log:
  - drop the db.opt file and database directory.
  - Log DROP DATABASE to binary log
- If drop database was not logged to ddl log
  - Update binary log with DROP TABLE of the dropped tables. If table list
    is longer than max_allowed_packet, then the query will be split into
    multiple DROP TABLE/VIEW queries.

Other things:
- Added DDL_LOG_STATE and 'current database' as arguments to
  mysql_rm_table_no_locks(). This was needed to be able to combine
  ddl logging of DROP DATABASE and DROP TABLE and make the generated
  DROP TABLE statements shorter.
- To make the DROP TABLE statement created by ddl log shorter, I changed
  the binlogged query to use current directory and omit the directory
  part for all tables in the current directory.
- Merged some DROP TABLE and DROP VIEW code in ddl logger.  This was done
  to be able get separate DROP VIEW and DROP TABLE statements in the binary
  log.
- Added a 'recovery_state' variable to remember the state of dropped
  tables and views.
- Moved out code that drops database objects (stored procedures) from
  mysql_rm_db_internal() to drop_database_objects() for better code reuse.
- Made mysql_rm_db_internal() global so that could be used by the ddl
  recovery code.
2021-05-19 22:54:13 +02:00

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/* Copyright (c) 2006, 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 02110-1335 USA */
#ifndef SQL_DB_INCLUDED
#define SQL_DB_INCLUDED
#include "hash.h" /* HASH */
class THD;
int mysql_create_db(THD *thd, const LEX_CSTRING *db, DDL_options_st options,
const Schema_specification_st *create);
bool mysql_alter_db(THD *thd, const LEX_CSTRING *db,
const Schema_specification_st *create);
bool mysql_rm_db(THD *thd, const LEX_CSTRING *db, bool if_exists);
bool mysql_upgrade_db(THD *thd, const LEX_CSTRING *old_db);
uint mysql_change_db(THD *thd, const LEX_CSTRING *new_db_name,
bool force_switch);
bool mysql_opt_change_db(THD *thd,
const LEX_CSTRING *new_db_name,
LEX_STRING *saved_db_name,
bool force_switch,
bool *cur_db_changed);
bool my_dboptions_cache_init(void);
void my_dboptions_cache_free(void);
bool check_db_dir_existence(const char *db_name);
bool load_db_opt(THD *thd, const char *path, Schema_specification_st *create);
bool load_db_opt_by_name(THD *thd, const char *db_name,
Schema_specification_st *db_create_info);
CHARSET_INFO *get_default_db_collation(THD *thd, const char *db_name);
bool my_dbopt_init(void);
void my_dbopt_cleanup(void);
const char *normalize_db_name(const char *db, char *buffer,
size_t buffer_size);
void drop_database_objects(THD *thd, const LEX_CSTRING *path,
const LEX_CSTRING *db,
bool rm_mysql_schema);
my_bool rm_dir_w_symlink(const char *org_path, my_bool send_error);
#define MY_DB_OPT_FILE "db.opt"
#endif /* SQL_DB_INCLUDED */