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A 5.5 version of the fix for Bug #54360 "Deadlock DROP/ALTER/CREATE

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DATABASE with open HANDLER"

Remove LOCK_create_db, database name locks, and use metadata locks instead.
This exposes CREATE/DROP/ALTER DATABASE statements to the graph-based
deadlock detector in MDL, and paves the way for a safe, deadlock-free
implementation of RENAME DATABASE.

Database DDL statements will now take exclusive metadata locks on
the database name, while table/view/routine DDL statements take
intention exclusive locks on the database name. This prevents race
conditions between database DDL and table/view/routine DDL.
(e.g. DROP DATABASE with concurrent CREATE/ALTER/DROP TABLE)

By adding database name locks, this patch implements
WL#4450 "DDL locking: CREATE/DROP DATABASE must use database locks" and
WL#4985 "DDL locking: namespace/hierarchical locks".

The patch also changes code to use init_one_table() where appropriate.
The new lock_table_names() function requires TABLE_LIST::db_length to
be set correctly, and this is taken care of by init_one_table().

This patch also adds a simple template to help work with 
the mysys HASH data structure.

Most of the patch was written by Konstantin Osipov.
This commit is contained in:
Jon Olav Hauglid
2010-07-01 15:53:46 +02:00
parent 34e409fafa
commit 41a3dfe490
28 changed files with 1300 additions and 652 deletions
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7
sql/sql_db.h
View File

@@ -35,8 +35,8 @@ bool mysql_opt_change_db(THD *thd,
LEX_STRING *saved_db_name,
bool force_switch,
bool *cur_db_changed);
bool my_database_names_init(void);
void my_database_names_free(void);
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, HA_CREATE_INFO *create);
bool load_db_opt_by_name(THD *thd, const char *db_name,
@@ -45,9 +45,6 @@ CHARSET_INFO *get_default_db_collation(THD *thd, const char *db_name);
bool my_dbopt_init(void);
void my_dbopt_cleanup(void);
extern int creating_database; // How many database locks are made
extern HASH lock_db_cache;
#define MY_DB_OPT_FILE "db.opt"
#endif /* SQL_DB_INCLUDED */