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Fix for:

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Bug #20662 "Infinite loop in CREATE TABLE IF NOT EXISTS ... SELECT
              with locked tables"
  Bug #20903 "Crash when using CREATE TABLE .. SELECT and triggers"
  Bug #24738 "CREATE TABLE ... SELECT is not isolated properly"
  Bug #24508 "Inconsistent results of CREATE TABLE ... SELECT when
              temporary table exists"
 
Deadlock occured when one tried to execute CREATE TABLE IF NOT
EXISTS ... SELECT statement under LOCK TABLES which held
read lock on target table.
Attempt to execute the same statement for already existing
target table with triggers caused server crashes.
Also concurrent execution of CREATE TABLE ... SELECT statement
and other statements involving target table suffered from
various races (some of which might've led to deadlocks).
Finally, attempt to execute CREATE TABLE ... SELECT in case
when a temporary table with same name was already present
led to the insertion of data into this temporary table and
creation of empty non-temporary table.
 
All above problems stemmed from the old implementation of CREATE
TABLE ... SELECT in which we created, opened and locked target
table without any special protection in a separate step and not
with the rest of tables used by this statement.
This underminded deadlock-avoidance approach used in server
and created window for races. It also excluded target table
from prelocking causing problems with trigger execution.
  
The patch solves these problems by implementing new approach to
handling of CREATE TABLE ... SELECT for base tables.
We try to open and lock table to be created at the same time as
the rest of tables used by this statement. If such table does not
exist at this moment we create and place in the table cache special
placeholder for it which prevents its creation or any other usage
by other threads.

We still use old approach for creation of temporary tables.

Also note that we decided to postpone introduction of some tests
for concurrent behaviour of CREATE TABLE ... SELECT till 5.1.
The main reason for this is absence in 5.0 ability to set @@debug
variable at runtime, which can be circumvented only by using several
test files with individual .opt files. Since the latter is likely
to slowdown test-suite unnecessary we chose not to push this tests
into 5.0, but run them manually for this version and later push
their optimized version into 5.1
This commit is contained in:
dlenev@mockturtle.local
2007-05-11 20:33:13 +04:00
parent 4b0d37362b
commit 8b93e52e92
15 changed files with 918 additions and 183 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
sql/mysql_priv.h
View File

@ -674,6 +674,8 @@ struct Query_cache_query_flags
#define query_cache_invalidate_by_MyISAM_filename_ref NULL
#endif /*HAVE_QUERY_CACHE*/
uint build_table_path(char *buff, size_t bufflen, const char *db,
const char *table, const char *ext);
bool mysql_create_db(THD *thd, char *db, HA_CREATE_INFO *create, bool silent);
bool mysql_alter_db(THD *thd, const char *db, HA_CREATE_INFO *create);
bool mysql_rm_db(THD *thd,char *db,bool if_exists, bool silent);
@ -856,12 +858,14 @@ bool mysql_create_or_drop_trigger(THD *thd, TABLE_LIST *tables, bool create);
TABLE *open_ltable(THD *thd, TABLE_LIST *table_list, thr_lock_type update);
TABLE *open_table(THD *thd, TABLE_LIST *table_list, MEM_ROOT* mem,
bool *refresh, uint flags);
bool reopen_name_locked_table(THD* thd, TABLE_LIST* table);
bool reopen_name_locked_table(THD* thd, TABLE_LIST* table_list, bool link_in);
TABLE *table_cache_insert_placeholder(THD *thd, const char *key,
uint key_length);
bool table_cache_has_open_placeholder(THD *thd, const char *db,
const char *table_name);
TABLE *find_locked_table(THD *thd, const char *db,const char *table_name);
bool reopen_table(TABLE *table,bool locked);
bool reopen_tables(THD *thd,bool get_locks,bool in_refresh);
void close_old_data_files(THD *thd, TABLE *table, bool abort_locks,
bool send_refresh);
bool close_data_tables(THD *thd,const char *db, const char *table_name);
bool wait_for_tables(THD *thd);
bool table_is_used(TABLE *table, bool wait_for_name_lock);
@ -1017,6 +1021,8 @@ void add_join_natural(TABLE_LIST *a,TABLE_LIST *b,List<String> *using_fields,
SELECT_LEX *lex);
bool add_proc_to_list(THD *thd, Item *item);
TABLE *unlink_open_table(THD *thd,TABLE *list,TABLE *find);
void drop_open_table(THD *thd, TABLE *table, const char *db_name,
const char *table_name);
void update_non_unique_table_error(TABLE_LIST *update,
const char *operation,
TABLE_LIST *duplicate);
@ -1269,7 +1275,7 @@ extern double log_01[32];
extern ulonglong log_10_int[20];
extern ulonglong keybuff_size;
extern ulonglong thd_startup_options;
extern ulong refresh_version,flush_version, thread_id;
extern ulong flush_version, thread_id;
extern ulong binlog_cache_use, binlog_cache_disk_use;
extern ulong aborted_threads,aborted_connects;
extern ulong delayed_insert_timeout;
@ -1443,7 +1449,7 @@ MYSQL_LOCK *mysql_lock_tables(THD *thd, TABLE **table, uint count,
#define MYSQL_LOCK_IGNORE_GLOBAL_READ_LOCK 0x0001
#define MYSQL_LOCK_IGNORE_FLUSH 0x0002
#define MYSQL_LOCK_NOTIFY_IF_NEED_REOPEN 0x0004
#define MYSQL_OPEN_IGNORE_LOCKED_TABLES 0x0008
#define MYSQL_OPEN_TEMPORARY_ONLY 0x0008
void mysql_unlock_tables(THD *thd, MYSQL_LOCK *sql_lock);
void mysql_unlock_read_tables(THD *thd, MYSQL_LOCK *sql_lock);