diff options
Diffstat (limited to 'sql')
| -rw-r--r-- | sql/lock.cc | 33 | ||||
| -rw-r--r-- | sql/mysql_priv.h | 16 | ||||
| -rw-r--r-- | sql/sql_base.cc | 420 | ||||
| -rw-r--r-- | sql/sql_handler.cc | 25 | ||||
| -rw-r--r-- | sql/sql_insert.cc | 182 | ||||
| -rw-r--r-- | sql/sql_parse.cc | 12 | ||||
| -rw-r--r-- | sql/sql_prepare.cc | 15 | ||||
| -rw-r--r-- | sql/sql_table.cc | 88 | ||||
| -rw-r--r-- | sql/sql_trigger.cc | 2 | ||||
| -rw-r--r-- | sql/sql_yacc.yy | 4 | ||||
| -rw-r--r-- | sql/table.h | 40 |
11 files changed, 653 insertions, 184 deletions
diff --git a/sql/lock.cc b/sql/lock.cc index 233d12d9cc4..9298b33b4d2 100644 --- a/sql/lock.cc +++ b/sql/lock.cc @@ -853,7 +853,6 @@ int lock_table_name(THD *thd, TABLE_LIST *table_list) TABLE *table; char key[MAX_DBKEY_LENGTH]; char *db= table_list->db; - int table_in_key_offset; uint key_length; HASH_SEARCH_STATE state; DBUG_ENTER("lock_table_name"); @@ -861,10 +860,8 @@ int lock_table_name(THD *thd, TABLE_LIST *table_list) safe_mutex_assert_owner(&LOCK_open); - table_in_key_offset= strmov(key, db) - key + 1; - key_length= (uint)(strmov(key + table_in_key_offset, table_list->table_name) - - key) + 1; - + key_length= (uint)(strmov(strmov(key, db) + 1, table_list->table_name) - + key) + 1; /* Only insert the table if we haven't insert it already */ for (table=(TABLE*) hash_first(&open_cache, (byte*)key, key_length, &state); @@ -873,29 +870,11 @@ int lock_table_name(THD *thd, TABLE_LIST *table_list) if (table->in_use == thd) DBUG_RETURN(0); - /* - Create a table entry with the right key and with an old refresh version - Note that we must use my_malloc() here as this is freed by the table - cache - */ - if (!(table= (TABLE*) my_malloc(sizeof(*table)+key_length, - MYF(MY_WME | MY_ZEROFILL)))) - DBUG_RETURN(-1); - table->s= &table->share_not_to_be_used; - memcpy((table->s->table_cache_key= (char*) (table+1)), key, key_length); - table->s->db= table->s->table_cache_key; - table->s->table_name= table->s->table_cache_key + table_in_key_offset; - table->s->key_length=key_length; - table->in_use=thd; - table->locked_by_name=1; - table_list->table=table; - - if (my_hash_insert(&open_cache, (byte*) table)) - { - my_free((gptr) table,MYF(0)); + if (!(table= table_cache_insert_placeholder(thd, key, key_length))) DBUG_RETURN(-1); - } - + + table_list->table= table; + /* Return 1 if table is in use */ DBUG_RETURN(test(remove_table_from_cache(thd, db, table_list->table_name, RTFC_NO_FLAG))); diff --git a/sql/mysql_priv.h b/sql/mysql_priv.h index 868f3584448..37a5fc31f1d 100644 --- a/sql/mysql_priv.h +++ b/sql/mysql_priv.h @@ -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); diff --git a/sql/sql_base.cc b/sql/sql_base.cc index 6e6611d54d2..db4491a19ae 100644 --- a/sql/sql_base.cc +++ b/sql/sql_base.cc @@ -94,6 +94,8 @@ static bool open_new_frm(THD *thd, const char *path, const char *alias, uint db_stat, uint prgflag, uint ha_open_flags, TABLE *outparam, TABLE_LIST *table_desc, MEM_ROOT *mem_root); +static void close_old_data_files(THD *thd, TABLE *table, bool morph_locks, + bool send_refresh); extern "C" byte *table_cache_key(const byte *record,uint *length, my_bool not_used __attribute__((unused))) @@ -374,7 +376,21 @@ bool close_cached_tables(THD *thd, bool if_wait_for_refresh, for (uint idx=0 ; idx < open_cache.records ; idx++) { TABLE *table=(TABLE*) hash_element(&open_cache,idx); - if ((table->s->version) < refresh_version && table->db_stat) + /* + Note that we wait here only for tables which are actually open, and + not for placeholders with TABLE::open_placeholder set. Waiting for + latter will cause deadlock in the following scenario, for example: + + conn1: lock table t1 write; + conn2: lock table t2 write; + conn1: flush tables; + conn2: flush tables; + + It also does not make sense to wait for those of placeholders that + are employed by CREATE TABLE as in this case table simply does not + exist yet. + */ + if (table->needs_reopen_or_name_lock() && table->db_stat) { found=1; DBUG_PRINT("signal", ("Waiting for COND_refresh")); @@ -616,10 +632,10 @@ bool close_thread_table(THD *thd, TABLE **table_ptr) TABLE *table= *table_ptr; DBUG_ENTER("close_thread_table"); DBUG_ASSERT(table->key_read == 0); - DBUG_ASSERT(table->file->inited == handler::NONE); + DBUG_ASSERT(!table->file || table->file->inited == handler::NONE); *table_ptr=table->next; - if (table->s->version != refresh_version || + if (table->needs_reopen_or_name_lock() || thd->version != refresh_version || !table->db_stat) { VOID(hash_delete(&open_cache,(byte*) table)); @@ -627,6 +643,12 @@ bool close_thread_table(THD *thd, TABLE **table_ptr) } else { + /* + Open placeholders have TABLE::db_stat set to 0, so they should be + handled by the first alternative. + */ + DBUG_ASSERT(!table->open_placeholder); + if (table->s->flush_version != flush_version) { table->s->flush_version= flush_version; @@ -1114,6 +1136,43 @@ TABLE *unlink_open_table(THD *thd, TABLE *list, TABLE *find) } +/** + @brief Auxiliary routine which closes and drops open table. + + @param thd Thread handle + @param table TABLE object for table to be dropped + @param db_name Name of database for this table + @param table_name Name of this table + + @note This routine assumes that table to be closed is open only + by calling thread so we needn't wait until other threads + will close the table. Also unless called under implicit or + explicit LOCK TABLES mode it assumes that table to be + dropped is already unlocked. In the former case it will + also remove lock on the table. But one should not rely on + this behaviour as it may change in future. +*/ + +void drop_open_table(THD *thd, TABLE *table, const char *db_name, + const char *table_name) +{ + if (table->s->tmp_table) + close_temporary_table(thd, db_name, table_name); + else + { + enum db_type table_type= table->s->db_type; + VOID(pthread_mutex_lock(&LOCK_open)); + /* + unlink_open_table() also tells threads waiting for refresh or close + that something has happened. + */ + thd->open_tables= unlink_open_table(thd, thd->open_tables, table); + quick_rm_table(table_type, db_name, table_name); + VOID(pthread_mutex_unlock(&LOCK_open)); + } +} + + /* When we call the following function we must have a lock on LOCK_open ; This lock will be unlocked on return. @@ -1152,6 +1211,11 @@ void wait_for_refresh(THD *thd) table_list TABLE_LIST object for table to be open, TABLE_LIST::table member should point to TABLE object which was used for name-locking. + link_in TRUE - if TABLE object for table to be opened should be + linked into THD::open_tables list. + FALSE - placeholder used for name-locking is already in + this list so we only need to preserve TABLE::next + pointer. NOTE This function assumes that its caller already acquired LOCK_open mutex. @@ -1161,7 +1225,7 @@ void wait_for_refresh(THD *thd) TRUE - Error */ -bool reopen_name_locked_table(THD* thd, TABLE_LIST* table_list) +bool reopen_name_locked_table(THD* thd, TABLE_LIST* table_list, bool link_in) { TABLE *table= table_list->table; TABLE_SHARE *share; @@ -1199,12 +1263,33 @@ bool reopen_name_locked_table(THD* thd, TABLE_LIST* table_list) share= table->s; share->db= share->table_cache_key; share->key_length=key_length; + /* + We want to prevent other connections from opening this table until end + of statement as it is likely that modifications of table's metadata are + not yet finished (for example CREATE TRIGGER have to change .TRG file, + or we might want to drop table if CREATE TABLE ... SELECT fails). + This also allows us to assume that no other connection will sneak in + before we will get table-level lock on this table. + */ share->version=0; share->flush_version=0; table->in_use = thd; check_unused(); - table->next = thd->open_tables; - thd->open_tables = table; + + if (link_in) + { + table->next= thd->open_tables; + thd->open_tables= table; + } + else + { + /* + TABLE object should be already in THD::open_tables list so we just + need to set TABLE::next correctly. + */ + table->next= orig_table.next; + } + table->tablenr=thd->current_tablenr++; table->used_fields=0; table->const_table=0; @@ -1216,6 +1301,167 @@ bool reopen_name_locked_table(THD* thd, TABLE_LIST* table_list) } +/** + @brief Create and insert into table cache placeholder for table + which will prevent its opening (or creation) (a.k.a lock + table name). + + @param thd Thread context + @param key Table cache key for name to be locked + @param key_length Table cache key length + + @return Pointer to TABLE object used for name locking or 0 in + case of failure. +*/ + +TABLE *table_cache_insert_placeholder(THD *thd, const char *key, + uint key_length) +{ + TABLE *table; + char *key_buff; + DBUG_ENTER("table_cache_insert_placeholder"); + + safe_mutex_assert_owner(&LOCK_open); + + /* + Create a table entry with the right key and with an old refresh version + Note that we must use my_multi_malloc() here as this is freed by the + table cache + */ + if (!my_multi_malloc(MYF(MY_WME | MY_ZEROFILL), + &table, sizeof(*table), + &key_buff, key_length, + NULL)) + DBUG_RETURN(NULL); + + table->s= &table->share_not_to_be_used; + memcpy(key_buff, key, key_length); + table->s->table_cache_key= key_buff; + table->s->db= table->s->table_cache_key; + table->s->table_name= table->s->table_cache_key + strlen(table->s->db) + 1; + table->s->key_length= key_length; + table->in_use= thd; + table->locked_by_name= 1; + + if (my_hash_insert(&open_cache, (byte*)table)) + { + my_free((gptr) table, MYF(0)); + DBUG_RETURN(NULL); + } + + DBUG_RETURN(table); +} + + +/** + @brief Check if table cache contains an open placeholder for the + table and if this placeholder was created by another thread. + + @param thd Thread context + @param db Name of database for table in question + @param table_name Table name + + @note The presence of open placeholder indicates that either some + other thread is trying to create table in question and obtained + an exclusive name-lock on it or that this table already exists + and is being flushed at the moment. + + @note One should acquire LOCK_open mutex before calling this function. + + @note This function is a hack which was introduced in 5.0 only to + minimize code changes. It doesn't present in 5.1. + + @retval TRUE Table cache contains open placeholder for the table + which was created by some other thread. + @retval FALSE Otherwise. +*/ + +bool table_cache_has_open_placeholder(THD *thd, const char *db, + const char *table_name) +{ + char key[MAX_DBKEY_LENGTH]; + uint key_length; + HASH_SEARCH_STATE state; + TABLE *search; + DBUG_ENTER("table_cache_has_open_placeholder"); + + safe_mutex_assert_owner(&LOCK_open); + + key_length=(uint) (strmov(strmov(key,db)+1,table_name)-key)+1; + for (search= (TABLE*) hash_first(&open_cache, (byte*) key, key_length, + &state); + search ; + search= (TABLE*) hash_next(&open_cache, (byte*) key, key_length, + &state)) + { + if (search->in_use == thd) + continue; + if (search->open_placeholder) + DBUG_RETURN(1); + } + DBUG_RETURN(0); +} + + +/** + @brief Check that table exists on disk or in some storage engine. + + @param thd Thread context + @param table Table list element + @param exists[out] Out parameter which is set to TRUE if table + exists and to FALSE otherwise. + + @note This function assumes that caller owns LOCK_open mutex. + It also assumes that the fact that there are no name-locks + on the table was checked beforehand. + + @note If there is no .FRM file for the table but it exists in one + of engines (e.g. it was created on another node of NDB cluster) + this function will fetch and create proper .FRM file for it. + + @retval TRUE Some error occured + @retval FALSE No error. 'exists' out parameter set accordingly. +*/ + +bool check_if_table_exists(THD *thd, TABLE_LIST *table, bool *exists) +{ + char path[FN_REFLEN]; + int rc; + DBUG_ENTER("check_if_table_exists"); + + safe_mutex_assert_owner(&LOCK_open); + + *exists= TRUE; + + build_table_path(path, sizeof(path), table->db, table->table_name, reg_ext); + + if (!access(path, F_OK)) + DBUG_RETURN(FALSE); + + /* .FRM file doesn't exist. Check if some engine can provide it. */ + + rc= ha_create_table_from_engine(thd, table->db, table->table_name); + + if (rc < 0) + { + /* Table does not exists in engines as well. */ + *exists= FALSE; + DBUG_RETURN(FALSE); + } + else if (!rc) + { + /* Table exists in some engine and .FRM for it was created. */ + DBUG_RETURN(FALSE); + } + else /* (rc > 0) */ + { + my_printf_error(ER_UNKNOWN_ERROR, "Failed to open '%-.64s', error while " + "unpacking from engine", MYF(0), table->table_name); + DBUG_RETURN(TRUE); + } +} + + /* Open a table. @@ -1231,12 +1477,17 @@ bool reopen_name_locked_table(THD* thd, TABLE_LIST* table_list) MYSQL_LOCK_IGNORE_FLUSH - Open table even if someone has done a flush or namelock on it. No version number checking is done. - MYSQL_OPEN_IGNORE_LOCKED_TABLES - Open table - ignoring set of locked tables and prelocked mode. + MYSQL_OPEN_TEMPORARY_ONLY - Open only temporary + table not the base table or view. IMPLEMENTATION Uses a cache of open tables to find a table not in use. + If table list element for the table to be opened has "create" flag + set and table does not exist, this function will automatically insert + a placeholder for exclusive name lock into the open tables cache and + will return the TABLE instance that corresponds to this placeholder. + RETURN NULL Open failed. If refresh is set then one should close all other tables and retry the open. @@ -1305,6 +1556,12 @@ TABLE *open_table(THD *thd, TABLE_LIST *table_list, MEM_ROOT *mem_root, } } + if (flags & MYSQL_OPEN_TEMPORARY_ONLY) + { + my_error(ER_NO_SUCH_TABLE, MYF(0), table_list->db, table_list->table_name); + DBUG_RETURN(0); + } + /* The table is not temporary - if we're in pre-locked or LOCK TABLES mode, let's try to find the requested table in the list of pre-opened @@ -1312,8 +1569,7 @@ TABLE *open_table(THD *thd, TABLE_LIST *table_list, MEM_ROOT *mem_root, open not pre-opened tables in pre-locked/LOCK TABLES mode. TODO: move this block into a separate function. */ - if (!(flags & MYSQL_OPEN_IGNORE_LOCKED_TABLES) && - (thd->locked_tables || thd->prelocked_mode)) + if (thd->locked_tables || thd->prelocked_mode) { // Using table locks TABLE *best_table= 0; int best_distance= INT_MIN; @@ -1495,7 +1751,7 @@ TABLE *open_table(THD *thd, TABLE_LIST *table_list, MEM_ROOT *mem_root, c1: name lock t2; -- blocks c2: open t1; -- blocks */ - if (table->s->version != refresh_version) + if (table->needs_reopen_or_name_lock()) { DBUG_PRINT("note", ("Found table '%s.%s' with different refresh version", @@ -1507,6 +1763,14 @@ TABLE *open_table(THD *thd, TABLE_LIST *table_list, MEM_ROOT *mem_root, continue; } + /* Avoid self-deadlocks by detecting self-dependencies. */ + if (table->open_placeholder && table->in_use == thd) + { + VOID(pthread_mutex_unlock(&LOCK_open)); + my_error(ER_UPDATE_TABLE_USED, MYF(0), table->s->table_name); + DBUG_RETURN(0); + } + /* Back off, part 1: mark the table as "unused" for the purpose of name-locking by setting table->db_stat to 0. Do @@ -1523,6 +1787,14 @@ TABLE *open_table(THD *thd, TABLE_LIST *table_list, MEM_ROOT *mem_root, and wait till the operation is complete: when any operation that juggles with table->s->version completes, it broadcasts COND_refresh condition variable. + If 'old' table we met is in use by current thread we return + without waiting since in this situation it's this thread + which is responsible for broadcasting on COND_refresh + (and this was done already in close_old_data_files()). + Good example of such situation is when we have statement + that needs two instances of table and FLUSH TABLES comes + after we open first instance but before we open second + instance. */ if (table->in_use != thd) { @@ -1564,6 +1836,40 @@ TABLE *open_table(THD *thd, TABLE_LIST *table_list, MEM_ROOT *mem_root, while (open_cache.records > table_cache_size && unused_tables) VOID(hash_delete(&open_cache,(byte*) unused_tables)); /* purecov: tested */ + if (table_list->create) + { + bool exists; + + if (check_if_table_exists(thd, table_list, &exists)) + { + VOID(pthread_mutex_unlock(&LOCK_open)); + DBUG_RETURN(NULL); + } + + if (!exists) + { + /* + Table to be created, so we need to create placeholder in table-cache. + */ + if (!(table= table_cache_insert_placeholder(thd, key, key_length))) + { + VOID(pthread_mutex_unlock(&LOCK_open)); + DBUG_RETURN(NULL); + } + /* + Link placeholder to the open tables list so it will be automatically + removed once tables are closed. Also mark it so it won't be ignored + by other trying to take name-lock. + */ + table->open_placeholder= 1; + table->next= thd->open_tables; + thd->open_tables= table; + VOID(pthread_mutex_unlock(&LOCK_open)); + DBUG_RETURN(table); + } + /* Table exists. Let us try to open it. */ + } + /* make a new table */ if (!(table=(TABLE*) my_malloc(sizeof(*table),MYF(MY_WME)))) { @@ -1794,9 +2100,24 @@ bool close_data_tables(THD *thd,const char *db, const char *table_name) } -/* - Reopen all tables with closed data files - One should have lock on LOCK_open when calling this +/** + @brief Reopen all tables with closed data files. + + @param thd Thread context + @param get_locks Should we get locks after reopening tables ? + @param in_refresh Are we in FLUSH TABLES ? TODO: It seems that + we can remove this parameter. + + @note Since this function can't properly handle prelocking and + create placeholders it should be used in very special + situations like FLUSH TABLES or ALTER TABLE. In general + case one should just repeat open_tables()/lock_tables() + combination when one needs tables to be reopened (for + example see open_and_lock_tables()). + + @note One should have lock on LOCK_open when calling this. + + @return FALSE in case of success, TRUE - otherwise. */ bool reopen_tables(THD *thd,bool get_locks,bool in_refresh) @@ -1841,7 +2162,7 @@ bool reopen_tables(THD *thd,bool get_locks,bool in_refresh) if (in_refresh) { table->s->version=0; - table->locked_by_flush=0; + table->open_placeholder= 0; } } } @@ -1867,35 +2188,71 @@ bool reopen_tables(THD *thd,bool get_locks,bool in_refresh) DBUG_RETURN(error); } -/* - Close handlers for tables in list, but leave the TABLE structure - intact so that we can re-open these quickly - abort_locks is set if called from flush_tables. + +/** + @brief Close handlers for tables in list, but leave the TABLE structure + intact so that we can re-open these quickly. + + @param thd Thread context + @param table Head of the list of TABLE objects + @param morph_locks TRUE - remove locks which we have on tables being closed + but ensure that no DML or DDL will sneak in before + we will re-open the table (i.e. temporarily morph + our table-level locks into name-locks). + FALSE - otherwise + @param send_refresh Should we awake waiters even if we didn't close any tables? */ -void close_old_data_files(THD *thd, TABLE *table, bool abort_locks, +void close_old_data_files(THD *thd, TABLE *table, bool morph_locks, bool send_refresh) { DBUG_ENTER("close_old_data_files"); bool found=send_refresh; for (; table ; table=table->next) { - if (table->s->version != refresh_version) + if (table->needs_reopen_or_name_lock()) { found=1; - if (!abort_locks) // If not from flush tables + /* + Note that it is safe to update version even for open placeholders + as later in this function we reset TABLE::open_placeholder and thus + effectively remove them from the table cache. + */ + if (!morph_locks) // If not from flush tables table->s->version= refresh_version; // Let other threads use table if (table->db_stat) { - if (abort_locks) - { - mysql_lock_abort(thd,table); // Close waiting threads - mysql_lock_remove(thd, thd->locked_tables,table); - table->locked_by_flush=1; // Will be reopened with locks - } + if (morph_locks) + { + /* + Wake up threads waiting for table-level lock on this table + so they won't sneak in when we will temporarily remove our + lock on it. This will also give them a chance to close their + instances of this table. + */ + mysql_lock_abort(thd, table); + mysql_lock_remove(thd, thd->locked_tables, table); + /* + We want to protect the table from concurrent DDL operations + (like RENAME TABLE) until we will re-open and re-lock it. + */ + table->open_placeholder= 1; + } table->file->close(); table->db_stat=0; } + else if (table->open_placeholder) + { + /* + We come here only in close-for-back-off scenario. So we have to + "close" create placeholder here to avoid deadlocks (for example, + in case of concurrent execution of CREATE TABLE t1 SELECT * FROM t2 + and RENAME TABLE t2 TO t1). In close-for-re-open scenario we will + probably want to let it stay. + */ + DBUG_ASSERT(!morph_locks); + table->open_placeholder= 0; + } } } if (found) @@ -1923,9 +2280,8 @@ bool table_is_used(TABLE *table, bool wait_for_name_lock) search= (TABLE*) hash_next(&open_cache, (byte*) key, key_length, &state)) { - if (search->locked_by_flush || - search->locked_by_name && wait_for_name_lock || - search->db_stat && search->s->version < refresh_version) + if (search->locked_by_name && wait_for_name_lock || + search->is_name_opened() && search->needs_reopen_or_name_lock()) return 1; // Table is used } } while ((table=table->next)); @@ -5661,7 +6017,7 @@ bool remove_table_from_cache(THD *thd, const char *db, const char *table_name, else if (in_use != thd) { in_use->some_tables_deleted=1; - if (table->db_stat) + if (table->is_name_opened()) { DBUG_PRINT("info", ("Found another active instance of the table")); result=1; diff --git a/sql/sql_handler.cc b/sql/sql_handler.cc index d1a5ab7dfa8..e1318aa2736 100644 --- a/sql/sql_handler.cc +++ b/sql/sql_handler.cc @@ -670,7 +670,7 @@ int mysql_ha_flush(THD *thd, TABLE_LIST *tables, uint mode_flags, while (*table_ptr) { if ((mode_flags & MYSQL_HA_FLUSH_ALL) || - ((*table_ptr)->s->version != refresh_version)) + (*table_ptr)->needs_reopen_or_name_lock()) { /* The first time it is required, lock for close_thread_table(). */ if (! did_lock && ! is_locked) @@ -771,15 +771,22 @@ void mysql_ha_mark_tables_for_reopen(THD *thd, TABLE *table) safe_mutex_assert_owner(&LOCK_open); for (; table; table= table->next) { - TABLE_LIST *hash_tables; - if ((hash_tables= (TABLE_LIST*) hash_search(&thd->handler_tables_hash, - (byte*) table->alias, - strlen(table->alias) + 1))) + /* + Some elements in open table list, for example placeholders used for + name-locking, can have alias set to 0. + */ + if (table->alias) { - /* Mark table as ready for reopen. */ - hash_tables->table= NULL; - /* End open index/table scans. */ - table->file->ha_index_or_rnd_end(); + TABLE_LIST *hash_tables; + if ((hash_tables= (TABLE_LIST*) hash_search(&thd->handler_tables_hash, + (byte*) table->alias, + strlen(table->alias) + 1))) + { + /* Mark table as ready for reopen. */ + hash_tables->table= NULL; + /* End open index/table scans. */ + table->file->ha_index_or_rnd_end(); + } } } DBUG_VOID_RETURN; diff --git a/sql/sql_insert.cc b/sql/sql_insert.cc index f1d86224adb..4ba820ddefd 100644 --- a/sql/sql_insert.cc +++ b/sql/sql_insert.cc @@ -2179,7 +2179,7 @@ bool delayed_insert::handle_inserts(void) thd.proc_info="insert"; max_rows= delayed_insert_limit; - if (thd.killed || table->s->version != refresh_version) + if (thd.killed || table->needs_reopen_or_name_lock()) { thd.killed= THD::KILL_CONNECTION; max_rows= ~(ulong)0; // Do as much as possible @@ -2791,8 +2791,8 @@ bool select_insert::send_eof() ***************************************************************************/ /* - Create table from lists of fields and items (or open existing table - with same name). + Create table from lists of fields and items (or just return TABLE + object for pre-opened existing table). SYNOPSIS create_table_from_items() @@ -2807,18 +2807,24 @@ bool select_insert::send_eof() of fields for the table (corresponding fields will be added to the end of alter_info->create_list) lock out Pointer to the MYSQL_LOCK object for table created - (open) will be returned in this parameter. Since - this table is not included in THD::lock caller is - responsible for explicitly unlocking this table. + (or open temporary table) will be returned in this + parameter. Since this table is not included in + THD::lock caller is responsible for explicitly + unlocking this table. NOTES - If 'create_info->options' bitmask has HA_LEX_CREATE_IF_NOT_EXISTS - flag and table with name provided already exists then this function will - simply open existing table. - Also note that create, open and lock sequence in this function is not - atomic and thus contains gap for deadlock and can cause other troubles. - Since this function contains some logic specific to CREATE TABLE ... SELECT - it should be changed before it can be used in other contexts. + This function behaves differently for base and temporary tables: + - For base table we assume that either table exists and was pre-opened + and locked at open_and_lock_tables() stage (and in this case we just + emit error or warning and return pre-opened TABLE object) or special + placeholder was put in table cache that guarantees that this table + won't be created or opened until the placeholder will be removed + (so there is an exclusive lock on this table). + - We don't pre-open existing temporary table, instead we either open + or create and then open table in this function. + + Since this function contains some logic specific to CREATE TABLE ... + SELECT it should be changed before it can be used in other contexts. RETURN VALUES non-zero Pointer to TABLE object for table created or opened @@ -2841,6 +2847,25 @@ static TABLE *create_table_from_items(THD *thd, HA_CREATE_INFO *create_info, bool not_used; DBUG_ENTER("create_table_from_items"); + DBUG_EXECUTE_IF("sleep_create_select_before_check_if_exists", my_sleep(6000000);); + + if (!(create_info->options & HA_LEX_CREATE_TMP_TABLE) && + create_table->table->db_stat) + { + /* Table already exists and was open at open_and_lock_tables() stage. */ + if (create_info->options & HA_LEX_CREATE_IF_NOT_EXISTS) + { + create_info->table_existed= 1; // Mark that table existed + push_warning_printf(thd, MYSQL_ERROR::WARN_LEVEL_NOTE, + ER_TABLE_EXISTS_ERROR, ER(ER_TABLE_EXISTS_ERROR), + create_table->table_name); + DBUG_RETURN(create_table->table); + } + + my_error(ER_TABLE_EXISTS_ERROR, MYF(0), create_table->table_name); + DBUG_RETURN(0); + } + tmp_table.alias= 0; tmp_table.timestamp_field= 0; tmp_table.s= &tmp_table.share_not_to_be_used; @@ -2869,8 +2894,15 @@ static TABLE *create_table_from_items(THD *thd, HA_CREATE_INFO *create_info, cr_field->flags &= ~NOT_NULL_FLAG; alter_info->create_list.push_back(cr_field); } + + DBUG_EXECUTE_IF("sleep_create_select_before_create", my_sleep(6000000);); + /* - create and lock table + Create and lock table. + + Note that we either creating (or opening existing) temporary table or + creating base table on which name we have exclusive lock. So code below + should not cause deadlocks or races. We don't log the statement, it will be logged later. @@ -2880,59 +2912,70 @@ static TABLE *create_table_from_items(THD *thd, HA_CREATE_INFO *create_info, don't want to delete from it) 2) it would be written before the CREATE TABLE, which is a wrong order. So we keep binary logging disabled when we open_table(). - NOTE: By locking table which we just have created (or for which we just have - have found that it already exists) separately from other tables used by the - statement we create potential window for deadlock. - TODO: create and open should be done atomic ! */ { tmp_disable_binlog(thd); if (!mysql_create_table(thd, create_table->db, create_table->table_name, create_info, alter_info, 0, select_field_count)) { - /* - If we are here in prelocked mode we either create temporary table - or prelocked mode is caused by the SELECT part of this statement. - */ - DBUG_ASSERT(!thd->prelocked_mode || - create_info->options & HA_LEX_CREATE_TMP_TABLE || - thd->lex->requires_prelocking()); - /* - NOTE: We don't want to ignore set of locked tables here if we are - under explicit LOCK TABLES since it will open gap for deadlock - too wide (and also is not backward compatible). - */ - if (! (table= open_table(thd, create_table, thd->mem_root, (bool*) 0, - (MYSQL_LOCK_IGNORE_FLUSH | - ((thd->prelocked_mode == PRELOCKED) ? - MYSQL_OPEN_IGNORE_LOCKED_TABLES:0))))) - quick_rm_table(create_info->db_type, create_table->db, - table_case_name(create_info, create_table->table_name)); + if (create_info->table_existed && + !(create_info->options & HA_LEX_CREATE_TMP_TABLE)) + { + /* + This means that someone created table underneath server + or it was created via different mysqld front-end to the + cluster. We don't have much options but throw an error. + */ + my_error(ER_TABLE_EXISTS_ERROR, MYF(0), create_table->table_name); + DBUG_RETURN(0); + } + + DBUG_EXECUTE_IF("sleep_create_select_before_open", my_sleep(6000000);); + + if (!(create_info->options & HA_LEX_CREATE_TMP_TABLE)) + { + VOID(pthread_mutex_lock(&LOCK_open)); + if (reopen_name_locked_table(thd, create_table, FALSE)) + { + quick_rm_table(create_info->db_type, create_table->db, + table_case_name(create_info, + create_table->table_name)); + } + else + table= create_table->table; + VOID(pthread_mutex_unlock(&LOCK_open)); + } + else + { + if (!(table= open_table(thd, create_table, thd->mem_root, (bool*) 0, + MYSQL_OPEN_TEMPORARY_ONLY)) && + !create_info->table_existed) + { + /* + This shouldn't happen as creation of temporary table should make + it preparable for open. But let us do close_temporary_table() here + just in case. + */ + close_temporary_table(thd, create_table->db, create_table->table_name); + } + } } reenable_binlog(thd); if (!table) // open failed DBUG_RETURN(0); } - /* - FIXME: What happens if trigger manages to be created while we are - obtaining this lock ? May be it is sensible just to disable - trigger execution in this case ? Or will MYSQL_LOCK_IGNORE_FLUSH - save us from that ? - */ + DBUG_EXECUTE_IF("sleep_create_select_before_lock", my_sleep(6000000);); + table->reginfo.lock_type=TL_WRITE; if (! ((*lock)= mysql_lock_tables(thd, &table, 1, MYSQL_LOCK_IGNORE_FLUSH, ¬_used))) { - VOID(pthread_mutex_lock(&LOCK_open)); - hash_delete(&open_cache,(byte*) table); - VOID(pthread_mutex_unlock(&LOCK_open)); - quick_rm_table(create_info->db_type, create_table->db, - table_case_name(create_info, create_table->table_name)); + if (!create_info->table_existed) + drop_open_table(thd, table, create_table->db, create_table->table_name); DBUG_RETURN(0); } - table->file->extra(HA_EXTRA_WRITE_CACHE); DBUG_RETURN(table); } @@ -2983,8 +3026,10 @@ select_create::prepare(List<Item> &values, SELECT_LEX_UNIT *u) (thd->variables.sql_mode & (MODE_STRICT_TRANS_TABLES | MODE_STRICT_ALL_TABLES))); - DBUG_RETURN(check_that_all_fields_are_given_values(thd, table, - table_list)); + if (check_that_all_fields_are_given_values(thd, table, table_list)) + DBUG_RETURN(1); + table->file->extra(HA_EXTRA_WRITE_CACHE); + DBUG_RETURN(0); } @@ -3016,31 +3061,18 @@ bool select_create::send_eof() { table->file->extra(HA_EXTRA_NO_IGNORE_DUP_KEY); table->file->extra(HA_EXTRA_WRITE_CANNOT_REPLACE); - VOID(pthread_mutex_lock(&LOCK_open)); - mysql_unlock_tables(thd, lock); - /* - TODO: - Check if we can remove the following two rows. - We should be able to just keep the table in the table cache. - */ - if (!table->s->tmp_table) + if (lock) { - ulong version= table->s->version; - hash_delete(&open_cache,(byte*) table); - /* Tell threads waiting for refresh that something has happened */ - if (version != refresh_version) - broadcast_refresh(); + mysql_unlock_tables(thd, lock); + lock= 0; } - lock=0; - table=0; - VOID(pthread_mutex_unlock(&LOCK_open)); } return tmp; } + void select_create::abort() { - VOID(pthread_mutex_lock(&LOCK_open)); if (lock) { mysql_unlock_tables(thd, lock); @@ -3050,22 +3082,10 @@ void select_create::abort() { table->file->extra(HA_EXTRA_NO_IGNORE_DUP_KEY); table->file->extra(HA_EXTRA_WRITE_CANNOT_REPLACE); - enum db_type table_type=table->s->db_type; - if (!table->s->tmp_table) - { - ulong version= table->s->version; - hash_delete(&open_cache,(byte*) table); - if (!create_info->table_existed) - quick_rm_table(table_type, create_table->db, create_table->table_name); - /* Tell threads waiting for refresh that something has happened */ - if (version != refresh_version) - broadcast_refresh(); - } - else if (!create_info->table_existed) - close_temporary_table(thd, create_table->db, create_table->table_name); + if (!create_info->table_existed) + drop_open_table(thd, table, create_table->db, create_table->table_name); table=0; } - VOID(pthread_mutex_unlock(&LOCK_open)); } diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc index 30abb7c2c0a..4ce0dc43144 100644 --- a/sql/sql_parse.cc +++ b/sql/sql_parse.cc @@ -3014,7 +3014,13 @@ mysql_execute_command(THD *thd) select_lex->options|= SELECT_NO_UNLOCK; unit->set_limit(select_lex); - if (!(res= open_and_lock_tables(thd, select_tables))) + if (!(lex->create_info.options & HA_LEX_CREATE_TMP_TABLE)) + { + lex->link_first_table_back(create_table, link_to_local); + create_table->create= TRUE; + } + + if (!(res= open_and_lock_tables(thd, lex->query_tables))) { /* Is table which we are changing used somewhere in other parts @@ -3023,6 +3029,7 @@ mysql_execute_command(THD *thd) if (!(create_info.options & HA_LEX_CREATE_TMP_TABLE)) { TABLE_LIST *duplicate; + create_table= lex->unlink_first_table(&link_to_local); if ((duplicate= unique_table(thd, create_table, select_tables, 0))) { update_non_unique_table_error(create_table, "CREATE", duplicate); @@ -3066,6 +3073,9 @@ mysql_execute_command(THD *thd) delete sel_result; } } + else if (!(lex->create_info.options & HA_LEX_CREATE_TMP_TABLE)) + create_table= lex->unlink_first_table(&link_to_local); + } else { diff --git a/sql/sql_prepare.cc b/sql/sql_prepare.cc index d3cc3613b4a..fcd70ad92ff 100644 --- a/sql/sql_prepare.cc +++ b/sql/sql_prepare.cc @@ -1491,8 +1491,21 @@ static bool mysql_test_create_table(Prepared_statement *stmt) if (select_lex->item_list.elements) { + if (!(lex->create_info.options & HA_LEX_CREATE_TMP_TABLE)) + { + lex->link_first_table_back(create_table, link_to_local); + create_table->create= TRUE; + } + + if (open_and_lock_tables(stmt->thd, lex->query_tables)) + DBUG_RETURN(TRUE); + + if (!(lex->create_info.options & HA_LEX_CREATE_TMP_TABLE)) + create_table= lex->unlink_first_table(&link_to_local); + select_lex->context.resolve_in_select_list= TRUE; - res= select_like_stmt_test_with_open_n_lock(stmt, tables, 0, 0); + + res= select_like_stmt_test(stmt, 0, 0); } /* put tables back for PS rexecuting */ diff --git a/sql/sql_table.cc b/sql/sql_table.cc index 42d59a10712..079cc0d6456 100644 --- a/sql/sql_table.cc +++ b/sql/sql_table.cc @@ -62,8 +62,8 @@ static void set_tmp_file_path(char *buf, size_t bufsize, THD *thd); # Size of path */ -static uint build_table_path(char *buff, size_t bufflen, const char *db, - const char *table, const char *ext) +uint build_table_path(char *buff, size_t bufflen, const char *db, + const char *table, const char *ext) { strxnmov(buff, bufflen-1, mysql_data_home, "/", db, "/", table, ext, NullS); @@ -1722,7 +1722,14 @@ bool mysql_create_table(THD *thd,const char *db, const char *table_name, VOID(pthread_mutex_lock(&LOCK_open)); if (!internal_tmp_table && !(create_info->options & HA_LEX_CREATE_TMP_TABLE)) { - if (!access(path,F_OK)) + /* + Inspecting table cache for placeholders created by concurrent + CREATE TABLE ... SELECT statements to avoid interfering with them + is 5.0-only solution. Starting from 5.1 we solve this problem by + obtaining name-lock on the table to be created first. + */ + if (table_cache_has_open_placeholder(thd, db, table_name) || + !access(path, F_OK)) { if (create_info->options & HA_LEX_CREATE_IF_NOT_EXISTS) goto warn; @@ -2051,7 +2058,7 @@ static int prepare_for_restore(THD* thd, TABLE_LIST* table, to finish the restore in the handler later on */ pthread_mutex_lock(&LOCK_open); - if (reopen_name_locked_table(thd, table)) + if (reopen_name_locked_table(thd, table, TRUE)) { unlock_table_name(thd, table); pthread_mutex_unlock(&LOCK_open); @@ -2158,7 +2165,7 @@ static int prepare_for_repair(THD* thd, TABLE_LIST *table_list, to finish the repair in the handler later on. */ pthread_mutex_lock(&LOCK_open); - if (reopen_name_locked_table(thd, table_list)) + if (reopen_name_locked_table(thd, table_list, TRUE)) { unlock_table_name(thd, table_list); pthread_mutex_unlock(&LOCK_open); @@ -2803,10 +2810,24 @@ bool mysql_create_like_table(THD* thd, TABLE_LIST* table, } else { + bool exists; strxmov(dst_path, mysql_data_home, "/", db, "/", table_name, reg_ext, NullS); fn_format(dst_path, dst_path, "", "", MYF(MY_UNPACK_FILENAME)); - if (!access(dst_path, F_OK)) + + /* + Note that this critical section should actually cover most + of mysql_create_like_table() function. See bugs #18950 and + #23667 for more information. + Also note that starting from 5.1 we obtain name-lock on + target table instead of inspecting table cache for presence + of open placeholders (see comment in mysql_create_table()). + */ + pthread_mutex_lock(&LOCK_open); + exists= (table_cache_has_open_placeholder(thd, db, table_name) || + !access(dst_path, F_OK)); + pthread_mutex_unlock(&LOCK_open); + if (exists) goto table_exists; } @@ -3160,9 +3181,14 @@ view_err: else { char dir_buff[FN_REFLEN]; + bool exists; strxnmov(dir_buff, FN_REFLEN, mysql_real_data_home, new_db, NullS); - if (!access(fn_format(new_name_buff,new_name_buff,dir_buff,reg_ext,0), - F_OK)) + VOID(pthread_mutex_lock(&LOCK_open)); + exists= (table_cache_has_open_placeholder(thd, new_db, new_name) || + !access(fn_format(new_name_buff, new_name_buff, dir_buff, + reg_ext, 0), F_OK)); + VOID(pthread_mutex_unlock(&LOCK_open)); + if (exists) { /* Table will be closed in do_command() */ my_error(ER_TABLE_EXISTS_ERROR, MYF(0), new_alias); @@ -3247,8 +3273,22 @@ view_err: if (!error && (new_name != table_name || new_db != db)) { thd->proc_info="rename"; - /* Then do a 'simple' rename of the table */ - if (!access(new_name_buff,F_OK)) + /* + Then do a 'simple' rename of the table. First we need to close all + instances of 'source' table. + */ + close_cached_table(thd, table); + /* + Then, we want check once again that target table does not exist. + Note that we can't fully rely on results of previous check since + no lock was taken on target table during it. We also can't do this + before calling close_cached_table() as the latter temporarily + releases LOCK_open mutex. + Also note that starting from 5.1 we use approach with obtaining + of name-lock on target table. + */ + if (table_cache_has_open_placeholder(thd, new_db, new_name) || + !access(new_name_buff,F_OK)) { my_error(ER_TABLE_EXISTS_ERROR, MYF(0), new_name); error= -1; @@ -3256,7 +3296,6 @@ view_err: else { *fn_ext(new_name)=0; - close_cached_table(thd, table); if (mysql_rename_table(old_db_type,db,table_name,new_db,new_alias)) error= -1; else if (Table_triggers_list::change_table_name(thd, db, table_name, @@ -3806,17 +3845,6 @@ view_err: current_pid, thd->thread_id); if (lower_case_table_names) my_casedn_str(files_charset_info, old_name); - if (new_name != table_name || new_db != db) - { - if (!access(new_name_buff,F_OK)) - { - error=1; - my_error(ER_TABLE_EXISTS_ERROR, MYF(0), new_name_buff); - VOID(quick_rm_table(new_db_type,new_db,tmp_name)); - VOID(pthread_mutex_unlock(&LOCK_open)); - goto err; - } - } #if (!defined( __WIN__) && !defined( __EMX__) && !defined( OS2)) if (table->file->has_transactions()) @@ -3835,6 +3863,22 @@ view_err: table->file->extra(HA_EXTRA_FORCE_REOPEN); // Don't use this file anymore #endif + if (new_name != table_name || new_db != db) + { + /* + Check that there is no table with target name. See the + comment describing code for 'simple' ALTER TABLE ... RENAME. + */ + if (table_cache_has_open_placeholder(thd, new_db, new_name) || + !access(new_name_buff,F_OK)) + { + error=1; + my_error(ER_TABLE_EXISTS_ERROR, MYF(0), new_name_buff); + VOID(quick_rm_table(new_db_type,new_db,tmp_name)); + VOID(pthread_mutex_unlock(&LOCK_open)); + goto err; + } + } error=0; if (!need_copy_table) diff --git a/sql/sql_trigger.cc b/sql/sql_trigger.cc index 26b557a8247..cf6db22fbcb 100644 --- a/sql/sql_trigger.cc +++ b/sql/sql_trigger.cc @@ -271,7 +271,7 @@ bool mysql_create_or_drop_trigger(THD *thd, TABLE_LIST *tables, bool create) /* We also don't allow creation of triggers on views. */ tables->required_type= FRMTYPE_TABLE; - if (reopen_name_locked_table(thd, tables)) + if (reopen_name_locked_table(thd, tables, TRUE)) { unlock_table_name(thd, tables); goto end; diff --git a/sql/sql_yacc.yy b/sql/sql_yacc.yy index 390a991c7b6..12d35d5edd3 100644 --- a/sql/sql_yacc.yy +++ b/sql/sql_yacc.yy @@ -1489,9 +1489,7 @@ create: lex->sql_command= SQLCOM_CREATE_TABLE; if (!lex->select_lex.add_table_to_list(thd, $5, NULL, TL_OPTION_UPDATING, - (using_update_log ? - TL_READ_NO_INSERT: - TL_READ))) + TL_WRITE)) MYSQL_YYABORT; lex->alter_info.reset(); lex->col_list.empty(); diff --git a/sql/table.h b/sql/table.h index 61232a39f0e..da2c90ab212 100644 --- a/sql/table.h +++ b/sql/table.h @@ -188,6 +188,8 @@ typedef struct st_table_share } TABLE_SHARE; +extern ulong refresh_version; + /* Information for one open table */ struct st_table { @@ -268,7 +270,24 @@ struct st_table { my_bool force_index; my_bool distinct,const_table,no_rows; my_bool key_read, no_keyread; - my_bool locked_by_flush; + /* + Placeholder for an open table which prevents other connections + from taking name-locks on this table. Typically used with + TABLE_SHARE::version member to take an exclusive name-lock on + this table name -- a name lock that not only prevents other + threads from opening the table, but also blocks other name + locks. This is achieved by: + - setting open_placeholder to 1 - this will block other name + locks, as wait_for_locked_table_name will be forced to wait, + see table_is_used for details. + - setting version to 0 - this will force other threads to close + the instance of this table and wait (this is the same approach + as used for usual name locks). + An exclusively name-locked table currently can have no handler + object associated with it (db_stat is always 0), but please do + not rely on that. + */ + my_bool open_placeholder; my_bool locked_by_name; my_bool fulltext_searched; my_bool no_cache; @@ -291,6 +310,13 @@ struct st_table { bool fill_item_list(List<Item> *item_list) const; void reset_item_list(List<Item> *item_list) const; + /* Is table open or should be treated as such by name-locking? */ + inline bool is_name_opened() { return db_stat || open_placeholder; } + /* + Is this instance of the table should be reopen or represents a name-lock? + */ + inline bool needs_reopen_or_name_lock() + { return s->version != refresh_version; } }; enum enum_schema_table_state @@ -648,6 +674,12 @@ typedef struct st_table_list used for implicit LOCK TABLES only and won't be used in real statement. */ bool prelocking_placeholder; + /* + This TABLE_LIST object corresponds to the table to be created + so it is possible that it does not exist (used in CREATE TABLE + ... SELECT implementation). + */ + bool create; enum enum_schema_table_state schema_table_state; void calc_md5(char *buffer); @@ -655,7 +687,11 @@ typedef struct st_table_list int view_check_option(THD *thd, bool ignore_failure); bool setup_underlying(THD *thd); void cleanup_items(); - bool placeholder() {return derived || view || schema_table || !table; } + bool placeholder() + { + return derived || view || schema_table || create && !table->db_stat || + !table; + } void print(THD *thd, String *str); bool check_single_table(st_table_list **table, table_map map, st_table_list *view); |