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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. Note that we have separate fix for 5.0 since there we use slightly different less intrusive approach. mysql-test/r/create.result: Extended test coverage for CREATE TABLE ... SELECT. In particular added tests for bug #24508 "Inconsistent results of CREATE TABLE ... SELECT when temporary table exists" and bug #20662 "Infinite loop in CREATE TABLE IF NOT EXISTS ... SELECT with locked tables". mysql-test/r/trigger.result: Added test case for bug #20903 "Crash when using CREATE TABLE .. SELECT and triggers" mysql-test/t/create.test: Extended test coverage for CREATE TABLE ... SELECT. In particular added tests for bug #24508 "Inconsistent results of CREATE TABLE ... SELECT when temporary table exists" and bug #20662 "Infinite loop in CREATE TABLE IF NOT EXISTS ... SELECT with locked tables". mysql-test/t/trigger.test: Added test case for bug #20903 "Crash when using CREATE TABLE .. SELECT and triggers" sql/lock.cc: Now for creation of name-lock placeholder lock_table_name() uses auxiliary function table_cache_insert_placeholder(). sql/mysql_priv.h: Removed declaration of non-existing build_table_path() routine. The former mysql_create_table_internal() was renamed to mysql_create_table_no_lock() and now exposed to other modules to give them opportunity of creation of tables in cases when name-lock is already obtained. reopen_name_locked_table() now has 3rd argument which controls linking in of table being opened into THD::open_tables (this is useful in cases when placeholder used for name-locking is already linked into this list). Added declaration of auxiliary function table_cache_insert_placeholder() which is used for creation of table placeholders for name-locking. Added declaration of lock_table_name_if_not_cached() which can be used to take an exclusive name-lock on table if there are no records for it in table cache. Changed signature of unlink_open_table() function to simplify its use and make it useful for table placeholders and tables that are only open. Added auxiliary drop_open_table() routine. Moved declaration of refresh_version to table.h header to make it accessible from inline methods of TABLE class. MYSQL_OPEN_IGNORE_LOCKED_TABLES flag is no longer used. Instead MYSQL_OPEN_TEMPORARY_ONLY option was added. sql/sql_base.cc: Added support for the new approach to the handling of CREATE TABLE ... SELECT for base tables. Now 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. Note significant distinctions of this placeholder from the placeholder used for normal name-lock: 1) It is treated like open table by other name-locks so it does not allow name-lock taking operations like DROP TABLE or RENAME TABLE to proceed. 2) it is linked into THD::open_tables list and automatically removed during close_thread_tables() call open_tables(): Implemented logic described above. To do this added auxiliary check_if_table_exists() function. Removed support for MYSQL_OPEN_IGNORE_LOCKED_TABLES option which is no longer used. Added MYSQL_OPEN_TEMPORARY_ONLY which is used to restrict search for temporary tables only. close_cached_tables()/close_thread_table()/reopen_tables()/ close_old_data_files()/table_is_used()/remove_table_from_cache(): Added support for open placeholders (note that we also use them when we need to re-open tables during flush). unlink_open_table(): Changed function signature to simplify its use and to make useful for open placeholders and tables which are only open and not locked. Added auxiliary drop_open_table() routine. reopen_name_locked_table(): Now has 3rd argument which controls linking in of table being opened into THD::open_tables (this is useful in cases when placeholder used for name-locking is already linked into this list). Added auxiliary table_cache_insert_placeholder() routine which simplifies creation of placeholders used for name-locking. Added lock_table_name_if_not_cached() which can be used to take an exclusive name-lock on table if there are no records for it in table cache. sql/sql_handler.cc: Adjusted mysql_ha_mark_tables_for_reopen() routine to properly handle placeholders which now can be linked into open tables list. sql/sql_insert.cc: Introduced new approach to handling of base tables in CREATE TABLE ... SELECT statement. Now 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. By doing this we avoid races which existed with previous approach in which we created, opened and locked target in separate step without any special protection. This also allows properly calculate prelocking set in cases when target table already exists and has some on insert triggers. Note that we don't employ the same approach for temporary tables (this is okay as such tables are unaffected by other threads). Changed create_table_from_items() and methods of select_create class to implement this approach. sql/sql_parse.cc: The new approach to handling of CREATE TABLE ... SELECT for base tables assumes that all tables (including table to be created) are opened and (or) locked at the same time. So in cases when we create base table we have to pass to open_and_lock_tables() table list which includes target table. sql/sql_prepare.cc: The new approach to handling of CREATE TABLE ... SELECT for base tables assumes that all tables (including table to be created) are opened and (or) locked at the same time. So in cases when we create base table we have to pass to open_and_lock_tables() table list which includes target table. sql/sql_table.cc: Changed mysql_create_table(), mysql_create_like_table() and mysql_alter_table() (in rename case) to obtain exclusive name-lock on the non-temporary table which is going to be created (to which we going to rename). This ensures that not only destination table doesn't exist on disk but also that there are no placeholder in table cache for it (i.e. there is no CREATE TABLE ... SELECT operation in progress for it). Note that to avoid deadlocks while taking these name-locks this code assumes that existence of any record for table in table cache (even name-lock) means that table exists. Altough such check can lead to false positives these should occur only in case of highly concurrent DDL operations on the table and should not break binary logging. Renamed mysql_create_table_internal() to mysql_create_table_no_lock() and made it accessible from other files to give them ability to create table in situation when name-lock is already obtained or not relevant. Adjusted calls to reopen_name_locked_table(), which now takes extra argument, which controls linking of open table into THD::open_tables list. Removed redundant setting of table's 'version' field before calls to close_cached_table(). This function will set it to 0 itself anyway. sql/sql_trigger.cc: reopen_name_locked_tables() now has one more argument which controls linking of opened table into the THD::open_tables list. sql/sql_yacc.yy: The new approach to handling of CREATE TABLE ... SELECT statement for base tables assumes that all tables including table to be created are open and (or) locked at the same time. Therefore we need to set correct lock for target table. sql/table.h: Moved declaration of refresh_version variable from mysql_priv.h to make it accessible from inline methods of TABLE class. Renamed TABLE::locked_by_flush member to open_placeholder since now it is also used for taking exclusive name-lock and not only by flush. Introduced TABLE::is_name_opened() helper method which can be used to distinguish TABLE instances corresponding to open tables or placeholders for them from closed instances (e.g. due to their old version). Also introduced TABLE::needs_reopen_or_name_lock() helper which allows to check if TABLE instance corresponds to outdated version of table or to name-lock placeholder. Introduced TABLE_LIST::create member which marks elements of table list corresponds to the table to be created. Adjusted TABLE_LIST::placeholder() method to take into account name-lock placeholders for tables to be created (this, for example, allows to properly handle such placeholders in lock_tables()). Finally, moved currently unused TABLE::open_next/open_prev members under ifdef NOT_YET. mysql-test/r/create_select-big.result: New BitKeeper file ``mysql-test/r/create_select-big.result'' mysql-test/t/create_select-big.test: New BitKeeper file ``mysql-test/t/create_select-big.test''
164 lines
3.9 KiB
Text
164 lines
3.9 KiB
Text
drop table if exists t1,t2,t3,t4,t5;
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set session debug="+d,sleep_create_select_before_create";
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create table t1 select 1 as i;;
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create table t1 (j char(5));
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ERROR 42S01: Table 't1' already exists
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show create table t1;
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Table Create Table
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t1 CREATE TABLE `t1` (
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`i` int(1) NOT NULL DEFAULT '0'
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) ENGINE=MyISAM DEFAULT CHARSET=latin1
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drop table t1;
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create table t1 select 1 as i;;
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create table t1 select "Test" as j;
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ERROR 42S01: Table 't1' already exists
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show create table t1;
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Table Create Table
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t1 CREATE TABLE `t1` (
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`i` int(1) NOT NULL DEFAULT '0'
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) ENGINE=MyISAM DEFAULT CHARSET=latin1
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drop table t1;
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create table t3 (j char(5));
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create table t1 select 1 as i;;
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create table t1 like t3;
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ERROR 42S01: Table 't1' already exists
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show create table t1;
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Table Create Table
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t1 CREATE TABLE `t1` (
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`i` int(1) NOT NULL DEFAULT '0'
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) ENGINE=MyISAM DEFAULT CHARSET=latin1
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drop table t1;
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create table t1 select 1 as i;;
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rename table t3 to t1;
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ERROR 42S01: Table 't1' already exists
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show create table t1;
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Table Create Table
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t1 CREATE TABLE `t1` (
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`i` int(1) NOT NULL DEFAULT '0'
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) ENGINE=MyISAM DEFAULT CHARSET=latin1
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drop table t1;
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create table t1 select 1 as i;;
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alter table t3 rename to t1;
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ERROR 42S01: Table 't1' already exists
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show create table t1;
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Table Create Table
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t1 CREATE TABLE `t1` (
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`i` int(1) NOT NULL DEFAULT '0'
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) ENGINE=MyISAM DEFAULT CHARSET=latin1
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drop table t1;
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create table t1 select 1 as i;;
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alter table t3 rename to t1, add k int;
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ERROR 42S01: Table 't1' already exists
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show create table t1;
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Table Create Table
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t1 CREATE TABLE `t1` (
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`i` int(1) NOT NULL DEFAULT '0'
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) ENGINE=MyISAM DEFAULT CHARSET=latin1
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drop table t1, t3;
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set session debug="-d,sleep_create_select_before_create:+d,sleep_create_select_before_open";
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create table t1 select 1 as i;;
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drop table t1;
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create table t1 select 1 as i;;
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rename table t1 to t2;
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drop table t2;
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create table t1 select 1 as i;;
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select * from t1;
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i
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1
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drop table t1;
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create table t1 select 1 as i;;
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insert into t1 values (2);
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select * from t1;
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i
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1
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2
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drop table t1;
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set @a:=0;
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create table t1 select 1 as i;;
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create trigger t1_bi before insert on t1 for each row set @a:=1;
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select @a;
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@a
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0
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drop table t1;
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set session debug="-d,sleep_create_select_before_open:+d,sleep_create_select_before_lock";
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create table t1 select 1 as i;;
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drop table t1;
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create table t1 select 1 as i;;
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rename table t1 to t2;
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drop table t2;
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create table t1 select 1 as i;;
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select * from t1;
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i
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1
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drop table t1;
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create table t1 select 1 as i;;
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insert into t1 values (2);
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select * from t1;
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i
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1
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2
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drop table t1;
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set @a:=0;
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create table t1 select 1 as i;;
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create trigger t1_bi before insert on t1 for each row set @a:=1;
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select @a;
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@a
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0
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drop table t1;
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set session debug="-d,sleep_create_select_before_lock:+d,sleep_create_select_before_check_if_exists";
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create table t1 (i int);
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create table if not exists t1 select 1 as i;;
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drop table t1;
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Warnings:
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Note 1050 Table 't1' already exists
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create table t1 (i int);
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set @a:=0;
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create table if not exists t1 select 1 as i;;
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create trigger t1_bi before insert on t1 for each row set @a:=1;
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Warnings:
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Note 1050 Table 't1' already exists
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select @a;
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@a
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0
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select * from t1;
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i
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1
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drop table t1;
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set session debug="-d,sleep_create_select_before_check_if_exists";
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create table t2 (a int);
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create table t4 (b int);
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lock table t4 write;
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select 1;
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1
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1
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create table t3 as select * from t4;;
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create table t1 select * from t2, t3;;
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unlock tables;
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select * from t1;
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a b
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show create table t1;
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Table Create Table
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t1 CREATE TABLE `t1` (
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`a` int(11) DEFAULT NULL,
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`b` int(11) DEFAULT NULL
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) ENGINE=MyISAM DEFAULT CHARSET=latin1
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drop table t1, t3;
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lock table t4 read;
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select 1;
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1
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1
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rename table t4 to t3;;
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create table if not exists t1 select 1 as i from t2, t3;;
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create table t5 (j int);
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rename table t5 to t1;
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unlock tables;
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Warnings:
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Note 1050 Table 't1' already exists
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select * from t1;
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j
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show create table t1;
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Table Create Table
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t1 CREATE TABLE `t1` (
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`j` int(11) DEFAULT NULL
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) ENGINE=MyISAM DEFAULT CHARSET=latin1
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drop table t1, t2, t3;
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