SET GLOBAL innodb_fast_shutdown=0;
# restart: --innodb_undo_tablespaces=2
SET GLOBAL innodb_undo_log_truncate = 0;
=== information_schema.innodb_sys_tablespaces and innodb_sys_datafiles ===
Space_Name	Page_Size	Zip_Size	Path
innodb_undo001	DEFAULT	DEFAULT	MYSQLD_DATADIR//undo001
innodb_undo002	DEFAULT	DEFAULT	MYSQLD_DATADIR//undo002
innodb_temporary	DEFAULT	DEFAULT	MYSQLD_DATADIR/ibtmp1
create table t1(keyc int primary key, c char(100)) engine = innodb;
create table t2(keyc int primary key, c char(100)) engine = innodb;
connect  con1,localhost,root,,;
begin;
insert into t1 select seq,'a' from seq_1_to_20000;
connect  con2,localhost,root,,;
begin;
insert into t2 select seq,'a' from seq_1_to_20000;
connection con1;
update t1 set c = 'mysql';
connection con2;
update t2 set c = 'mysql';
connection con1;
update t1 set c = 'oracle';
connection con2;
update t2 set c = 'oracle';
connection con1;
delete from t1;
connection con2;
delete from t2;
connection con1;
SET GLOBAL innodb_max_undo_log_size = @@GLOBAL.innodb_page_size * 4294967296;
SET GLOBAL innodb_undo_log_truncate = 1;
commit;
disconnect con1;
connection con2;
commit;
disconnect con2;
connection default;
SET GLOBAL innodb_max_purge_lag_wait=0;
SET GLOBAL innodb_max_undo_log_size=DEFAULT;
SET GLOBAL innodb_max_purge_lag_wait=0;
set global innodb_fast_shutdown=0;
# restart
drop table t1, t2;