SET @save_undo_logs = @@GLOBAL.innodb_undo_logs;
SET @save_frequency = @@GLOBAL.innodb_purge_rseg_truncate_frequency;
SET @save_truncate = @@GLOBAL.innodb_undo_log_truncate;
SET GLOBAL innodb_undo_log_truncate = 0;
SET GLOBAL innodb_purge_rseg_truncate_frequency = 1;
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_undo_log_truncate = 1;
commit;
disconnect con1;
connection con2;
commit;
disconnect con2;
connection default;
SET GLOBAL innodb_purge_rseg_truncate_frequency=1;
SET GLOBAL innodb_max_purge_lag_wait=0;
set global innodb_fast_shutdown=0;
drop table t1, t2;