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initrans和maxtrans

原创 Linux操作系统 作者:tolywang 时间:2007-10-19 00:00:00 0 删除 编辑
下面是个测试方法
The interested transaction list is an array that keeps track of (some of) the most recent transactions on a block. The size of this array is specified by the initrans parameter when an object is created. If more entries are needed in the ITL and if there is enough space in the block, the array can grow up to maxtrans.
This can be demonstrated with 3 sessions:
First session;

create table t_ (a number) initrans 1 maxtrans 2;
insert into t_ values (1);
insert into t_ values (2);
insert into t_ values (3);
commit;

update t_ set a = 101 where a = 1;
Second session:
update t_ set a = 102 where a = 2;
Third session:
update t_ set a = 103 where a = 3;
This third session hangs until one of the other session commits or rolls back.

oracle默认initrans就是2,maxtrans是255;initrans可以单独设,maxtrans是要和initrans参数是要同时用的,否则设不成功
10g的maxtrans默认就是255。
select table_name,ini_trans,max_trans from user_tables where table_name ='TNAME'
可看到设置情况

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