Oracle 11g如何估计所需的临时表空间?
我们对一些表进行了初始批量加载(源和目标都是Oracle11g)。其过程如下:1。截断,2。删除索引(PK和唯一索引),3。批量插入,4。创建索引(同样是PK和唯一索引)。现在我得到了以下错误:Oracle 11g如何估计所需的临时表空间?,oracle,oracle11g,Oracle,Oracle11g,我们对一些表进行了初始批量加载(源和目标都是Oracle11g)。其过程如下:1。截断,2。删除索引(PK和唯一索引),3。批量插入,4。创建索引(同样是PK和唯一索引)。现在我得到了以下错误: alter table TARGET_SCHEMA.MYBIGTABLE add constraint PK_MYBIGTABLE primary key (MYBIGTABLE_PK) ORA-01652: unable to extend temp segment by 128 in tablesp
alter table TARGET_SCHEMA.MYBIGTABLE
add constraint PK_MYBIGTABLE primary key (MYBIGTABLE_PK)
ORA-01652: unable to extend temp segment by 128 in tablespace TEMP
显然,临时表空间对于PK创建来说太小了(仅供参考,该表有6列,约22亿条记录)。所以我这样做了:
explain plan for
select line_1,line_2,line_3,line_4,line_5,line_6,count(*) as cnt
from SOURCE_SCHEMA.MYBIGTABLE
group by line_1,line_2,line_3,line_4,line_5,line_6;
select * from table( dbms_xplan.display );
/*
-----------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes |TempSpc| Cost (%CPU)| Time |
-----------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 2274M| 63G| | 16M (2)| 00:05:06 |
| 1 | HASH GROUP BY | | 2274M| 63G| 102G| 16M (2)| 00:05:06 |
| 2 | TABLE ACCESS FULL| MYBIGTABLE | 2274M| 63G| | 744K (7)| 00:00:14 |
-----------------------------------------------------------------------------------------------
*/
这是如何判断PK创建需要多少临时表空间(在我的例子中是102 GB)?或者你会做出不同的估计
附加:PK仅存在于目标系统上。但公平点,所以我对目标PK运行您的查询:
explain plan for
select MYBIGTABLE_PK
from TARGET_SCHEMA.MYBIGTABLE
group by MYBIGTABLE_PK ;
-------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
-------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 13 | 3 (34)| 00:00:01 |
| 1 | HASH GROUP BY | | 1 | 13 | 3 (34)| 00:00:01 |
| 2 | TABLE ACCESS FULL| MYBIGTABLE | 1 | 13 | 2 (0)| 00:00:01 |
-------------------------------------------------------------------------------------------
那我现在该怎么读呢?这是个好问题 首先,如果您创建以下主键
alter table TARGET_SCHEMA.MYBIGTABLE
add constraint PK_MYBIGTABLE primary key (MYBIGTABLE_PK)
那么你应该问
explain plan for
select PK_MYBIGTABLE
from SOURCE_SCHEMA.MYBIGTABLE
group by PK_MYBIGTABLE
获取估计值(确保收集统计数据exec dbms\u stats.gather\u table\u stats('SOURCE\u SCHEMA','MYBIGTABLE')
其次,您可以查询V$TEMPSEG_用法
以查看在抛出之前消耗了多少临时块,以及V$session_longops
以查看您完成了多少整个过程
Oracle建议为进程创建一个专用的临时表空间,以避免干扰任何其他操作
如果您找到更准确的解决方案,请发布编辑