1. 首页
  2. IT资讯

VLDB and Partitioning Guide 读书摘要

1、
If a global index partition contains data, dropping the partition causes the next highest partition to be 
marked unusable. You cannot drop the highest partition in a global index.  
p2-14

2、
The highest partition of a global index must have a partition bound, all of whose 
values are MAXVALUE. This ensures that all rows in the underlying table can be 
represented in the index. Global prefixed indexes can be unique or nonunique. 
p2-14

3、
These indexes can be maintained by appending the clause UPDATE INDEXESto the SQL 
statements for the operation. The two advantages to maintaining global indexes:
■ The index remains available and online throughout the operation. Hence no other 
applications are affected by this operation.
■ The index does not have to be rebuilt after the operation.
P2-14

4、
You can create bitmap indexes on partitioned tables, with the restriction that the 
bitmap indexes must be local to the partitioned table. 
P2-15

5、
Static pruning occurs at compile-time, with the information about the 
partitions accessed beforehand. Dynamic pruning occurs at run-time, meaning that the 
exact partitions to be accessed by a statement are not known beforehand. A sample 
scenario for static pruning is a SQL statement containing a WHEREcondition with a 
constant literal on the partition key column. An example of dynamic pruning is the 
use of operators or functions in the WHEREcondition.
P3-2

6、
Oracle Database prunes partitions when you use range, LIKE, equality, and IN-list 
predicates on the range or list partitioning columns, and when you use equality and 
IN-list predicates on the hash partitioning columns
On composite partitioned objects, Oracle Database can prune at both levels using the 
relevant predicates
P3-2

7、
The rules for partitioning indexes are similar to those for tables:
■ An index can be partitioned unless:
– The index is a cluster index.
– The index is defined on a clustered table.
■ You can mix partitioned and nonpartitioned indexes with partitioned and 
nonpartitioned tables:
– A partitioned table can have partitioned or nonpartitioned indexes.
– A nonpartitioned table can have partitioned or nonpartitioned indexes.
■ Bitmap indexes on nonpartitionedtables cannot be partitioned.
■ A bitmap index on a partitioned table must be a local index.

P3-20

8、A local index can be created UNIQUEif the partitioning columns form a subset of the 
index columns
P3-21

来自 “ ITPUB博客 ” ,链接:http://blog.itpub.net/7728585/viewspace-1431326/,如需转载,请注明出处,否则将追究法律责任。

主题测试文章,只做测试使用。发布者:深沉的少年,转转请注明出处:http://www.cxybcw.com/183717.html

联系我们

13687733322

在线咨询:点击这里给我发消息

邮件:1877088071@qq.com

工作时间:周一至周五,9:30-18:30,节假日休息

QR code