VLDB and Partitioning Guide 读书摘要

最新推荐文章于 2025-09-06 22:56:13 发布

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最新推荐文章于 2025-09-06 22:56:13 发布

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原文链接：https://yq.aliyun.com/articles/294239

本文详细介绍了全球索引分区的基本概念、关键属性及维护方法。包括如何处理最高分区的删除、理解全局索引的独特性和非独特性、维护全球索引的优势、创建位图索引的限制、静态和动态修剪的概念、以及创建唯一本地位图索引的条件。此外，还阐述了索引分区规则、创建唯一局部索引的可能以及不同类型的索引和表之间的兼容性。

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