DEFERRED_SEGMENT_CREATION

原创于 2021-07-14 13:34:12 发布 · 161 阅读

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本文介绍了Oracle 11g R2中新增的参数deferred_segment_creation，它默认为true，通过避免立即创建不必要的表、索引和分区段，节省资源。文章还讲解了如何设置和使用该参数，并举例说明其在应用安装中的作用和选择不同设定的场景。

Oracle11gR2 新加参数 DEFERRED_SEGMENT_CREATION, 默认TRUE
By default, the database uses deferred segment creation to update only database metadata when creating tables, indexes, and partitions. When a user inserts the first row into a table or partition, the database creates segments for the table or partition, its LOB columns, and its indexes.
Deferred segment creation avoids using database resources unnecessarily. For example, installation of an application can create thousands of objects, consuming significant disk space. Many of these objects may never be used.
Show parameter deferred_segment_creation
也可以在创建segment时声明：
create table scott.t1(id int,name char(10) SEGMENT CREATION IMMEDIATE;
create table scott.t1(id int,name char(10) SEGMENT CREATION DEFERRED;
select table_name, segment_created from user_tables ;