Oracle教程 2023-02-24

Oracle 视图 DBA_OBJECT_SIZE 官方解释，作用，如何使用详细说明

Oracle视图DBA_OBJECT_SIZE用于显示当前数据库中对象（表，索引，视图等）的大小信息。它通常在DBA为优化数据库性能而进行性能分析时被使用。

使用DBA_OBJECT_SIZE有以下几个步骤：

1. 连接到数据库并打开一个SQL命令提示符窗口

2. 使用 SELECT 语句从 DBA_OBJECT_SIZE 视图中检索数据库对象的大小信息，如：

SELECT segment_name, segment_type, bytes/1024/1024 AS MB FROM dba_segments;

3. 可以使用 ORDER BY 子句根据对象大小对查询结果排序，例如：

SELECT segment_name, segment_type, bytes/1024/1024 AS MB FROM dba_segments ORDER BY MB DESC;

4. 同样可以使用 WHERE 子句只查询特定类型的对象，例如：

SELECT segment_name, segment_type, bytes/1024/1024 AS MB FROM dba_segments WHERE segment_type = ‘TABLE’ ORDER BY MB DESC;

通过使用DBA_OBJECT_SIZE来查找要优化的大对象，DBA可以缩小数据库的存储空间并提高数据库性能。

DBA_OBJECT_SIZE lists the sizes, in bytes, of various PL/SQL objects.

Related View

Column	Datatype	NULL	Description
`OWNER`	`VARCHAR2(128)`	`NOT NULL`	Owner of the object
`NAME`	`VARCHAR2(128)`	`NOT NULL`	Name of the object
`TYPE`	`VARCHAR2(18)`		Type of the object: `TYPE, TYPE BODY, TABLE, VIEW, SYNONYM, SEQUENCE, PROCEDURE, FUNCTION, PACKAGE, PACKAGE BODY, JAVA SOURCE, JAVA CLASS` or `JAVA RESOURCE`
`SOURCE_SIZE`	`NUMBER`		Size of the source in bytes. Must be in memory during compilation, or dynamic recompilation.
`PARSED_SIZE`	`NUMBER`		Size of the parsed form of the object, in bytes. Must be in memory when an object is being compiled that references this object.
`CODE_SIZE`	`NUMBER`		Code size, in bytes. Must be in memory when this object is executing.
`ERROR_SIZE`	`NUMBER`		Size of error messages, in bytes. In memory during the compilation of the object when there are compilation errors.