search
HomeDatabaseMysql TutorialOracle 11g 使用exp命令 导出空表

Oracle11g默认对空表不分配segment,故使用exp导出Oracle11g数据库时,空表不会导出。

1、Oracle11g默认对空表不分配segment,故使用exp导出Oracle11g数据库时,空表不会导出。

2、设置deferred_segment_creation 参数为FALSE后,无论是空表还是非空表,都分配segment。

  在sqlplus中,执行如下命令:

  SQL>alter system set deferred_segment_creation=false;

  查看:
  SQL>show parameter deferred_segment_creation;


  该值设置后只对后面新增的表产生作用,对之前建立的空表不起作用。


3、可以使用手工为空表分配Extent的方式,来解决导出之前建立的空表的问题。说明如下:


3.1 使用ALLOCATE EXTENT的说明


  使用ALLOCATE EXTENT可以为数据库对象分配Extent。其语法如下:

  -----------
  ALLOCATE EXTENT { SIZE integer [K | M] | DATAFILE 'filename' | INSTANCE integer }
  -----------

  可以针对数据表、索引、物化视图等手工分配Extent。

  ALLOCATE EXTENT使用样例:

    ALLOCATE EXTENT
    ALLOCATE EXTENT(SIZE integer [K | M])
    ALLOCATE EXTENT(DATAFILE 'filename')
    ALLOCATE EXTENT(INSTANCE integer)
    ALLOCATE EXTENT(SIZE integer [K | M]  DATAFILE 'filename')
    ALLOCATE EXTENT(SIZE integer [K | M]  INSTANCE integer)
 

    针对数据表操作的完整语法如下:

  -----------
    ALTER TABLE [schema.]table_name ALLOCATE EXTENT [({ SIZE integer [K | M] | DATAFILE 'filename' | INSTANCE integer})]
  -----------


    故,需要构建如下样子简单的SQL命令:

  -----------
  alter table aTabelName allocate extent
  -----------


3.2 构建对空表分配空间的SQL命令,,


    查询当前用户下的所有空表(一个用户最好对应一个默认表空间)。命令如下:

  -----------
  SQL>select table_name from user_tables where NUM_ROWS=0;
  -----------


  根据上述查询,可以构建针对空表分配空间的命令语句,如下:

  -----------
  SQL>Select 'alter table '||table_name||' allocate extent;' from user_tables where num_rows=0
  -----------


  批量输出上述生成的SQL语句,建立C:\createsql.sql,其内容如下:

  -----------
  set heading off;
  set echo off;
  set feedback off;
  set termout on;
  spool C:\allocate.sql;
  Select 'alter table '||table_name||' allocate extent;' from user_tables where num_rows=0;
  spool off;
  -----------


  执行C:\createsql.sql,命令如下:
  -----------
  SQL>@ C:\createsql.sql;
  -----------

  执行完毕后,得到C:\allocate.sql文件。

  打开该文件会看到,已经得到对所有空表分配空间的命令SQL语句。

3.4 执行SQL命令,对空表分配空间:

  执行C:\allocate.sql,命令如下:
  -----------
  SQL>@ C:\allocate.sql;
  -----------
 
  执行完毕,表已更改。

3.4 此时执行exp命令,即可把包括空表在内的所有表,正常导出。

相关阅读:

Linux平台下的Oracle自动备份案例(使用exp工具) 

exp/IMP迁移数据库的时候注释乱码解决方法

Linux下导出数据库dmp文件时exp-00091错误

浅谈Oracle的exp备份问题

EXP/IMP迁移数据

linux

Statement
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
How does MySQL's licensing compare to other database systems?How does MySQL's licensing compare to other database systems?Apr 25, 2025 am 12:26 AM

MySQL uses a GPL license. 1) The GPL license allows the free use, modification and distribution of MySQL, but the modified distribution must comply with GPL. 2) Commercial licenses can avoid public modifications and are suitable for commercial applications that require confidentiality.

When would you choose InnoDB over MyISAM, and vice versa?When would you choose InnoDB over MyISAM, and vice versa?Apr 25, 2025 am 12:22 AM

The situations when choosing InnoDB instead of MyISAM include: 1) transaction support, 2) high concurrency environment, 3) high data consistency; conversely, the situation when choosing MyISAM includes: 1) mainly read operations, 2) no transaction support is required. InnoDB is suitable for applications that require high data consistency and transaction processing, such as e-commerce platforms, while MyISAM is suitable for read-intensive and transaction-free applications such as blog systems.

Explain the purpose of foreign keys in MySQL.Explain the purpose of foreign keys in MySQL.Apr 25, 2025 am 12:17 AM

In MySQL, the function of foreign keys is to establish the relationship between tables and ensure the consistency and integrity of the data. Foreign keys maintain the effectiveness of data through reference integrity checks and cascading operations. Pay attention to performance optimization and avoid common errors when using them.

What are the different types of indexes in MySQL?What are the different types of indexes in MySQL?Apr 25, 2025 am 12:12 AM

There are four main index types in MySQL: B-Tree index, hash index, full-text index and spatial index. 1.B-Tree index is suitable for range query, sorting and grouping, and is suitable for creation on the name column of the employees table. 2. Hash index is suitable for equivalent queries and is suitable for creation on the id column of the hash_table table of the MEMORY storage engine. 3. Full text index is used for text search, suitable for creation on the content column of the articles table. 4. Spatial index is used for geospatial query, suitable for creation on geom columns of locations table.

How do you create an index in MySQL?How do you create an index in MySQL?Apr 25, 2025 am 12:06 AM

TocreateanindexinMySQL,usetheCREATEINDEXstatement.1)Forasinglecolumn,use"CREATEINDEXidx_lastnameONemployees(lastname);"2)Foracompositeindex,use"CREATEINDEXidx_nameONemployees(lastname,firstname);"3)Forauniqueindex,use"CREATEU

How does MySQL differ from SQLite?How does MySQL differ from SQLite?Apr 24, 2025 am 12:12 AM

The main difference between MySQL and SQLite is the design concept and usage scenarios: 1. MySQL is suitable for large applications and enterprise-level solutions, supporting high performance and high concurrency; 2. SQLite is suitable for mobile applications and desktop software, lightweight and easy to embed.

What are indexes in MySQL, and how do they improve performance?What are indexes in MySQL, and how do they improve performance?Apr 24, 2025 am 12:09 AM

Indexes in MySQL are an ordered structure of one or more columns in a database table, used to speed up data retrieval. 1) Indexes improve query speed by reducing the amount of scanned data. 2) B-Tree index uses a balanced tree structure, which is suitable for range query and sorting. 3) Use CREATEINDEX statements to create indexes, such as CREATEINDEXidx_customer_idONorders(customer_id). 4) Composite indexes can optimize multi-column queries, such as CREATEINDEXidx_customer_orderONorders(customer_id,order_date). 5) Use EXPLAIN to analyze query plans and avoid

Explain how to use transactions in MySQL to ensure data consistency.Explain how to use transactions in MySQL to ensure data consistency.Apr 24, 2025 am 12:09 AM

Using transactions in MySQL ensures data consistency. 1) Start the transaction through STARTTRANSACTION, and then execute SQL operations and submit it with COMMIT or ROLLBACK. 2) Use SAVEPOINT to set a save point to allow partial rollback. 3) Performance optimization suggestions include shortening transaction time, avoiding large-scale queries and using isolation levels reasonably.

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

SecLists

SecLists

SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.

PhpStorm Mac version

PhpStorm Mac version

The latest (2018.2.1) professional PHP integrated development tool

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

MantisBT

MantisBT

Mantis is an easy-to-deploy web-based defect tracking tool designed to aid in product defect tracking. It requires PHP, MySQL and a web server. Check out our demo and hosting services.

Atom editor mac version download

Atom editor mac version download

The most popular open source editor