How to import oracle database How to export oracle database

Oracle database migration mainly relies on expdp and impdp tools. 1. expdp is used to export data. Its syntax is concise but has rich options. Pay attention to directory permissions and file size to avoid export failures. 2. impdp is used to import data. It is necessary to ensure that the target database space is sufficient, the character set is consistent and there are no objects with the same name. The remap_schema parameter can be used to resolve conflicts. 3. Parallel, query, network_link, exclude and other parameters can be used to optimize the migration process; 4. Large database migration requires attention to network environment, database resource utilization and batch migration strategies to improve efficiency and reduce risks. Only by mastering these steps and techniques can you

Oracle Database Data Migration: Import and Export

Many friends have asked me about importing and exporting Oracle databases. To put it bluntly, this thing is not that mysterious, but it is really a bit of skill to play with. Let’s talk about this article, not only telling you how to do it, but more importantly, telling you why you do it and the pitfalls you may have stepped on. After reading it, you can easily deal with various data migration challenges like me.

The cornerstone of Oracle data migration: Understanding expdp and impdp

Many old guys are still using exp and imp , but times have changed, friends. Now the mainstream is expdp and impdp . These two tools are the core of Oracle Data Pump. It has high efficiency and strong functions, and supports various fancy options. It is simply a data migration tool. They operate based on tablespaces rather than the entire database, which is particularly important in large database migrations. They can effectively control resource consumption and avoid business interruptions caused by long-term table locking.

expdp: a powerful tool for exporting data

The core of expdp is export, you can think of it as a powerful data packer. Its syntax is concise, but there are many options, which is what it charms.

 <code class="sql">expdp system/password@sid directory=dump_dir dumpfile=my_data.dmp schemas=schema1,schema2 tables=table1,table2</code> 

The meaning of this code is: use the system user to export table1 and table2 in schema1 and schema2 , the export file is named my_data.dmp , and it is stored in a directory named dump_dir . Remember, directory needs to be created in the database in advance.

There is a pitfall here: The permission setting of directory is very important. If you are not careful, the export will fail. Be sure to ensure that the exporter has read and write permissions to the directory. In addition, you should also pay attention to the size of the export file. Too large files may cause the export to fail or be extremely slow. You can consider exporting in batches or using parallel parameters to improve efficiency.

impdp: magic wand for importing data

impdp happens to be the reverse operation of expdp , which is responsible for importing the exported data files into the target database.

 <code class="sql">impdp system/password@sid directory=dump_dir dumpfile=my_data.dmp schemas=schema1,schema2</code> 

This code imports the data in my_data.dmp into schema1 and schema2 of the target database.

Another pitfall: the tablespace of the target database must have sufficient storage space, otherwise the import will fail. In addition, the character set of the target database and the character set of the source database must be consistent, otherwise garbled problems may occur. Moreover, you have to make sure that there is no object with the same name as the imported data in the target database, otherwise it will conflict. You can use the remap_schema parameter to solve this problem by mapping the source database's schema to another schema of the target database.

More advanced gameplay: The art of parameters

expdp and impdp provide a large number of parameters that allow you to precisely control the export and import process. For example:

• parallel : parallel export/import to improve efficiency.


• query : You can specify query conditions and export only data that meets the conditions.


• network_link : Export/import across databases.


• exclude : Exclude some objects.

Only by mastering these parameters can you truly control data migration.

Performance Optimization: My Experience

Performance optimization is crucial for migration of large databases. In addition to using parallel parameters, the following points can also be considered:

• Select the appropriate network environment: High-speed networks can significantly improve transmission speed.


• Get the most out of database resources: During the migration, minimize other database operations.


• Batch migration: break down large tasks into multiple small tasks to reduce risks.

Summary: You are not fighting alone

Import and export of Oracle databases is not easy, but as long as you master the usage of expdp and impdp and pay attention to some details, you can easily deal with various challenges. Remember, only by practicing more and summarizing more can you become a real database master. Don't forget that when you encounter problems, Google is your best friend.

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