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What this article shares with you is about how to understand SID and its usage. The editor thinks it is very practical, so I share it with you. I hope you can get something after reading this article.

Background of the question:

When installing the database, you find that there is an option for SID that needs to be provided. What exactly is this SID and what does it do?

What is SID?

REF: http://www.orafaq.com/wiki/ORACLE_SID

The Oracle System ID (SID) is used to uniquely identify a particular database on a system. For this reason, one cannot have more than one database with the same SID on a computer system.

When using RAC, all instances belonging to the same database must have unique SID's.

Oracle SID is used to uniquely identify a special database in the system, specifically a database instance (Oracle Instance). Because of this description, there will be no two database instances of the same SID on the same host. When using RAC, all instances belonging to the same database must have different SID.

How does SID identify a specified instance on a computer?

SID and Oracle_home hash together into a unique key value, which is used to point to a SGA. If either sid or oracle_home is not set correctly, it will not be correctly attached to the SGA.

If you want to switch between different Oracle instances, the user must set the corresponding SID environment variable. Use the following instructions under Unix

Export ORACLE_SID=orcl

View SID:

Select instance from v$thread

Master Note:Tom said that it is best not to modify the SID of the database.

Different from Service Name:

SID is defined to identify a unique database instance in the system, while Service Name is used to represent a service that can be provided by either one instance or multiple instances. ServiceName is used for the client to remotely connect to a database. It is defined in the client's tnsnames.ora file. ServiceName can be the same as SID or different. The server-side ServiceName is registered in Listener.

The above is how to understand SID and its usage. The editor believes that there are some knowledge points that we may see or use in our daily work. I hope you can learn more from this article. For more details, please follow the industry information channel.

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