Oracle Database - System Identifier (SID)


The System Identifier (SID) identifies a specific database instance. The SID uniquely distinguishes the instance from any other instance on the same computer. Each database instance requires a unique SID and database name. In most cases, the SID is the same as the database name portion of the global database name.

A name that identifies a specific instance of a running pre-release 8.1 Oracle database. For any database, there is at least one instance referencing the database.

For pre-release 8.1 databases, SID is used to identify the database. The SID is included in the connect descriptor of a tnsnames.ora file and in the definition of the listener in the listener.ora file.

Each instance have an unique name :

SID or service name

If the destination service is:

  • an Oracle8i or later release database, then use Service Name
  • an Oracle release 8.0 database, then use the SID

How to

change it

To change the name of an existing database, you must use the CREATE CONTROLFILE statement to re-create your control files and specify a new database name.

See it

select * from V$SERVICES;

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