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How a Database Is Quiesced
The database administrator uses the ALTER SYSTEM QUIESCE RESTRICTED statement to quiesce the database. Only users SYS and SYSTEM can issue the ALTER SYSTEM QUIESCE RESTRICTED statement. For all instances with the database open, issuing this statement has the following effect:
Oracle instructs the Database Resource Manager in all instances to prevent all inactive sessions (other than SYS and SYSTEM) from becoming active. No user other than SYS and SYSTEM can start a new transaction, a new query, a new fetch, or a new PL/SQL operation.
Oracle waits for all existing transactions in all instances that were initiated by a user other than SYS or SYSTEM to finish (either commit or terminate). Oracle also waits for all running queries, fetches, and PL/SQL procedures in all instances that were initiated by users other than SYS or SYSTEM and that are not inside transactions to finish. If a query is carried out by multiple successive OCI fetches, Oracle does not wait for all fetches to finish. It waits for the current fetch to finish and then blocks the next fetch. Oracle also waits for all sessions (other than those of SYS or SYSTEM) that hold any shared resources (such as enqueues) to release those resources. After all these operations finish, Oracle places the database into quiesced state and finishes executing the QUIESCE RESTRICTED statement.
If an instance is running in shared server mode, Oracle instructs the Database Resource Manager to block logins (other than SYS or SYSTEM) on that instance. If an instance is running in non-shared-server mode, Oracle does not impose any restrictions on user logins in that instance.
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如何理解最后一句话：
If an instance is running in non-shared-server mode, Oracle does not impose any restrictions on user logins in that instance.
如果实例运行在非共享服务器模式（那也就是说是专用模式），此时数据库通过 ALTER SYSTEM QUIESCE RESTRICTED 变成了静默状态，那么对登录在实例上的用户不会产生任何影响？显然不对啊，莫非我对这句话的理解有问题？
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