Closing Oracle database or Instance for that matter means that the data stored in the database will not be available to the users. It is as simple to shutdown the database as it is to startup. You can use Oracle EM or good old SQL*PLUS to do this. SQL*PLUS is personally my favorite. (It was the first thing I liked about Oracle.) Well, talking about closing the database; the simple command to do so is the Shutdown. There are four different key words that you can use with this command; each has its own effect. These are Normal, Transactional, Immediate and Abort.
When the Shutdown command is used with Normal or no suffix then Oracle will wait for all users to disconnect, save all the unsaved data back to disks (Commit Transactions) and will perform a clean shutdown. The data will be in consistent state on next startup. This type of shutdown is extremely slow because you never know when a user will disconnect from the database. When the Shutdown command is used with Transactional suffix then Oracle will only wait for the current Transactions to complete, save the data to disks and will perform a clean shutdown. Data will be consistent at next startup. This type of shutdown is faster then Normal Shutdown but is still not ideal because you can’t tell for sure when a user will commit or rollback the transaction.
When the Shutdown command is issued with Immediate as suffix then Oracle will immediately close all connections to the database and will shutdown the database. However it will make sure that the data remains in consistent state. Means that it is also a clean shutdown. This is the ideal and most frequently used way to shutdown the database. Shutdown Abort is the brutal force. It will force all users to disconnect from the database loosing all the unsaved changes. You should never use this command to close the database except when it is absolutely necessary. On next startup Instance recovery will be needed to bring back the database in consistent state.
No comments:
Post a Comment