March 4, 2010 at 10:10 am
Hi,
I have been reading about read only mode /standby mode but i did not understood them.
Can someone explain please?
Thank you
March 4, 2010 at 11:55 am
Any database can be set to readonly mode. Readonly means that you can only read from the database.
Standby is typically used in a log-shipping or mirroring setup. The database that is in standby is a warm-spare.
Jason...AKA CirqueDeSQLeil
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March 4, 2010 at 3:46 pm
Read only mode is exactly what it suggests, the database can only be read, no updates are allowed. SQL does not use locking algorithms when a databases is readonly so there are performance advantages to setting a database read only if you know it is never going to be updated.
Standby mode is a restore option that leaves the database in a consistent, readable state but able to accept further restores if required. Log shipped standby databases are often in this state.
the database is readable when in standby mode because incomplete transactions are rolled back, but details of these 'undos' are kept in a 'standby file' (.tuf) so they can be undone when the next backup is restored. It is because there are roll backs to be undone and applied at the next restore that the database is read only, as to allow updates could lead to inconsistencies in the data.
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