Shadow set of disks save as a backup in the event of disk failure. In most Operating System if any disk failure occurs it automatically switchover to place of failed disk. Improved
They allow the database to maintain read consistency between multiple transactions.
Latest Answer: 1.Transaction Rollback-When a transaction is rolled back to restore the old image.2.Transaction recovery-To undo any uncommitted changes when DB is open after instance failure.3.Read consistency-While transaction is on progress other users in DB do not ...
It is the set of before image data blocks that contain rows that are modified by a transaction.Each Rollback Segment entry
Latest Answer: A rollback segment entry consists of image of pre-update value, block address, data file number, transaction ID and transaction status (active or committed). A single rollback segment may contain several rollback entries and several active transactions. ...
It is a measure of well the data cache buffer is handling requests for data. Hit Ratio = (Logical Reads - Physical Reads - Hits Misses)/ Logical Reads.
When Segment is dropped.When Shrink (RBS only)When truncated (TRUNCATE used with drop storage option)
We should depend on export/import utility for backup/recovery (fully reliable) The tar command cannot be used for physical file backup, instead we can
The space used transaction entries and a deleted record does not become free immediately after completion due to delayed cleanout. Trailing nulls and length bytes are not stored. Inserts
Latest Answer: Hi,Database buffers are used to store copy of data of data blocks that has been used recently.the set of database block buffers are called db buffer cache.redo log buffers are used to store temorary entries for redo that supose to written to redo logfiles.thanksAlok. ...
Latest Answer: Hi,Dictionary cache is memory arear in shared pool.dictionary cache are used to hold db blocks of recently used data dictionary tables.thanksAlok. ...
Latest Answer: Number of times processes repeatedly query the dictionary table is called recursive hints. It is due to the data dictionary cache is too small. By increasing the SHARED_POOL_SIZE parameter we can optimize the size of ...
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