______________ rolls back all transactions that were incomplete at the time of crash

DBMS - RECOVERY SYSTEM MCQ

• The log is a sequence of ___________, recording all the update activities in the database
• In the ___________ scheme, a transaction that wants to update the database first creates a complete copy of the database
• The ____________ scheme uses a page table containing pointers to all pages; the page table itself and all updated pages are copied to a new location
• The current copy of the database is identified by a pointer, called _____________, which is stored on disk
• If a transaction does not modify the database until it has committed, it is said to use the ___________ technique
• If database modifications occur while the transaction is still active, the transaction is said to use the ___________technique
• ____________ using a log record sets the data item specified in the log record to the old value
• In the __________ phase, the system replays updates of all transactions by scanning the log forward from the last checkpoint
• The actions which are played in the order while recording it is called ______________ history
• A special redo-only log record is written to the log, where V1 is the value being restored to data item Xj during the rollback. These log records are sometimes called
• Which of the following is not a recovery technique?
• Checkpoints are a part of
• deals with soft errors, such as power failures
• Rollback of transactions is normally used to :
• A transaction performs on the isolation level of the Read Uncommitted if :
• Which commands are used to control which users have which privilege over which objects ?
• When a deadlock is detected the recovery is normally accomplished by :
• Which is not a desirable property of a transaction ?
• A directed graph which represents the deadlock is called :
• Transaction Throughput is :
• Data encryption techniques are particularly useful for
• Before any changes to database structure are attempted one should first:
• Which of the following modifications may not succeed?
• Because of the importance of making data model changes correctly, many professionals are ________ about using an automated process for database redesign
• Which of the following can cause a transaction failure
• If the transaction can no longer continue with its normal execution because of some internal condition, it is called as a _________
• If a system has entered and undesirable state due to which it is unable to continue with normal execution, it is called as _________
• If there is a hardware malfunction or a bug in the database that causes the loss of content of volatile storage, it is called as ________
• The assumption that the hardware errors bring the system to a halt is called as ________
• Which of the following is not a classification of storage
• If a failure has occurred in the midst of a transfer, it is called as _________
• State true or false: The destination block has incorrect information in case of a total failure
• The partitions of the database into fixed length storage units are called as __________
• The blocks residing on the disk are referred to as ___________
• The area of memory where blocks temporarily reside is called as ________
• The most widely used structure for recording database modification is called as _______
• An update log record describes a ________ database write
• Which of the following fields does the update log record have?
• The unique identifier of the transaction that performed the write operation is called as _______
• The value of the data item prior to the write is called as _________
• If a transaction does not modify the database until it has committed it is said to use a _______ modification technique
• We say that a transaction has been ________ when its commit log record has been output to stable storage
• State true or false: Using checkpoints reduces overhead
• A __________ checkpoint is a checkpoint where transactions are allowed to perform updates even while buffer blocks are being written out
• If the database modifications occur while the transaction is still active, the transaction is said to use the __________ modification technique
• The log is a sequence of _________ recording all the update activities in the database
• The current copy of the database is identified by a pointer, called ____________ which is stored on disk
• A special redo-only log record <Ti , Xj , V1> is written to the log, where V1 is the value being restored to data item Xj during the rollback. These log records are sometimes called
• In order to reduce the overhead in retrieving the records from the storage space we use
• The order of log records in the stable storage ____________ as the order in which they were written to the log buffer
• Before a block of data in main memory can be output to the database, all log records pertaining to data in that block must have been output to stable storage. This is
• Writing the buffered log to __________ is sometimes referred to as a log force
• The _______________ policy, allows a transaction to commit even if it has modified some blocks that have not yet been written back to disk
• ______________ policy allows multiple updates to accumulate on a block before it is output to stable storage, which can reduce the number of output operations greatly for frequently updated blocks
• The ___________ policy, allows the system to write modified blocks to disk even if the transactions thatmade those modifications have not all committed
• Locks on buffer blocks are unrelated to locks used for concurrency-control of transactions, and releasing them in a non-two-phase manner does not have any implications on transaction serializability. This is
• The __________________ contains a list of blocks that have been updated in the database buffer
• The operating system reserves space on disk for storing virtual-memory pages that are not currently in main memory; this space is called
• What was the name of the first commercially available microprocessor chip?
• The magnetic storage chip used to provide non-volatile direct access storage of data and that have no moving parts are known as
• Which of the following is used only for data entry and storage, and never for processing?
• Non-volatile storage needs to have a _________ where the loses in future can be recovered
• A dump of the database contents is also referred to as an _____________ dump
• ________ dump, writes out SQL DDL statements and SQL insert statements to a file, which can then be reexecuted to re-create the database
• _________ dump schemes have been developed that allow transactions to be active while the dump is in progress
• ARIES uses a ___________ to identify log records, and stores it in database pages
• ARIES supports ___________ operations, which are physical in that the affected page is physically identified, but can be logical within the page
• ______________ is used to minimize unnecessary redos during recovery
• __________ scheme that records only information about dirty pages and associated information and does not even require of writing dirty pages to disk
• Whenever an update operation occurs on a page, the operation stores the LSN of its log record in the _______ field of the page
• There are special redo-only log records generated during transaction rollback, called _________ in ARIES
• The __________________ contains a list of pages that have been updated in the database buffer
• ___________ determines which transactions to undo,which pages were dirty at the time of the crash, and the LSN from which the redo pass should start
• __________ starts from a position determined during analysis, and performs a redo, repeating history, to bring the database to a state it was in before the crash
• ______________ rolls back all transactions that were incomplete at the time of crash
• Which lock should be obtained to prevent a concurrent transaction from executing a conflicting read, insert or delete operation on the same key value
• The remote backup site is sometimes also called the
• Remote backup system must be _________ with the primary site
• The backup is taken by
• When the __________ the backup site takes over processing and becomes the primary
• The simplest way of transferring control is for the old primary to receive __________ from the old backup site
• The time to process the remote backup can be reduced by
• A _______________ configuration can make takeover by the backup site almost instantaneous
• A transaction commits as soon as its commit log record is written to stable storage at the primary site. This is
• A transaction commits as soon as its commit log record is written to stable storage at the primary and the backup site.This is
• If only the primary is active, the transaction is allowed to commit as soon as its commit log record is written to stable storage at the primary site. This is
• Once the lower-level lock is released, the operation cannot be undone by using the old values of updated data items, and must instead be undone by executing a compensating operation; such an operation is called
• Which of the following is used for undo operations alone ?
• Redo operations are performed exclusively using
• To perform logical redo or undo, the database state on disk must be operation ___________ that is, it should not have partial effects of any operation
• An operation is said to be __________ if executing it several times in a row gives the same result as executing it once
• Immediate database modification technique uses
• Shadow paging has
• For correct behavior during recovery, undo and redo operation must be
• If ___________ are not obtained in undo operation it will cause problem in undo-phase

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