Database Recovery Schemes Quiz

<p>ARIES Recovery Scheme</p> Signup and view all the answers

<p>Shadow paging</p> Signup and view all the answers

<p>Analysis, redo, undo</p> Signup and view all the answers

<p>Dirty pages and active transactions at the time of crash</p> Signup and view all the answers

<p>Fuzzy checkpointing</p> Signup and view all the answers

<p>Transaction table and dirty page table</p> Signup and view all the answers

<p>Logging data updates before the actual update is performed</p> Signup and view all the answers

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<p>Reverses effects of transactions that were active at the time of crash.</p> Signup and view all the answers

<p>Applies necessary changes to bring database to a consistent state.</p> Signup and view all the answers

<p>Both data updates and transaction commits</p> Signup and view all the answers

<p>Unique Log Sequence Number (LSN) and previous LSN of the transaction.</p> Signup and view all the answers

<p>Both begin_checkpoint and end_checkpoint records</p> Signup and view all the answers

<p>Storing data values before and after modification</p> Signup and view all the answers

<p>Transaction ID (TID), back pointer, next pointer, operation details</p> Signup and view all the answers

<p>Immediate update writes modified data item directly to disk</p> Signup and view all the answers

<p>Stores the modified version of a data item separately from the original</p> Signup and view all the answers

<p>Temporarily store data items to be modified</p> Signup and view all the answers

<p>Ensure recovery when in-place updates are used</p> Signup and view all the answers

<p>Suspended transaction execution, writing modified data to disk, logging checkpoint record, resuming transaction execution</p> Signup and view all the answers

<p>Redo or undo operations for transactions following the checkpoint record</p> Signup and view all the answers

<p>Steal, no-steal, force, or no-force methods</p> Signup and view all the answers

<p>Redoing a transaction in the commit table</p> Signup and view all the answers

<p>No undo and no redo</p> Signup and view all the answers

<p>Both an active table and a commit table</p> Signup and view all the answers

<p>They are redone</p> Signup and view all the answers

<p>Idempotent property</p> Signup and view all the answers

<p>Ignored</p> Signup and view all the answers

<p>It undoes all transactions during recovery</p> Signup and view all the answers

<p>Undo possible for some transactions, redo possible for others</p> Signup and view all the answers

<p>No undo and no redo for any transaction</p> Signup and view all the answers

<p>For all transactions in the active table</p> Signup and view all the answers

<p>They are flushed to disk before committing</p> Signup and view all the answers

<p>Helps with managing concurrency control</p> Signup and view all the answers

<p>To redo any changes that appear in the dirty page table</p> Signup and view all the answers

<p>Starts from the end of the log and proceeds backward while performing appropriate undo</p> Signup and view all the answers

<p>It allows transactions to commit only when all multiple nodes agree to commit individually</p> Signup and view all the answers

<p>To ensure that a transaction commits only when all multiple nodes agree to commit individually</p> Signup and view all the answers

<p>They are recovered under their own recovery protocol at each node</p> Signup and view all the answers

<p>The transaction is aborted if any one of these nodes fails or cannot commit</p> Signup and view all the answers

<p>Allows writing logs before changes are made to database pages</p> Signup and view all the answers

<p>No-Steal/Force property</p> Signup and view all the answers

<p>The purpose of the ARIES recovery scheme is to ensure that the database can be brought back to a consistent state after a failure, while preserving the ACID properties of transactions (Atomicity, Consistency, Isolation, Durability). It uses a combination of undo and redo operations, along with a write-ahead logging protocol, to achieve efficient and reliable recovery.</p> Signup and view all the answers

<p>The types of failures that may cause a database to become unavailable for use include transaction failure (due to incorrect input, deadlock, incorrect synchronization), system failure (due to addressing error, application error, operating system fault, RAM failure, etc.), and media failure (such as disk head crash, power disruption, etc).</p> Signup and view all the answers

<p>The purpose of a checkpointing process in the context of database recovery is to create a stable point in the transaction log and ensure that all modified data pages are written to disk. This allows the system to recover efficiently from a failure by reducing the amount of log records that need to be processed during the recovery phase.</p> Signup and view all the answers

<p>The purpose of data caching in the context of database recovery is to improve system performance by temporarily storing frequently accessed data in memory. However, during recovery, it is important to ensure that the cached data is consistent with the disk-based data to avoid data loss or inconsistency.</p> Signup and view all the answers

<p>The Write-Ahead Logging (WAL) protocol is used to ensure recovery when in-place updates are used, by writing the Before Image (BFIM) and After Image (AFIM) to the log.</p> Signup and view all the answers

<p>The database cache is used to temporarily store data items to be modified; the cache manager controls flushing using modified and pin-unpin bits.</p> Signup and view all the answers

<p>Transaction roll-back (undo) and roll-forward (redo) are used to maintain atomicity by restoring all Before Images (BFIM) or After Images (AFIM) to the database.</p> Signup and view all the answers

<p>Checkpointing involves suspended transaction execution, writing modified data to the disk, logging the checkpoint record, and resuming transaction execution.</p> Signup and view all the answers

<p>Immediate update method writes the modified data item directly to the disk, while deferred update method waits for the transaction to finish or a certain number of transactions to complete before writing the modified data item to the disk.</p> Signup and view all the answers

<p>The transaction log consists of records, each with a transaction ID (TID), back pointer to the previous log record, next pointer to the next log record, and operation details.</p> Signup and view all the answers

<p>Shadow update method stores the modified version of a data item separately from the original.</p> Signup and view all the answers

<p>The Redo phase in the ARIES Recovery Algorithm is required to reapply changes from log records to the database during recovery.</p> Signup and view all the answers

<p>The transaction log is a sequential file used for database recovery, storing data values before and after modification, as well as other relevant information.</p> Signup and view all the answers

<p>Write-Ahead Logging (WAL) protocol is used to ensure recovery when in-place updates are used, by writing the Before Image (BFIM) and After Image (AFIM) to the log.</p> Signup and view all the answers

<p>The database cache can be flushed to the disk using steal, no-steal, force, or no-force methods.</p> Signup and view all the answers

<p>During recovery, redo or undo operations are required for transactions following the checkpoint record to ensure consistent database state.</p> Signup and view all the answers

<p>The four different ways for handling recovery in database systems are: Steal/No-Force (Undo/Redo), Steal/Force (Undo/No-redo), No-Steal/No-Force (Redo/No-undo), and No-Steal/Force (Noundo/No-redo).</p> Signup and view all the answers

<p>The Deferred Update recovery scheme involves No Undo/Redo.</p> Signup and view all the answers

<p>In a single-user system, data update involves: 1) transactions recording updates in the log, 2) updates being saved on the database disk at commit point under the Write-Ahead Logging (WAL) scheme, 3) redoing all affected transactions using the log after a failure reboot, and 4) no undo being required due to no Anomalous Fatal Image (AFIM) being flushed to the disk before a transaction commits.</p> Signup and view all the answers

<p>In a concurrent users system, deferred update recovery requires both an active table and a commit table. During recovery, all transactions in the commit table are redone, while all transactions in the active table are ignored.</p> Signup and view all the answers

<p>The idempotent property of a redone transaction ensures its consistency in the commit table during recovery.</p> Signup and view all the answers

<p>The Undo/No-redo Algorithm involves flushing Anomalous Fatal Image (AFIMs) of a transaction to the database disk under Write-Ahead Logging (WAL) before it commits.</p> Signup and view all the answers

<p>In a single-user environment using the Undo/Redo Algorithm, the recovery manager undoes a transaction if it is in the active table and redoes a transaction if it is in the commit table.</p> Signup and view all the answers

<p>The recovery manager performs undo and redo for recovery in a concurrent execution environment using the Undo/Redo Algorithm.</p> Signup and view all the answers

<p>The Immediate Update recovery technique flushes Anomalous Fatal Image (AFIMs) to the database disk under Write-Ahead Logging (WAL) before a transaction commits, and the recovery manager undoes all transactions during recovery, with no redos.</p> Signup and view all the answers

<p>The active table and the commit table are used in deferred update recovery for concurrent users to ensure that all transactions in the commit table are redone, while all transactions in the active table are ignored during recovery.</p> Signup and view all the answers

<p>The No-Steal/Force (Noundo/No-redo) method of handling recovery means that no undo or redo is required for any transactions, as no Anomalous Fatal Image (AFIM) is flushed to the disk before a transaction commits.</p> Signup and view all the answers

<p>The purpose of the recovery manager in a database system is to ensure the consistency and integrity of the database after a failure or crash, by performing undo and redo operations as necessary.</p> Signup and view all the answers

<p>The ARIES recovery algorithm consists of two phases: the redo phase and the undo phase. The purpose of the redo phase is to reapply any changes that appear in the dirty page table, moving forward from the point in the log where all dirty pages have been flushed to the end of the log. The undo phase, on the other hand, starts from the end of the log and proceeds backward, performing appropriate undo operations and writing compensating records in the log for each undo.</p> Signup and view all the answers

<p>In a multidatabase system, the 'two-phase commit' (2PC) ensures that a transaction commits only when all multiple nodes agree to commit individually the part of the transaction they were executing. If any one of these nodes fails or cannot commit, then the transaction is aborted.</p> Signup and view all the answers

<p>The transaction log in database recovery records all the changes made to the database, allowing the system to redo committed transactions during the redo phase and undo uncommitted or aborted transactions during the undo phase. This helps maintain consistency by ensuring that all committed changes are applied and uncommitted changes are rolled back.</p> Signup and view all the answers

<p>The dirty page table in the ARIES recovery algorithm keeps track of the pages in the buffer pool that have been modified but not yet written to disk. It is significant because the redo phase of the algorithm reapply any changes that appear in the dirty page table to ensure that all committed changes are applied to the database.</p> Signup and view all the answers

<p>A multidatabase system is a special distributed database system where different nodes may run different types of database systems. Unlike a traditional distributed database system where all nodes run the same type of database system, a multidatabase system allows each node to run a different type of database system, such as relational or object-oriented.</p> Signup and view all the answers

<p>In a distributed fashion at multiple nodes, a transaction commits only when all these multiple nodes agree to commit individually the part of the transaction they were executing. If any one of these nodes fails or cannot commit the part of the transaction, then the transaction is aborted. Each node recovers the transaction under its own recovery protocol.</p> Signup and view all the answers

<p>The 'two-phase commit' (2PC) ensures that a transaction commits only when all multiple nodes agree to commit individually the part of the transaction they were executing in a distributed environment. If any one of these nodes fails or cannot commit, then the transaction is aborted.</p> Signup and view all the answers

<p>The dirty page table keeps track of modified pages in the buffer pool, while the transaction log records all changes made to the database. During recovery, the dirty page table helps identify changes that need to be redone, while the transaction log helps identify changes that need to be undone, ensuring that the database remains consistent.</p> Signup and view all the answers

<p>Checkpointing in the ARIES Recovery Algorithm serves the purpose of minimizing work for the recovery manager by committing transactions and keeping active transactions. This is achieved by writing begin_checkpoint and end_checkpoint records to the log, appending the transaction table and dirty page table to the log, and writing the LSN of the begin_checkpoint record to a special file.</p> Signup and view all the answers

<p>The ARIES recovery algorithm consists of three steps: analysis, redo, and undo. Analysis identifies dirty pages and transactions active at the time of crash, and determines the appropriate log record for redo to start. Redo applies necessary changes to bring the database to a consistent state. Undo reverses the effects of transactions that were active at the time of crash.</p> Signup and view all the answers

<p>In the ARIES Recovery Algorithm, Write Ahead Logging (WAL) ensures that log records are written for data updates, transaction commits, transaction aborts, undo, and transaction ends. Each log record has a unique Log Sequence Number (LSN) and stores the previous LSN of the transaction, transaction ID, and type of log record, which aids in efficient recovery.</p> Signup and view all the answers

<p>Fuzzy checkpointing in the ARIES Recovery Algorithm is used to reduce the cost of checkpointing and allow the system to continue executing transactions. It involves writing any necessary log records to the log during recovery, as the system continues to execute transactions, thus reducing the overall overhead of the checkpointing process.</p> Signup and view all the answers

<p>During checkpointing in the ARIES Recovery Algorithm, the transaction table and dirty page table are stored in the log, along with begin_checkpoint and end_checkpoint records, which are written to the log. Additionally, the LSN of the begin_checkpoint record is written to a special file for reference during recovery.</p> Signup and view all the answers

<p>The AFIM and BFIM in ARIES Recovery Algorithm maintain shadow copies of data items, providing a method to manage access to data items by concurrent transactions using both current and shadow directories. These shadow copies play a crucial role in the recovery process, aiding in ensuring database consistency and integrity during recovery operations.</p> Signup and view all the answers

<p>The Write Ahead Logging (WAL) protocol in the ARIES Recovery Algorithm ensures that log records are written before the corresponding data updates, transaction commits, transaction aborts, undo, and transaction ends are performed. This protocol helps maintain the integrity and consistency of the log, facilitating efficient recovery and ensuring durability of transactions.</p> Signup and view all the answers

<p>During the analysis phase of the ARIES recovery algorithm, the system identifies dirty pages and transactions active at the time of crash. It also determines the appropriate log record for redo to start by analyzing the state of the database and the log, in order to bring the database to a consistent state during recovery.</p> Signup and view all the answers

<p>Shadow paging is a method used in ARIES Recovery Algorithm to manage access to data items by concurrent transactions, using both current and shadow directories. It serves the purpose of maintaining data item consistency and integrity during concurrent access, and involves managing access to data items by maintaining both current and shadow directories, ensuring recoverability and consistency in the event of failures or crashes.</p> Signup and view all the answers

<p>In the log records of ARIES Recovery Algorithm, each record has a unique Log Sequence Number (LSN) and stores the previous LSN of the transaction, transaction ID, and type of log record. These components play a crucial role in efficient recovery, providing necessary information for identifying and managing transactions and their corresponding log records during the recovery process.</p> Signup and view all the answers

<p>The undo phase in the ARIES Recovery Algorithm reverses the effects of transactions that were active at the time of crash, ensuring consistency and integrity of the database. It plays a crucial role in rolling back the effects of incomplete or active transactions, and restoring the database to a consistent state during the recovery process.</p> Signup and view all the answers

<p>The 'Write Ahead Logging (WAL)' in the ARIES Recovery Algorithm ensures that log records are written before the corresponding data updates, transaction commits, transaction aborts, undo, and transaction ends are performed. This protocol helps maintain the integrity and consistency of the log, facilitating efficient recovery and ensuring durability of transactions.</p> Signup and view all the answers