write_item(T, X, old_value, new_value): This log entry records that transaction T changes the value of the database item X from old_value to new_value.read_item(T, X): This log entry records that transaction T reads the value of database item X.The log is kept on disk start_transaction(T): This log entry records that transaction T starts the execution.This information is needed to recover from transaction failure. The log keeps track of all transaction operations that affect the values of database items. It contains information about the start and end of each transaction and any updates which occur during the transaction. Recovery techniques are heavily dependent upon the existence of a special file known as a system log. So to prevent data loss recovery techniques based on deferred updates and immediate updates or backing up data can be used. The techniques used to recover lost data due to system crashes, transaction errors, viruses, catastrophic failure, incorrect command execution, etc. There are both automatic and non-automatic ways for both, backing up data and recovery from any failure situations. Overall, recovery techniques are essential to ensure data consistency and availability in Database Management System, and each technique has its own advantages and limitations that must be considered in the design of a recovery system. Software Engineering Interview Questions.Top 10 System Design Interview Questions and Answers.Top 20 Puzzles Commonly Asked During SDE Interviews. ![]() ![]() Commonly Asked Data Structure Interview Questions.Top 10 algorithms in Interview Questions.Top 20 Dynamic Programming Interview Questions.Top 20 Hashing Technique based Interview Questions.Top 50 Dynamic Programming (DP) Problems.Top 20 Greedy Algorithms Interview Questions.Top 100 DSA Interview Questions Topic-wise.
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