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how does the system cope up with a record crash when recovery is going on after the first crashans in a system the undo and redo operations are
discuss deferred update technique of recovery what are the advantages ans the deferred update methods do not physically update the
what is system log what are the entries ans the system log that is generally written on stable storage contains the
describe the algorithm to draw the dependency graph ans algorithm to draw precedence graph is like thisa for every transaction ti
how does the two phase protocol ensure serializability in database schedules ans a transaction is termed to follow the two-phase locking
what is meant by heuristic optimisation discuss the main heuristics that are applied during query optimisation ans in heuristic
what is a query tree ans a query tree as well known as operator graph is a tree data structure that corresponds to a relational
what do you understand by transitive dependencies define with an example any two problems that can take place in the database if transitive
define multivalued dependency and 4nf ans multivalued dependency - assume r be a relation schema and let alpha sube r and beta sube r the
differentiate between b-tree and b tree ans a b-tree or balanced tree is a search tree along with additional constraints that makes
what are the advantages of having an index structure ans the index structures commonly provide secondary access paths which offer
define join and outer join and differentiate between them ans join - it generates all the combinations of tuples from two relations
define the basic operations of the relational algebra ans basic operators of relational algebra are1 union cup - selects tuples which
define partial key and primary key a partial key also known as discriminator is the set of attributes which can uniquely identify weak entities that
explain candidate key and super key a super key is a set of one or more than attributes that taken collectively permits us to identify uniquely a
explain derived and non-derived attributein few cases two or more attribute values are related for instance age and birthdate attributes of a person
define single value and multivalued attribute single value attribute comprise a single atomic value for an entity and multivalued attribute may have
determine the disadvantages of file based systemssome of the disadvantages of file based systems are like this data redundancy and inconsistency the
define query processingquery processing is the process of selecting the best plan or strategy to be employed in responding to a database request the
define the two phase locking protocol this is a protocol that is used to make sure serializability of transactions this protocol needs that every
define deadlock avoidance these protocols as well ensure that the system will never enter a deadlock state although the way it is done is different
define deadlock detection if a system does not employ a few protocols that make sure deadlock freedom after that a detection and recovery scheme
define deadlock prevention these protocols make sure that the system will never enter a deadlock state there are two methods to deadlock prevention
define two phase committwo phase commit to make sure atomicity all the sites where a transaction is being executed must agree on the final outcome of
define thomas write rulethomas write rule the thomas write rule is a modification of timestamp-ordering protocol for concurrency control assume that