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define null valuenull value null means something is unknown it does not mean null the digit 0 null is as well employed as attribute value for a
explain the isa relationshipanswer isa relationship - isa notation is employed in generalization specialization to depict relationship among lower
define functional and multivalued dependencies ans a functional dependency is a assets of the semantics of the attributes
describe five main functions of a database administratorans a database administrator dba is a person who is accountable for the environmental aspects
explain domain calculusdomain calculus is one of the types of the relational calculus the formal specification of the domain calculus was planned
explain the ansi sparc architecturethe three-schema architecture is as well known as ansi sparc architecture the aim of the three-schema architecture
explain two phase locking protocola transaction is consider as to follow the two-phase locking protocol if all locking operations precede the first
explain the dynamic hashing techniques there are two methods in it extendible hashing - stores an access structure in addition to the file and
explain hashing techniquesthe hashing techniques can be categorized as static hashing techniques - in this method the data can be viewed a collection
define the query optimisationthe query parser commonly generates a standard initial tree to correspond to an sql query with no doing any optimization
define deadlock recovery measures to recover from deadlock the cycle in the
what is the need of a log in a dbms briefly describe the various types of records that are normally present in a log
what are wait-for-graphsgive the algorithm to construct a wait-for-graph from a given schedule of transactions how can deadlocks be detected from
which sorting technique is used to sort databases whose sizes are very big give one such algorithm why do sorting techniques like quicksort
what are the two integrity rules ans the two integrity rules are entity integrity rule amp referential integrity rule entity integrity
what is the meaning of recovery in deferred update methods if a transaction fails before arriving its commit point it will not have altered the
define the immediate update the immediate update methods may apply changes to the database on disk before the transaction arrives a successful
explain the deferred update the deferred update methods do not physically update the database on disk till after a transaction reaches its commit
list the armstrongs axioms for functional dependencies what do you understand by soundness and completeness of these
list two restrictions that are applied on the modification updation insertion or deletion of base tables through view ans the two restrictions
define timestamp orderingans in timestamp-based method a serial order is made among the concurrent transaction by assigning to every transaction a
define the canonical coverans a canonical cover fc for f is a set of dependencies like f logically implies all dependencies in fc and fc logically
define direct file organizationthe direct file organization is employed to enhance the performance in accessing the records than sequential file
define the wait for graphans the wait-for-graph is a directed graph and consist of nodes and directed arcs the nodes of the graph are active
define check point and its impact on data base recovery ans there could be