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write short notes on transaction statea transaction may not always complete its implementation successfully such a transaction is termed aborteda
what is serializability explain its typesthe data base system must control concurrent implementation of transactions to ensure that the data base
describe log based recoverythe most usably structure for recording data base modification is the log the log is a sequence of log records recording
what is magnetic disksexplain itmagnetic disk provides the bulk of secondary storage of modern computer system the disk capacity is growing at over
explain hash file organizationhash functionsa the distribution is uniformhash functions assign each bucket the similar number of search -key values
write short notes on index structure of filesthere are two basic parts of indices1 ordered indices2 hash indicesevery technique must
define raid briefly explain ita range of disk organization methods collectively called redundant arrays of independent disks raido
describe file organisationa file is organized logically as a sequence of records these records are mapped onto disk blocksa fixed-length recordstype
explain mechanism of nested queriessql gives a mechanism for nesting subqueries a subquery is a select from where expression that is nested within
what is data definition language explain it in detailthe sql ddl allows specification of not only a set of relations but also information after each
what is aggregate function briefly describe itaggregate functions are functions that take a collection of values as input and return a one value sql
describe integrity and securitya domain constraintb referential integritya value that appears in one relation
what are data models explain it detailentity relationship model rectanglesellipsediamondslinesrelational model relational model use a collection of
describe relational modelstructure of relational data basebasic structuredatabase schemakeysschema diagramquery
explain about database system structurestorage manager authorization and integrity managertransaction managerfile managerbuffer managerstorage
define decision tree classifiersas the name suggests decision tree classifiers use a tree every leaf node has an associated class and every internal
what are the various forms of data transparencya fragmentation transparencyb replication transparencyc location transparency
what is vertical fragmentationvertical fragmentation divides the relation by decomposing the scheme r of relation
what is horizontal fragmentationhorizontal fragmentation divides the relation by assuming every tuple of r to one or more
what are the two approaches to store relations in distributed databasea replicationb
what is a heterogeneous distributed databasein a heterogeneous distributed database dissimilar sites may use different schemas and dissimilar dbms sw
what is a homogeneous distributed databasein homogeneous distributed databases all sites have the same database management system software are aware
write a query to define tables students and teachers as sub tables of peoplecreate table students of student under peoplecreate table teachers of
how to create values of structured typeconstructor functions are used to make values of structured types a function with the similar name as a
list some instances of collection typesa setsb arraysc