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Define Timestamp ordering
Ans In timestamp-based method, a serial order is made among the concurrent transaction by assigning to every transaction a unique nondecreasing number. The common value assigned to each transaction is the system clock value at the beginning of the transaction, therefore the name timestamp ordering. This value then can be employed in deciding the order in which the conflict between two transactions is resolved. A transaction along with a smaller timestamp value is considered to be an "older" transaction as compared to another transaction with a larger timestamp value.
Eliminate Columns Not Dependent On Key The Employee Relation satisfies - First normal form - As it has no repeating groups. Second normal form - As it do not have multi-a
the of super market system done in database
Explain the functions of data manager? Functions of Data Manager : - Convert operations in user's queries coming directly through query processor or indirectly in an applicatio
Explain the Cascadeless Schedule A cascadeless schedule is one in which for every pair of transactions Ti and Tj like that Tj reads a data item before written by Ti, the commit
Describe the Composite Key Composite Key: Sometimes one key is not enough to uniquely recognize a row. E.g. in a single class Roll is enough to search a student, but in the w
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Given the following set of functional dependencies {cf?bg, g?d, cdg?f, b?de, d?c} defined on R(b,c,d,e,f,g) a.Find a non-redundant cover. b.Find a canonical cover.
What are ways of finding out either an update is required or not for derived attributes? The ways to find out an update is required or, not are as: Explicit update
Example :; transfers transfer_amount from x's account to y's account ; Supposes x&y both accounts exist TRANSACTION (x, y, transfer_amount) Start transaction IF X AND Y
Question: (a) Discuss the difference between a composite key and a composite attribute. How would each be indicated in an E-R diagram? Support your answer with appropriate exam
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