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Define Hash files organization
a. Hashing includes computing the address of a data item by calculating a function on the search key value.
b. A hash function h is a function from the set of all search key values K to the set of all bucket addresses B.
We select a number of buckets to correspond to the number of search key values we will comprise stored in the database.
To carry out a lookup on a search key value Ki, we calculate hki, and search the bucket along with that address.
If two search keys i and j map to similar address, as h(Ki)=h(Kj), after that the bucket at the address acquired will consist of records with both search key values.
In this case we will have to verify the search key value of each record in the bucket to get the ones we want.
write-set(T): Each data items that are written by a transaction T
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An ideal data dictionary should have everything a DBA wants to know about the database. 1 Conceptual, External, and internal database descriptions. 2. Descriptions of attr
how to find entities
Hardware failure : Hardware failures are the failures when some disk or hardware chip fails. This may result in loss of data. One such trouble can be that a disk gets damaged and
Question: A DBMS built for Online Transaction Processing (OLTP) is generally regarded as unsuitable for data warehousing. Each system is designed with a different set of requir
Explain trivial dependency? Functional dependency of the form α ->β. is trivial if α C β. Trivial functional dependencies are satisfied by all the relations.
What is a super key? A super key is a set of one or more attributes that collectively permits us to recognize uniquely an entity in the entity set.
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Guidelines for creation of table: Table name should begin with an alphabet. In table name, single quotes and blank spaces are not allowed. Reserve words of that DBM
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