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This quiz contains multiple-choice problems on index definition, bitmap, ordered indices and various hashing techniques.
In a __ clustering index, the index record contains the search-key value and a pointer to the first data record with that search-key value, and the rest of the records will be in the sequential pointers.
Continuous
Sparse
Straight
Dense
The goal of hashing is to produce a search that takes __ time.
O(1)
O(n^2)
O(log n)
O(n*log n)
A hash table can store a maximum of 10 records; currently, there are records in locations 1, 3, 4, 7, 8, 9, 10. The probability of a new record going into location 2, with hash functions resolving collisions by linear probing, is
0.1
0.6
0.2
0.5
Consider a hash table of size seven, with starting index zero and hash function (3x + 4)mod7. Assuming the hash table is initially empty, which of the following are the contents of the table when the sequence 1, 3, 8, 10 is inserted into the table using closed hashing (note that ‘_’ denotes an empty location in the table)?
8, _, _, _, _, _, 10
1, 8, 10, _, _, _, 3
1, _, _, _, _, _,3
1, 10, 8, _, _, _, 3
Before attempting any changes to database structure, one must first
Clearly understand the current structure and contents of the database only
Test any changes on a test database only
Create a complete backup of the operational database only
All of the above
How can you find rows that do not match some specified condition?
EXISTS
Double use of NOT EXISTS
NOT EXISTS
None of the above
Which of the following SQL statements are helpful in database redesign?
Correlated subqueries only
EXISTS/NOT EXISTS expressions only
Both of the above
None of the above
Which of the following SQL-92 standard SQL commands can be used to change a table name?
RENAME TABLE
CHANGE TABLE
ALTER TABLE
None of the above
If ‘h‘ is any hashing function and is used to hash ‘n‘ keys into a table of size ‘m‘, where n<=m, the expected number of collisions involving a particular key ‘x‘ is
Less than 1
Less than n
Less than m
Less than n/2
The __ index is created for larger index values if they exist.
Multi-level
Sequential
Pointed
Multiple
The searching technique that takes O(1) time to find particular data is
Linear search
Binary search
Hashing
Tree search
The process of reading a database schema and producing a data model from it is known as
Data modeling
Database design
Reverse engineering
None of the above
In ordered indices, if the file containing the records is sequentially ordered, a __’s search key also defines the sequential order of the file.
Non-clustered index
Structured index
Unstructured index
Clustered index
An __ consists of a search-key value and pointers to one or more records with that value as their search-key value.
Index hash
Index entry
Index cluster
Index map
The search key of __ indices specifies an order different from the sequential order of the file.
Non-clustered
Secondary
Both of the above
None of the above
