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WorksheetsOracle ch9
Total questions: 20
Worksheet time: 10mins
Which of the following statements is correct about indexes?
An index can be based on multiple columns of a table, but the columns must be of the same datatype.
An index can be based on multiple columns of a table, but the columns must be adjacent and specified in the order that they are defined in the table.
An index cannot have the same name as a table, unless the index and the table are in separate schemas.
None of the above statements is correct!
Which of these statements about indexes is incorrect?
Indexes can limit the amount of data that is returned in the results.
Indexes are mandatory objects for each column in a table.
Indexes can help keep results in memory and bring back results faster.
Without indexes, the entire table is scanned (full table scan) with each DML operation on the table.
Why do not place indexes on all tables and column combinations?
Because indexes are free.
Because they have no impact on performance and space.
Because indexes are mandatory.
Because indexes have impact on performance and space!
Which of the following statements is not a part of the structure of B-tree index?
Root, which contains entries that point to the next level.
Branch blocks, which in turn point to blocks at the next level.
A bitmap segment consisting of a string of bits.
The leaf blocks are doubly linked to facilitate the scanning of the index in an ascending as well as descending order of key values.
The leaf nodes, which contain the index entries that point to rows in the table.
An index is an optionally created database object used primarily to increase query performance.
True
False
Bitmap indexes should not be used if:
The cardinality (the number of distinct values) in the column is low.
The cardinality (the number of distinct values) in the column is high.
The number of rows in the table is high.
The column is used in Boolean algebra operations.
Multicolumn indexes are especially effective when you often use multiple columns in the WHERE clause when accessing a table?
True
False
What is the type of the index that is created by the following command: SQL> CREATE INDEX cust_idx1 ON cust(last_name);
Bitmap index
B-tree index
Partitioned index
Memory index.
For the same combination of columns; There can be only?
Only two visible indexes
Only one visible index
Only three visible indexes
Only four visible indexes
What will Oracle do when trying to rebuild the index online?
Oracle attempts to rollback on the table
Oracle attempts to commit on the table
Oracle attempts to acquire a lock on the table
Oracle attempts to unlock any lock on the table
Choose the correct statement after executing DROP VIEW statement to drop a view:
The related data will be deleted
The related base table will be dropped too
The view will be dropped alone
The related triggers will be dropped
Which of the following types of database objects can't have synonym?
Tables
views
Sequences
indexes
It is recommended that you separate tables and indexes into different tablespaces?
True
False
Which statements are true about Cycle Values of a sequence?
After an ascending sequence reaches its maximum value, you have to drop it.
After an ascending sequence reaches its maximum value, it generates its minimum value.
After a descending sequence reaches its minimum, it generates its maximum value.
After a descending sequence reaches its minimum, you have to drop it.
Which statement is false about Cache Options of a sequence?
Specifies how many values of the sequence pre-allocates and keeps in memory for faster access.
This integer value can have 28 or fewer digits.
The minimum value for this parameter is 20.
The minimum value for this parameter is 2
The following SQL statement is used to display the "INV_SEQ" sequence DDL statement: select dbms_metadata.get_ddl('SEQUENCE','INV_SEQ') from dual;
True
False
What are the two pseudo columns to access the sequence’s value?
Forwardval
Nextval
Retreivedval
Currval
Views are stored queries as well as other complex expressions and SQL constructs?
True
False
Choose the correct statements that describe the common uses of views:
Adding privileges to the user
Creation a User Account with password
Provide an interface layer between an application and physical tables.
Hide the complexity of an SQL query from an application.
Any user in the database has access to the public synonym?
True
False
