Chapter 6 (Indexes, Synonyms,Sequences)

b. CREATE PUBLIC SYNONYM thetable FOR mytable;

Given the table created in Question 6, which of the following commands can Juan use to create a synonym that allows anyone to access the table without having to identify his schema in the table reference?

You use it to generate a series of integers . And you can generate unique primary keys for records

How can a sequence be used in a database?

1. If the numbers that are cached aren't used 2. stored in various tables 3. rollback occurs

How can gaps appear in values generated by a sequence?

Use the keywords "increment by" and use a negative number

How can you indicate that the values generated by a sequence should be in descending order?

B

If a column has low selectivity, this means: a. The column contains many distinct values. b. The column contains a small number of distinct values. c. A WHERE clause is always used in a query on the column. d. The selectivity of a column can't be determined.

Oracle 12c generates 20 integers automatically and stores them in memory.

If the CACHE or NOCACHE options aren't included in the CREATE SEQUENCE command, which of the following statements is correct?

g

Oracle 12c automatically creates an index for which type of constraints? a. NOT NULL b. PRIMARY KEY c. FOREIGN KEY d. UNIQUE KEY e. none of the above f. onlyaandb g. only b and d

When the table is small

Under what circumstances should you not create an index for a table?

C

What can be referenced to determine whether an index is used to perform a query? a. USER_INDEXES view b. query source code c. explain plan d. database access plan

index organized table and it might be useful when trying to conserve space being the the index and data are in one

What is an IOT and under what circumstances might it be useful?

Bitmap is better for duplicates and b trees is better for unique values

What is the difference between the B-tree and bitmap index structures?

if its uses a primary or unique constraint

When does Oracle 12c automatically create an index for a table?

When the table becomes large and retrieval speeds starts slowing down

When is an index appropriate for a table?

D

When is creating an index manually inappropriate? a. when queries return a large percentage of rows in the results b. when the table is small c. when the majority of table operations are updates d. all of the above e. onlyaandc

leaf blocks

Which node of the B-tree index contains ROWIDs?

C

Which of the following commands creates a private synonym? a. CREATE PRIVATE SYNONYM b. CREATE NONPUBLIC SYNONYM c. CREATE SYNONYM d. CREATE PUBLIC SYNONYM

a sequence

Which of the following generates a series of integers that can be stored in a database?

NEXTVAL

Which of the following generates an integer in a sequence? a. NEXTVAL b. CURVAL c. NEXT_VALUE d. CURR_VALUE e. NEXT_VAL f. CUR_VAL

C

Which of the following isn't a valid option for the CREATE SEQUENCE command? a. ORDER b. NOCYCLE c. MINIMUMVAL d. NOCACHE e. All of the above are valid options.

start with

Which of the following settings can't be modified with the ALTER SEQUENCE command?

c. DROP PUBLIC SYNONYM synonymname;

Which syntax is correct for removing a public synonym?

B

If a column has high selectivity or cardinality, which index type is most appropriate? a. IOT b. B-tree c. bitmap d. function-based index

the USER_INDEXS view

Which of the following can be used to determine whether an index exists?

alter index

Which of the following commands can you use to modify an index?