Online Access Free 070-762 Exam Questions

You are analyzing the performance of a database environment.
Applications that access the database are experiencing locks that are held for a large amount of time. You are experiencing isolation phenomena such as dirty, nonrepeatable and phantom reads.
You need to identify the impact of specific transaction isolation levels on the concurrency and consistency of data.
What are the consistency and concurrency implications of each transaction isolation level? To answer, drag the appropriate isolation levels to the correct locations. Each isolation level may be used once, more than once, or not at all. You may need to drag the split bar between panes or scroll to view content.

Correct Answer:

Explanation

Read Uncommitted (aka dirty read): A transaction T1executing under this isolation level can access data changed by concurrent transaction(s).
Pros:No read locks needed to read data (i.e. no reader/writer blocking). Note, T1 still takes transaction duration locks for any data modified.
Cons: Data is not guaranteed to be transactionally consistent.
Read Committed: A transaction T1 executing under this isolation level can only access committed data.
Pros: Good compromise between concurrency and consistency.
Cons: Locking and blocking. The data can change when accessed multiple times within the same transaction.
Repeatable Read: A transaction T1 executing under this isolation level can only access committed data with an additional guarantee that any data read cannot change (i.e. it is repeatable) for the duration of the transaction.
Pros: Higher data consistency.
Cons: Locking and blocking. The S locks are held for the duration of the transaction that can lower the concurrency. It does not protect against phantom rows.
Serializable: A transaction T1 executing under this isolation level provides the highest data consistency including elimination of phantoms but at the cost of reduced concurrency. It prevents phantoms by taking a range lock or table level lock if range lock can't be acquired (i.e. no index on the predicate column) for the duration of the transaction.
Pros: Full data consistency including phantom protection.
Cons: Locking and blocking. The S locks are held for the duration of the transaction that can lower the concurrency.
References:
https://blogs.msdn.microsoft.com/sqlcat/2011/02/20/concurrency-series-basics-of-transaction-isolation-levels/

Note: This question is part of a series of questions that present the same scenario. Each question in the series contains a unique solution. Determine whether the solution meets the stated goals.
You have a database that contains a table named Employees. The table stores information about the employees of your company.
You need to implement and enforce the following business rules:
- Limit the values that are accepted by the Salary column.
- Prevent salaries less than $15,000 and greater than $300,000 from being entered.
- Determine valid values by using logical expressions.
- Do not validate data integrity when running DELETE statements.
Solution: You implement a check constraint on the table.
Does the solution meet the goal?

• A.No
• B.Yes

Note: This question is part of a series of questions that present the same scenario. Each question in the series contains a unique solution that might meet the stated goals. Some question sets might have more than one correct solution, while others might not have a correct solution.
After you answer a question in this section, you will NOT be able to return to it. As a result, these questions will not appear in the review screen.
You have a database that is 130 GB and contains 500 million rows of data.
Granular transactions and mass batch data imports change the database frequently throughout the day.
Microsoft SQL Server Reporting Services (SSRS) uses the database to generate various reports by using several filters.
You discover that some reports time out before they complete.
You need to reduce the likelihood that the reports will time out.
Solution: You increase the number of log files for the database. You store the log files across multiple disks.
Does this meet the goal?

• A.No
• B.Yes

Note: This question is part of a series of questions that use the same answer choices. An answer choice may be correct for more than one question on the series. Each question is independent of the other questions in this series. Information and details provided in a question apply only to that question.
You work on an OLTP database that has no memory-optimized file group defined.
You have a table named tblTransaction that is persisted on disk and contains the information described in the following table:

Users report that the following query takes a long time to complete.

You need to create an index that:
-improves the query performance
-does not impact the existing index
-minimizes storage size of the table (inclusive of index pages).
What should you do?

• A.Create a clustered index on the table.
• B.Create a nonclustered index on the table.
• C.Create a hash index on the table.
• D.Create a nonclustered columnstore index on the table.
• E.Create a nonclustered filtered index on the table.
• F.Create a clustered columnstore index on the table.

You are maintaining statistics for a database table named tblTransaction. The table contains more than 10 million records.
You need to create a stored procedure that meets the following requirements:
- On weekdays, update statistics for a sample of the total number of records in the table.
- On weekends, update statistics by sampling all rows in the table.
A maintenance task will call this stored procedure daily.
How should you complete the stored procedure? To answer, select the appropriate Transact-SQL segments in the answer area.
NOTE: Each correct selection is worth one point.

Correct Answer:

Explanation

Box 1: UPDATE STATISTICS
Box 2: SAMPLE 20 PERCENT
UPDATE STATISTICS tablenameSAMPLE number { PERCENT | ROWS }
Specifies the approximate percentage or number of rows in the table or indexed view for the query optimizer to use when it updates statistics. For PERCENT, number can be from 0 through 100 and for ROWS, number can be from0 to the total number of rows.
Box 3: UPDATE STATISTICS
Box 4: WITH FULLSCAN
FULLSCAN computes statistics by scanning all rows in the table or indexed view. FULLSCAN and SAMPLE
100 PERCENT have the same results. FULLSCAN cannot be used with the SAMPLE option.
References: https://msdn.microsoft.com/en-us/library/ms187348.aspx