Exam 70-762 topic 1 question 48 discussion

Actual exam question from Microsoft's 70-762

Question #: 48
Topic #: 1

Note: This question is part of a series of questions that use the same or similar answer choices. An Answer choice may be correct for more than one question in the series. Each question independent of the other questions in this series. Information and details provided in a question apply only to that question.
You are a database developer for a company. The company has a server that has multiple physical disks. The disks are not part of a RAID array. The server hosts three Microsoft SQL Server instances. There are many SQL jobs that run during off-peak hours.
You must monitor and optimize the SQL Server to maximize throughput, response time, and overall SQL performance.
You need to identify previous situations where a modification has prevented queries from selecting data in tables.
What should you do?

A. Create a sys.dm_os_waiting_tasks query.
B. Create a sys.dm_exec_sessions query.
C. Create a Performance Monitor Data Collector Set.
D. Create a sys.dm_os_memory_objects query.
E. Create a sp_configure "˜max server memory' query.
F. Create a SQL Profiler trace.
G. Create a sys.dm_os_wait_stats query.
H. Create an Extended Event.

Show Suggested Answer

Suggested Answer: G 🗳️
sys.dm_os_wait_stats returns information about all the waits encountered by threads that executed. You can use this aggregated view to diagnose performance issues with SQL Server and also with specific queries and batches.

by Heisenberg008 at Feb. 24, 2020, 5:10 a.m.

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lukadataowner

5 years, 1 month ago

I think the correct answer is H. It is inconvenient to detect issues with sys.dm_os_wait_stats

upvoted 1 times

Jay2

4 years, 12 months ago

The question asks for previous situations. Extended Events will only measure new situations.

upvoted 4 times

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SzalonyZielonyRobak

5 years, 3 months ago

Yep - it is correct. It can show not only waits due to locks, but also CPU, DISK, Operating system etc. https://codingsight.com/main-usage-of-sys-dm_os_wait_stats/

upvoted 2 times

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Heisenberg008

5 years, 3 months ago

I can't delete my previous comment. G is correct.

upvoted 4 times

JohnFan

5 years, 3 months ago

sys.dm_os_wait_stats View information about completed waits at the instance level. Use this DMV to see how often processes are waiting while locks are taken. The sys.dm_os_wait_stats DMV is an aggregate view of all waits that occur when a requested resource is not available, a worker thread is idle typically due to background tasks, or an external event must complete first. There are many wait types unrelated to locks, so when using the sys.dm_os_wait_stats DMV, you should apply a filter to focus on lock waits only You can reset the cumulative values in the sys.dm_os_wait_stats DMV by executing the following statement: DBCC SQLPERF (N’sys.dm_os_wait_stats’, CLEAR);. Otherwise, these values are reset each time that the SQL Server service restarts. You use the sys.dm_os_wait_stats, sys.dm_exec_session_wait_stats, or sys.dm_os_waiting_tasks DMVs to gather information about the amount of time that threads must wait on resources, determine whether the server is experiencing CPU, memory, or IO pressure, or find out which resources are causing excessive waits.

upvoted 1 times

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