DP-300 : Administering Relational Databases on Microsoft Azure : Part 05

DP-300 : Administering Relational Databases on Microsoft Azure : Part 05

1. You have an Azure Synapse Analytics dedicated SQL pool named Pool1 and a database named DB1. DB1 contains a fact table named Table.

   You need to identify the extent of the data skew in Table1.

   What should you do in Synapse Studio?

   • Connect to Pool1 and query sys.dm_pdw_nodes_db_partition_stats.
   • Connect to the built-in pool and run DBCC CHECKALLOC.
   • Connect to Pool1 and run DBCC CHECKALLOC.
   • Connect to the built-in pool and query sys.dm_pdw_nodes_db_partition_stats.

   Explanation:
   Use sys.dm_pdw_nodes_db_partition_stats to analyze any skewness in the data.

2. You have an Azure Synapse Analytics dedicated SQL pool.

   You run PDW_SHOWSPACEUSED(‘dbo.FactInternetSales’); and get the results shown in the following table.

   

   Which statement accurately describes the dbo.FactInternetSales table?

   • The table contains less than 10,000 rows.
   • All distributions contain data.
   • The table uses round-robin distribution
   • The table is skewed.
   Explanation:

   The rows per distribution can vary up to 10% without a noticeable impact on performance. Here the distribution varies more than 10%. It is skewed.

   Note: SHOWSPACEUSED displays the number of rows, disk space reserved, and disk space used for a specific table, or for all tables in a Azure Synapse Analytics or Parallel Data Warehouse database.
   This is a very quick and simple way to see the number of table rows that are stored in each of the 60 distributions of your database. Remember that for the most balanced performance, the rows in your distributed table should be spread evenly across all the distributions.

   ROUND_ROBIN distributed tables should not be skewed. Data is distributed evenly across the nodes by design.

3. DRAG DROP

   You have an Azure SQL managed instance named SQLMI1 that has Resource Governor enabled and is used by two apps named App1 and App2.

   You need to configure SQLMI1 to limit the CPU and memory resources that can be allocated to App1.

   Which four actions should you perform in sequence? To answer, move the appropriate actions from the list of actions to the answer area and arrange them in the correct order.

   

   

4. 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 SQL Server 2019 on an Azure virtual machine.

   You are troubleshooting performance issues for a query in a SQL Server instance.

   To gather more information, you query sys.dm_exec_requests and discover that the wait type is PAGELATCH_UP and the wait_resource is 2:3:905856.

   You need to improve system performance.

   Solution: You shrink the transaction log file.

   Does this meet the goal?

   • Yes
   • No

5. 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 SQL Server 2019 on an Azure virtual machine.

   You are troubleshooting performance issues for a query in a SQL Server instance.

   To gather more information, you query sys.dm_exec_requests and discover that the wait type is PAGELATCH_UP and the wait_resource is 2:3:905856.

   You need to improve system performance.

   Solution: You change the data file for the master database to autogrow by 10 percent.

   Does this meet the goal?

   • Yes
   • No

6. 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 SQL Server 2019 on an Azure virtual machine.

   You are troubleshooting performance issues for a query in a SQL Server instance.

   To gather more information, you query sys.dm_exec_requests and discover that the wait type is PAGELATCH_UP and the wait_resource is 2:3:905856.

   You need to improve system performance.

   Solution: You reduce the use of table variables and temporary tables.

   Does this meet the goal?

   • Yes
   • No

7. You have an Azure SQL database named db1 on a server named server1.

   You need to modify the MAXDOP settings for db1.

   What should you do?

   • Connect to db1 and run the sp_configure command.
   • Connect to the master database of server1 and run the sp_configure command.
   • Configure the extended properties of db1.
   • Modify the database scoped configuration of db1.

8. 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 SQL Server 2019 on an Azure virtual machine.

   You are troubleshooting performance issues for a query in a SQL Server instance.

   To gather more information, you query sys.dm_exec_requests and discover that the wait type is PAGELATCH_UP and the wait_resource is 2:3:905856.

   You need to improve system performance.

   Solution: You create additional tempdb files.

   Does this meet the goal?

   • Yes
   • No

9. You have SQL Server on an Azure virtual machine.

   You need to add a 4-TB volume that meets the following requirements:

   – Maximizes IOPs
   – Uses premium solid state drives (SSDs)

   What should you do?

   • Attach two mirrored 4-TB SSDs.
   • Attach a stripe set that contains four 1-TB SSDs.
   • Attach a RAID-5 array that contains five 1-TB SSDs.
   • Attach a single 4-TB SSD.

10. You have an Azure SQL database named db1 on a server named server1.

    The Intelligent Insights diagnostics log identifies that several tables are missing indexes.

    You need to ensure that indexes are created for the tables.

    What should you do?

    • Run the DBCC SQLPERF command.
    • Run the DBCC DBREINDEX command.
    • Modify the automatic tuning settings for db1.
    • Modify the Query Store settings for db1.

11. You have an Azure SQL managed instance named SQL1 and two Azure web apps named App1 and App2.

    You need to limit the number of IOPs that App2 queries generate on SQL1.

    Which two actions should you perform on SQL1? Each correct answer presents part of the solution.

    NOTE: Each correct selection is worth one point.

    • Enable query optimizer fixes.
    • Enable Resource Governor.
    • Enable parameter sniffing.
    • Create a workload group.
    • Configure In-memory OLTP.
    • Run the Database Engine Tuning Advisor.
    • Reduce the Max Degree of Parallelism value.
12. This is a case study. Case studies are not timed separately. You can use as much exam time as you would like to complete each case. However, there may be additional case studies and sections on this exam. You must manage your time to ensure that you are able to complete all questions included on this exam in the time provided.

    To answer the questions included in a case study, you will need to reference information that is provided in the case study. Case studies might contain exhibits and other resources that provide more information about the scenario that is described in the case study. Each question is independent of the other questions in this case study.

    At the end of this case study, a review screen will appear. This screen allows you to review your answers and to make changes before you move to the next section of the exam. After you begin a new section, you cannot return to this section.

    To start the case study

    To display the first question in this case study, click the Next button. Use the buttons in the left pane to explore the content of the case study before you answer the questions. Clicking these buttons displays information such as business requirements, existing environment, and problem statements. If the case study has an All Information tab, note that the information displayed is identical to the information displayed on the subsequent tabs. When you are ready to answer a question, click the Question button to return to the question.

    Overview

    Litware, Inc. is a renewable energy company that has a main office in Boston. The main office hosts a sales department and the primary datacenter for the company.

    Physical Locations

    Litware has a manufacturing office and a research office is separate locations near Boston. Each office has its own datacenter and internet connection.

    Existing Environment

    Network Environment

    The manufacturing and research datacenters connect to the primary datacenter by using a VPN.

    The primary datacenter has an ExpressRoute connection that uses both Microsoft peering and private peering. The private peering connects to an Azure virtual network named HubVNet.

    Identity Environment

    Litware has a hybrid Azure Active Directory (Azure AD) deployment that uses a domain named litwareinc.com. All Azure subscriptions are associated to the litwareinc.com Azure AD tenant.

    Database Environment

    The sales department has the following database workload:

    – An on-premises named SERVER1 hosts an instance of Microsoft SQL Server 2012 and two 1-TB databases.
    – A logical server named SalesSrv01A contains a geo-replicated Azure SQL database named SalesSQLDb1. SalesSQLDb1 is in an elastic pool named SalesSQLDb1Pool. SalesSQLDb1 uses database firewall rules and contained database users.
    – An application named SalesSQLDb1App1 uses SalesSQLDb1.

    The manufacturing office contains two on-premises SQL Server 2016 servers named SERVER2 and SERVER3. The servers are nodes in the same Always On availability group. The availability group contains a database named ManufacturingSQLDb1

    Database administrators have two Azure virtual machines in HubVnet named VM1 and VM2 that run Windows Server 2019 and are used to manage all the Azure databases.

    Licensing Agreement

    Litware is a Microsoft Volume Licensing customer that has License Mobility through Software Assurance.

    Current Problems

    SalesSQLDb1 experiences performance issues that are likely due to out-of-date statistics and frequent blocking queries.

    Requirements

    Planned Changes

    Litware plans to implement the following changes:

    – Implement 30 new databases in Azure, which will be used by time-sensitive manufacturing apps that have varying usage patterns. Each database will be approximately 20 GB.
    – Create a new Azure SQL database named ResearchDB1 on a logical server named ResearchSrv01. ResearchDB1 will contain Personally Identifiable Information (PII) data.
    – Develop an app named ResearchApp1 that will be used by the research department to populate and access ResearchDB1.
    – Migrate ManufacturingSQLDb1 to the Azure virtual machine platform.
    – Migrate the SERVER1 databases to the Azure SQL Database platform.

    Technical Requirements

    Litware identifies the following technical requirements:

    – Maintenance tasks must be automated.
    – The 30 new databases must scale automatically.
    – The use of an on-premises infrastructure must be minimized.
    – Azure Hybrid Use Benefits must be leveraged for Azure SQL Database deployments.
    – All SQL Server and Azure SQL Database metrics related to CPU and storage usage and limits must be analyzed by using Azure built-in functionality.

    Security and Compliance Requirements

    Litware identifies the following security and compliance requirements:

    – Store encryption keys in Azure Key Vault.
    – Retain backups of the PII data for two months.
    – Encrypt the PII data at rest, in transit, and in use.
    – Use the principle of least privilege whenever possible.
    – Authenticate database users by using Active Directory credentials.
    – Protect Azure SQL Database instances by using database-level firewall rules.
    – Ensure that all databases hosted in Azure are accessible from VM1 and VM2 without relying on public endpoints.

    Business Requirements

    Litware identifies the following business requirements:

    – Meet an SLA of 99.99% availability for all Azure deployments.
    – Minimize downtime during the migration of the SERVER1 databases.
    – Use the Azure Hybrid Use Benefits when migrating workloads to Azure.
    – Once all requirements are met, minimize costs whenever possible.

    1. You need to identify the cause of the performance issues on SalesSQLDb1.

       Which two dynamic management views should you use? Each correct answer presents part of the solution.

       NOTE: Each correct selection is worth one point.

       • sys.dm_pdw_nodes_tran_locks

       • sys.dm_exec_compute_node_errors

       • sys.dm_exec_requests

       • sys.dm_cdc_errors

       • sys.dm_pdw_nodes_os_wait_stats

       • sys.dm_tran_locks

       Explanation:

       SalesSQLDb1 experiences performance issues that are likely due to out-of-date statistics and frequent blocking queries.

       A: Use sys.dm_pdw_nodes_tran_locks instead of sys.dm_tran_locks from Azure Synapse Analytics (SQL Data Warehouse) or Parallel Data Warehouse.

       E: Example:
       The following query will show blocking information.
       SELECT
       t1.resource_type,
       t1.resource_database_id,
       t1.resource_associated_entity_id,
       t1.request_mode,
       t1.request_session_id,
       t2.blocking_session_id
       FROM sys.dm_tran_locks as t1
       INNER JOIN sys.dm_os_waiting_tasks as t2
       ON t1.lock_owner_address = t2.resource_address;

       Note: Depending on the system you’re working with you can access these wait statistics from one of three locations:

       sys.dm_os_wait_stats: for SQL Server
       sys.dm_db_wait_stats: for Azure SQL Database
       sys.dm_pdw_nodes_os_wait_stats: for Azure SQL Data Warehouse

       Incorrect Answers:
       F: sys.dm_tran_locks returns information about currently active lock manager resources in SQL Server 2019 (15.x). Each row represents a currently active request to the lock manager for a lock that has been granted or is waiting to be granted.
       Instead use sys.dm_pdw_nodes_tran_locks.

13. HOTSPOT

    You have SQL Server on an Azure virtual machine.

    You review the query plan shown in the following exhibit.

    

    For each of the following statements, select yes if the statement is true. Otherwise, select no.

    NOTE: Each correct selection is worth one point.

    

    

14. A data engineer creates a table to store employee information for a new application. All employee names are in the US English alphabet. All addresses are locations in the United States. The data engineer uses the following statement to create the table.

    

    You need to recommend changes to the data types to reduce storage and improve performance.

    Which two actions should you recommend? Each correct answer presents part of the solution.

    NOTE: Each correct selection is worth one point.

    •  Change Salary to the money data type.
    • Change PhoneNumber to the float data type.
    • Change LastHireDate to the datetime2(7) data type.
    • Change PhoneNumber to the bigint data type.
    • Change LastHireDate to the date data type.

15. You have an Azure SQL database.

    You identify a long running query.

    You need to identify which operation in the query is causing the performance issue.

    What should you use to display the query execution plan in Microsoft SQL Server Management Studio (SSMS)?

    • Live Query Statistics
    • an estimated execution plan
    • an actual execution plan
    • Client Statistics
    Explanation:

    To include an execution plan for a query during execution
    1. On the SQL Server Management Studio toolbar, click Database Engine Query. You can also open an existing query and display the estimated execution plan by clicking the Open File toolbar button and locating the existing query.
    2. Enter the query for which you would like to display the actual execution plan.

    3. On the Query menu, click Include Actual Execution Plan or click the Include Actual Execution Plan toolbar button.

    

    Note: Actual execution plans are generated after the Transact-SQL queries or batches execute. Because of this, an actual execution plan contains runtime information, such as actual resource usage metrics and runtime warnings (if any). The execution plan that is generated displays the actual query execution plan that the SQL Server Database Engine used to execute the queries.

16. You have a version-8.0 Azure Database for MySQL database.

    You need to identify which database queries consume the most resources.

    Which tool should you use?

    • Query Store
    • Metrics
    • Query Performance Insight
    • Alerts
    Explanation:
    The Query Store feature in Azure Database for MySQL provides a way to track query performance over time. Query Store simplifies performance troubleshooting by helping you quickly find the longest running and most resource-intensive queries. Query Store automatically captures a history of queries and runtime statistics, and it retains them for your review. It separates data by time windows so that you can see database usage patterns. Data for all users, databases, and queries is stored in the mysql schema database in the Azure Database for MySQL instance.

17. You have SQL Server on an Azure virtual machine that contains a database named DB1.

    You have an application that queries DB1 to generate a sales report.

    You need to see the parameter values from the last time the query was executed.

    Which two actions should you perform? Each correct answer presents part of the solution.

    NOTE: Each correct selection is worth one point.

    • Enable Last_Query_Plan_Stats in the master database
    • Enable Lightweight_Query_Profiling in DB1
    • Enable Last_Query_Plan_Stats in DB1
    • Enable Lightweight_Query_Profiling in the master database
    • Enable PARAMETER_SNIFFING in DB1
    Explanation:

    Last_Query_Plan_Stats allows you to enable or disable collection of the last query plan statistics (equivalent to an actual execution plan) in sys.dm_exec_query_plan_stats.

    Lightweight profiling can be disabled at the database level using the LIGHTWEIGHT_QUERY_PROFILING database scoped configuration: ALTER DATABASE SCOPED CONFIGURATION SET LIGHTWEIGHT_QUERY_PROFILING = OFF;.

    Incorrect Answers:
    E: Parameter sensitivity, also known as “parameter sniffing”, refers to a process whereby SQL Server “sniffs” the current parameter values during compilation or recompilation, and passes it along to the Query Optimizer so that they can be used to generate potentially more efficient query execution plans.

    Parameter values are sniffed during compilation or recompilation for the following types of batches:
    – Stored procedures
    – Queries submitted via sp_executesql
    – Prepared queries

18. HOTSPOT

    You have SQL Server on an Azure virtual machine that contains a database named Db1.

    You need to enable automatic tuning for Db1.

    How should you complete the statements? To answer, select the appropriate answer in the answer area.

    NOTE: Each correct selection is worth one point.

    

    

    Explanation:

    Box 1: SET AUTOMATIC_TUNING = AUTO
    To enable automatic tuning on a single database via T-SQL, connect to the database and execute the following query:

    ALTER DATABASE current SET AUTOMATIC_TUNING = AUTO

    Setting automatic tuning to AUTO will apply Azure Defaults.

    Box 2: SET AUTOMATIC_TUNING (FORCE_LAST_GOOD_PLAN = ON)
    To configure individual automatic tuning options via T-SQL, connect to the database and execute the query such as this one:

    ALTER DATABASE current SET AUTOMATIC_TUNING (FORCE_LAST_GOOD_PLAN = ON)

    Setting the individual tuning option to ON will override any setting that database inherited and enable the tuning option. Setting it to OFF will also override any setting that database inherited and disable the tuning option.

19. You deploy a database to an Azure SQL Database managed instance.

    You need to prevent read queries from blocking queries that are trying to write to the database.

    Which database option should set?

    • PARAMETERIZATION to FORCED

    • PARAMETERIZATION to SIMPLE

    • Delayed Durability to Forced

    • READ_COMMITTED_SNAPSHOT to ON

    Explanation:

    In SQL Server, you can also minimize locking contention while protecting transactions from dirty reads of uncommitted data modifications using either:
    – The READ COMMITTED isolation level with the READ_COMMITTED_SNAPSHOT database option set to ON.
    – The SNAPSHOT isolation level.

    If READ_COMMITTED_SNAPSHOT is set to ON (the default on SQL Azure Database), the Database Engine uses row versioning to present each statement with a transactionally consistent snapshot of the data as it existed at the start of the statement. Locks are not used to protect the data from updates by other transactions.

    Incorrect Answers:
    A: When the PARAMETERIZATION database option is set to SIMPLE, the SQL Server query optimizer may choose to parameterize the queries. This means that any literal values that are contained in a query are substituted with parameters. This process is referred to as simple parameterization. When SIMPLE parameterization is in effect, you cannot control which queries are parameterized and which queries are not.

    B: You can specify that all queries in a database be parameterized by setting the PARAMETERIZATION database option to FORCED. This process is referred to as forced parameterization.

    C: Delayed transaction durability is accomplished using asynchronous log writes to disk. Transaction log records are kept in a buffer and written to disk when the buffer fills or a buffer flushing event takes place. Delayed transaction durability reduces both latency and contention within the system.

    Some of the cases in which you could benefit from using delayed transaction durability are:
    You can tolerate some data loss.
    You are experiencing a bottleneck on transaction log writes.
    Your workloads have a high contention rate.

20. You have an Azure SQL database.

    You discover that the plan cache is full of compiled plans that were used only once.

    You run the select * from sys.database_scoped_configurations Transact-SQL command and receive the results shown in the following table.

    

    You need relieve the memory pressure.

    What should you configure?

    • LEGACY_CARDINALITY_ESTIMATION

    • QUERY_OPTIMIZER_HOTFIXES

    • OPTIMIZE_FOR_AD_HOC_WORKLOADS

    • ACCELERATED_PLAN_FORCING

    Explanation:

    OPTIMIZE_FOR_AD_HOC_WORKLOADS = { ON | OFF }

    Enables or disables a compiled plan stub to be stored in cache when a batch is compiled for the first time. The default is OFF. Once the database scoped configuration OPTIMIZE_FOR_AD_HOC_WORKLOADS is enabled for a database, a compiled plan stub will be stored in cache when a batch is compiled for the first time. Plan stubs have a smaller memory footprint compared to the size of the full compiled plan.

    Incorrect Answers:
    A: LEGACY_CARDINALITY_ESTIMATION = { ON | OFF | PRIMARY }
    Enables you to set the query optimizer cardinality estimation model to the SQL Server 2012 and earlier version independent of the compatibility level of the database. The default is OFF, which sets the query optimizer cardinality estimation model based on the compatibility level of the database.

    B: QUERY_OPTIMIZER_HOTFIXES = { ON | OFF | PRIMARY }

    Enables or disables query optimization hotfixes regardless of the compatibility level of the database. The default is OFF, which disables query optimization hotfixes that were released after the highest available compatibility level was introduced for a specific version (post-RTM).