You can watch the replay for this IDERA Live webcast, Leverage the Query Store for Better SQL Server Performance, on the IDERA Resource Center, http://ow.ly/bHys50A4rH8. SQL Server’s Query Store, since its introduction with SQL Server 2016, is becoming better utilized by database administrators to review the history and performance of SQL queries. The Query Store collects useful information for SQL queries such as run time statistics and execution plans for analysis and reporting. Join this session with Bullett Manale to learn more about how the Query Store works, how to configure it, and how IDERA’s SQL Diagnostic Manager can leverage the Query Store to improve the performance of SQL queries. Speaker: Bullett Manale is IDERA’s Director of Sales Engineering, has been working in technology for over 25 years. Starting as a tech support technician for Iomega supporting their backup software, he has since been a technical trainer and consultant for Deloitte, a sales engineer at Centerbeam, and a project manager at Shell Oil Company.

1. © 2019 IDERA, Inc. All rights reserved.
LEVERAGE THE QUERY STORE FOR BETTER
SQL SERVER PERFORMANCE
Presenter: Bullett Manale
VP of Sales Engineering

2. © 2019 IDERA, Inc. All rights reserved.
AGENDA
▪ Introduction to the Microsoft Query Store
▪ Getting Started and Best Practices
▪ Architecture
▪ Configuration and Options
▪ Enabling
▪ Query Store in the Cloud
▪ Configuring Query Store Using SQL Query Optimizer
▪ Reports
▪ Use Case Scenarios
▪ Leveraging SQL Query Store with SQL Diagnostic Manager
▪ Demonstration – SQL Diagnostic Manager
▪ Demonstration – DM Insights Available from the Azure Marketplace (Azure Data
Studio)
▪ Best Practices
▪ Troubleshooting
▪ Q&A

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MICROSOFT SQL QUERY STORE
The Query Store, a feature
introduced with SQL
Server 2016, provides the
ability to collect and
historically review
information related to
execution plans, queries
and runtime statistics
associated to SQL Server
transactions.
The query store is often
referred to as the flight
data recorder for SQL
Server

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GETTING STARTED WITH QUERY STORE
▪ Works on all Editions of SQL Server (2016, 2017)
▪ Is Configured at the Database Level
▪ Can be enabled using T-SQL or SSMS (version16 or higher) or SQL Azure
Data Studio
▪ Collects plans for DML that include, SELECT, INSERT, UPDATE,
DELETE, MERGE, and BULK INSERT.
▪ Query Store Data is Maintained in the Associated User Database Query
Store is Enabled on
▪ Cannot be Enabled for Master and TempDB System Databases
▪ Cannot be Used on Read-Only Databases
▪ The minimum permissions for using the SQL Server Query Store is VIEW
DATABASE STATE (Doesn’t include Force Plan and other admin commands)
▪ Available in the Cloud (more to follow on this)

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HOW QUERY STORE WORKS
Runtime
Statistics
QUERY
STORE
Query Text
and Query
Plan
Memory
Written to
ASYNC
Queue
Immediately
Flushed to
ASYNC
Queue by
Default Every
15 Minutes
plan store contains persistent execution plan information
runtime stats store contains persistent execution statistics
wait stats store (2017) contains persistent wait statistics info
Query Store Schema
ASYNC
WRITER
Immediately Sent to Queue
Delay Based on Flush Rate

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QUERY STORE CATALOG VIEWS
sys.database_query_store_options
sys.query_context_settings
sys.query_store_plan
sys.query_store_query
sys.query_store_query_text
sys.query_store_wait_stats (2017)
sys.query_store_runtime_stats
sys.query_store_runtime_stats_interval
https://docs.microsoft.com/en-us/sql/relational-databases/system-catalog-views/query-store-catalog-views-transact-sql?view=sql-server-2017

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QUERY STORE STORED PROCEDURES
sp_query_store_consistency_check – Consistency Check, run when QS
is in Error State
sp_query_store_flush_db – Used to flush in-memory data to disk
sp_query_store_force_plan – Used to set a plan to forced
sp_query_store_remove_plan – Removes plan from query store
sp_query_store_remove_query – Removes query and associated plans &
runtime stats
sp_query_store_reset_exec_stats – Clear runtime stats for specific query
plan
sp_query_store_unforce_plan – Removes a plan from being forced
https://docs.microsoft.com/en-us/sql/relational-databases/system-stored-procedures/query-store-stored-procedures-transact-sql?view=sql-server-
2017

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PRIMARY QUERY STORE SETTINGS
▪ Max Size - Default 100 MB, Azure DB Premium Edition 1GB, Azure Basic 10MB. Operation mode
switches to ‘Read’ when size is reached.
▪ Data Flush Interval (Minutes) – Default is 15. Begin on the default or higher setting initially, then
tune to lower value to mitigate performance data loss in the event of a failure. Other options include, 1,
5, 10, 15, 30 (minutes), 1 hour and 1 day.
▪ Query Store Capture Mode – Default is ALL. Determines the type of queries/plans that will be
captured and stored. AUTO will direct SQL Server to attempt to capture infrequent or ad-hoc queries.
▪ Size Based Cleanup Mode – Default is AUTO. When size of the query store reaches 90% of the
Max Size setting, queries will be chosen based on query execution time and likelihood of usefulness (ad-
hoc queries,etc). If set to OFF, data will not be groomed (unless based on stale queries) will ultimately
cause the Query Store State to change to READ.
▪ Stale Query Threshold (Days) – Default is 30. Retention period of the query store based on
persisted queries.
▪ Statistics Collection Interval – Default is 1 HOUR. Determines the frequency of aggregation of data.
This determines how

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ENABLING QUERY STORE
In SQL Management Studio, enable Query Store by
right clicking the database, select properties; then
Click on the Query Store properties page and set
operation mode to Read Write
OR
In T-SQL:
ALTER DATABASE <DATABASE NAME> SET
QUERY_STORE = ON; /* Set to OFF to Disable */
Requires at least version 16 of Management Studio or Current Version of
Azure Data Studio to Enable in the GUI
• SQL Server 2016 & 2017: Query Store is Disabled by
Default
• Cloud Implementations: Enabled and Set to
Read/Write by Default

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ENABLING THE QUERY STORE

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USING QUERY STORE IN THE CLOUD
▪ Query Store is a Supported Feature on Both Azure DB and Amazon RDS
▪ Consumption Over Time and Identify Costly Performance Problems.
▪ Some settings are not configurable compared to on premise and
functionality may vary based on the service offering (Premium vs Basic).
▪ For AzureDB, use Query Performance Insight to analyze DTU
▪ Azure Data Studio does not currently support the same feature set within
the client compared to SQL Server Management Studio 18

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SQL 2017 QUERY WAIT CATEGORIES
▪ Traditional wait types are now mapped to a category rather than
referencing the specific wait type.
▪ For example, instead of seeing ‘CX_Packet’ waits, you will now see
‘Parallelism’ as the Category.
▪ Arguably better than using the wait type (less confusing).
▪ Troubleshooting the category should be similar regardless of the
specific wait type.

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WAIT TYPES MAPPED TO CATEGORY TYPES IN SQL 2017
WAIT CATEGORY WAIT TYPES INCLUDED WITHIN CATEGORY
CPU SOS_SCHEDULER_YIELD
Worker Thread THREADPOOL
Lock LCK_M_%
Latch LATCH_%
Buffer Latch PAGELATCH_%
Buffer IO PAGEIOLATCH_%
Compilation* RESOURCE_SEMAPHORE_QUERY_COMPILE
SQL CLR CLR%, SQLCLR%
Mirroring DBMIRROR%
Transaction XACT%, DTC%, TRAN_MARKLATCH_%, MSQL_XACT_%, TRANSACTION_MUTEX
Idle SLEEP_%, LAZYWRITER_SLEEP, SQLTRACE_BUFFER_FLUSH, SQLTRACE_INCREMENTAL_FLUSH_SLEEP, SQLTRACE_WAIT_ENTRIES,
FT_IFTS_SCHEDULER_IDLE_WAIT, XE_DISPATCHER_WAIT, REQUEST_FOR_DEADLOCK_SEARCH, LOGMGR_QUEUE, ONDEMAND_TASK_QUEUE,
CHECKPOINT_QUEUE, XE_TIMER_EVENT
Preemptive PREEMPTIVE_%
Service Broker BROKER_% (but not BROKER_RECEIVE_WAITFOR)
Tran Log IO LOGMGR, LOGBUFFER, LOGMGR_RESERVE_APPEND, LOGMGR_FLUSH, LOGMGR_PMM_LOG, CHKPT, WRITELOG
Network IO ASYNC_NETWORK_IO, NET_WAITFOR_PACKET, PROXY_NETWORK_IO, EXTERNAL_SCRIPT_NETWORK_IOF
Parallelism CXPACKET, EXCHANGE
Memory RESOURCE_SEMAPHORE, CMEMTHREAD, CMEMPARTITIONED, EE_PMOLOCK, MEMORY_ALLOCATION_EXT,
RESERVED_MEMORY_ALLOCATION_EXT, MEMORY_GRANT_UPDATE
User Wait WAITFOR, WAIT_FOR_RESULTS, BROKER_RECEIVE_WAITFOR
Tracing TRACEWRITE, SQLTRACE_LOCK, SQLTRACE_FILE_BUFFER, SQLTRACE_FILE_WRITE_IO_COMPLETION,
SQLTRACE_FILE_READ_IO_COMPLETION, SQLTRACE_PENDING_BUFFER_WRITERS, SQLTRACE_SHUTDOWN, QUERY_TRACEOUT,
TRACE_EVTNOTIFF
Full Text Search FT_RESTART_CRAWL, FULLTEXT GATHERER, MSSEARCH, FT_METADATA_MUTEX, FT_IFTSHC_MUTEX, FT_IFTSISM_MUTEX, FT_IFTS_RWLOCK,
FT_COMPROWSET_RWLOCK, FT_MASTER_MERGE, FT_PROPERTYLIST_CACHE, FT_MASTER_MERGE_COORDINATOR,
PWAIT_RESOURCE_SEMAPHORE_FT_PARALLEL_QUERY_SYNC
Other Disk IO ASYNC_IO_COMPLETION, IO_COMPLETION, BACKUPIO, WRITE_COMPLETION, IO_QUEUE_LIMIT, IO_RETRY
Replication SE_REPL_%, REPL_%, HADR_% (but not HADR_THROTTLE_LOG_RATE_GOVERNOR), PWAIT_HADR_%, REPLICA_WRITES, FCB_REPLICA_WRITE,
FCB_REPLICA_READ, PWAIT_HADRSIM
Log Rate Governor LOG_RATE_GOVERNOR, POOL_LOG_RATE_GOVERNOR, HADR_THROTTLE_LOG_RATE_GOVERNOR, INSTANCE_LOG_RATE_GOVERNOR
https://docs.microsoft.com/en-us/sql/relational-databases/system-catalog-views/sys-query-store-wait-stats-transact-sql?view=sql-server-
2017

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BUILT IN REPORTS WITHIN THE SQL
QUERY STORE
▪ Regressed Queries
▪ Overall Resource Consumption
▪ Top Resource Consuming Queries
▪ Queries With Forced Plans
▪ Queries With High Variation
▪ Query Wait Statistics (2017 & Azure Only)
▪ Tracked Queries

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USE CASE / SCENARIOS
▪ Finding the most expensive queries for CPU, I/O, and memory
▪ Getting full history of query executions and plans
▪ Getting information about query regressions, finding performance
regressions and fixing them by forcing the previous query plan whose
performance is better than a newly generated plan
▪ Ideal for A/B Testing
▪ Excellent tool for evaluating performance after upgrading

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USE CASE SCENARIOS
▪ Pinpoint and fix queries with plan choice regressions
▪ Identify and tune top resource consuming queries
▪ A/B testing
▪ Keep performance stability during the upgrade to newer SQL Server

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QUERY STORE RECOMMENDED SETTINGS FOR
IDERA’S SQL DIAGNOSTIC MANAGER
ALTER DATABASE <database name>
SET QUERY_STORE = ON (
OPERATION_MODE = READ_WRITE, -- this is default
DATA_FLUSH_INTERVAL_SECONDS = 360, CLEANUP_POLICY =
(STALE_QUERY_THRESHOLD_DAYS = 30), -- this is default
MAX_STORAGE_SIZE_MB = 1024, -- 1 GB
INTERVAL_LENGTH_MINUTES = 15, -- defines aggregation
granularity, lower means more granular (default = 60)
SIZE_BASED_CLEANUP_MODE = AUTO, -- this is default, counter
balances size based cleanup (Cleanup Policy)
QUERY_CAPTURE_MODE = AUTO, -- helps to avoid collecting
infrequent or Ad Hoc based queries, Query Store will triage this for you
MAX_PLANS_PER_QUERY = 1000, -- default is 100, depends on
environment
WAIT_STATS_CAPTURE_MODE = ON -- default setting
);

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BEST PRACTICES

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BEST PRACTICES
▪ Monitor the Query Store State to make sure the query store has not reverted to
read only mode.
▪ Monitor the rate of growth more closely upon initialization and as you get closer
to the end of the retention period.
▪ Make sure to remember to watch forced plans and their performance, don’t
forget about them!
▪ You can use the new performance counter objects available to capture
performance metrics related to the query store
▪ Always try to minimize unnecessary collection of the query store data taking all
factors into account.

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TROUBLESHOOTING
▪ 1 - database is in read-only mode
2 - database is in single-user mode
4 - database is in emergency mode
8 - database is secondary replica (applies to Always On and Azure SQL Database geo-replication).
This value can be effectively observed only on readable secondary replicas
65536 - the Query Store has reached the size limit set by the MAX_STORAGE_SIZE_MB option.
131072 - The number of different statements in Query Store has reached the internal memory limit.
Consider removing queries that you do not need or upgrading to a higher service tier to enable
transferring Query Store to read-write mode.
Applies to: Azure SQL Database.
262144 - Size of in-memory items waiting to be persisted on disk has reached the internal memory
limit. Query Store will be in read-only mode temporarily until the in-memory items are persisted on
disk.
Applies to: Azure SQL Database.
524288 - Database has reached disk size limit. Query Store is part of user database, so if there is
no more available space for a database, that means that Query Store cannot grow further
anymore.
Applies to: Azure SQL Database.

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https://docs.microsoft.com/en-us/sql/relational-databases/performance/monitoring-performance-by-using-the-query-store?view=sql-server-
2017
APPENDIX: MICROSOFT EXAMPLES OF
TROUBLESHOOTING NEW WAIT CATEGORIES

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APPENDIX B: CONFIGURING QUERY STORE
▪ ALTER DATABASE <database name> SET QUERY_STORE (
OPERATION_MODE = READ_WRITE, CLEANUP_POLICY =
(STALE_QUERY_THRESHOLD_DAYS = 30),
DATA_FLUSH_INTERVAL_SECONDS = 3000,
MAX_STORAGE_SIZE_MB = 500, INTERVAL_LENGTH_MINUTES = 15,
SIZE_BASED_CLEANUP_MODE = AUTO, QUERY_CAPTURE_MODE =
AUTO, MAX_PLANS_PER_QUERY = 1000,
WAIT_STATS_CAPTURE_MODE = ON );

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THANKS!
Any questions?
You can find me at:
bullett.manale@idera.com