1.
Performance
troubleshooting
Azure SQL & SQL Server

2.
Jovan Popovic
Program manager Microsoft SQL Server/Azure
Azure/SQL/ASP.NET/Jquery
PhD Electrical Engineering
Sinergija, Tarabica,
PassSummit,
SqlBits, SqlKonferenz,
SqlSaturday,…

3.
Agenda
• Maintenance
• Monitoring usage
• Identify issues with wait
statistics
• Troubleshoot query plans
• Tools
• Blitz
• BPCHECK
• QPI
• ODS
• DbaTools

4.
Maintaining the instance
• Is your instance properly configured?
• TEMPDB, backups
• Are there any issues in databases?
• Tools
• First Responder Kit
• BPCHECK

5.
Sp_Blitz (First Responder Kit)
- sp_Blitz.sql
- https://www.brentozar.com/blitz/
EXEC [dbo].[sp_Blitz]
@CheckUserDatabaseObjects = 1 ,
@CheckProcedureCache = 0 ,
@OutputType = 'TABLE' ,
@OutputProcedureCache = 0 ,
@CheckProcedureCacheFilter = NULL,
@CheckServerInfo = 1

6.
Sp_blitz results
• Last good DBCC CHECKDB over 2 weeks old
• Many Plans for One Query
• 170 plans are present for a single query in the plan cache - meaning we
probably have parameterization issues.
• Cost threshold for parallelism
• Set to 5, its default value. Changing this sp_configure setting may reduce
CXPACKET waits.
• Max degree of parallelism
• Set to 0, its default value. Changing this sp_configure setting may reduce
CXPACKET waits.

7.
DBCC CHECKDB
• Options
• NOINDEX - Specifies that intensive checks of nonclustered indexes for user tables should not be performed. This decreases
the overall execution time. NOINDEX does not affect system tables because integrity checks are always performed on system
table indexes.
• PHYSICAL_ONLY - Limits the checking to the integrity of the physical structure of the page and record headers and the
allocation consistency of the database. This check is designed to provide a small overhead check of the physical consistency
of the database, but it can also detect torn pages, checksum failures, and common hardware failures that can compromise a
user's data.
• TABLOCK - Causes DBCC CHECKDB to obtain locks instead of using an internal database snapshot. This includes a short-term
exclusive (X) lock on the database. TABLOCK will cause DBCC CHECKDB to run faster on a database under heavy load, but
decreases the concurrency available on the database while DBCC CHECKDB is running.
• DATA_PURITY - Causes DBCC CHECKDB to check the database for column values that are not valid or out-of-range. For
example, DBCC CHECKDB detects columns with date and time values that are larger than or less than the acceptable range
for the datetime data type; or decimal or approximate-numeric data type columns with scale or precision values that are not
valid.
• Repair options
• REPAIR_ALLOW_DATA_LOSS - Tries to repair all reported errors. These repairs can cause some data loss.
• REPAIR_REBUILD - Performs repairs that have no possibility of data loss. This can include quick repairs, such as repairing
missing rows in non-clustered indexes, and more time-consuming repairs, such as rebuilding an index.

8.
SqlTiger Maintenance solution
• http://aka.ms/MaintenanceSolution
• Weekly DBCC CHECKDB on all online, read-write user databases below 1TB.
• Daily combination of DBCC CHECKALLOC, DBCC CHECKCATALOG, DBCC
CHECKTABLE (depending on VLDB setting) on all online, read-write user
databases over 1TB.
• Weekly execution of DBCC UPDATEUSAGE on all online, read-write
databases up to 4GB.
• Weekly execution of sp_createstats with indexonly.
• Weekly purge of all MSDB job history over 30d.
• Weekly purge of all maintenance plan text reports over 30d (if you are still
using package based maintenance plans).

9.
SqlTiger BPCHECK
• Check_BP_Servers.sql
EXEC usp_bpcheck @custompath, @dbScope, @allow_xpcmdshell,
@ptochecks, @duration, @logdetail, @diskfrag,
@ixfrag, @ixfragscanmode, @bpool_consumer,
@spn_check, @gen_scripts

10.
Bpcheck results

11.
Other tools
• sp_BlitzWho: What Queries are Running Now
• sp_BlitzCache: Most Resource-Intensive Queries
• sp_BlitzQueryStore: Most Resource-Intensive Queries in history
• sp_BlitzFirst: Real-Time Performance Advice
• More on
• https://github.com/microsoft/tigertoolbox
• https://github.com/BrentOzarULTD/SQL-Server-First-Responder-Kit

12.
PsDbaTools

13.
Index & Statistics Maintenance
• Create missing indexes
• Azure SQL Database automatic tuning
• SSMS, spBlitzIndex
• Rebuild/reorganize defragmented indexes
• Olla Hallengren, SqlTiger
• Drop duplicate indexes
• First Responder Kit
• Create statistics
• Update statistics
• Maintenance solution

14.
Index maintenance

15.
Index Maintenance
• Ola Hallengren Index Maintenance
• Sql Tiger Adaptive Index Defrag or Maintenance Solution
• Azure SQL Database AUTOMATIC_TUNING (CREATE_INDEX,
DROP_INDEX)
• sp_BlitzIndex

16.
Performance troubleshooting

17.
Why is my query running slow?
• Not enough CPU?
• Not enough memory?
• Too much IO?
• TempDB spill?
• Cardinality estimate?
• Wrong plan?
• Waiting some other query (blocked)?

18.
What to check?
• Is there CPU, memory, IO pressure?
• Why the plan is waiting? Is it blocked?
• Is the plan changed? Is it slower?

19.
SSMS reports

20.
SSMS Query Store

21.
Query processing
https://rusanu.com/2013/08/01/understanding-how-sql-server-executes-a-query/

22.
Thread lifecycle
Running
WaitSignal

23.
Demo

24.
Conclusion
• Identify root cause
• Ensure that server is fine
• Check resource usage
• Check query plan
• Check wait statistics & blockings