Some tips and tricks on performance optimization of SQL Server 2014. Presented at Hasin Tech Co., December 2015

1. Microsoft SQL Server
Monitoring and Profiling
Alireza Sadeghipour, Abouzar Noori
24th Azar 1394

2. Microsoft SQL Server:
Monitoring and Profiling
• Performance Monitoring
• Estimated Execution Plan
• Indexing
• Database Engine Tuning Advisor
• SQL Server Profiling

3. Before MS SQL
• Be aware of Select N+1 Problem when using EF lazy loading
• Log EF queries to find the problem:

4. Performance Monitoring

5. Resource Monitor
• First of all, check Resource Monitor and find sqlserver.exe

6. SQL Server Performance Counters

7. SQL Server Performance Counters
• Access Methods: Full Scans/sec
• Buffer Manager: Buffer Cache Hit Ratio
• Database: Transactions/sec
• Database: Write Transactions/sec
• General Statistics: User Connections

8. SQL Server Performance Counters (cont.)
• Locks: Lock Requests / Sec
• Locks: Lock Waits / Sec
• Locks: Lock Timeouts/sec
• Locks: Number of Deadlocks/sec
• SQL Statistics: Batch Requests/Sec
• SQL Statistics: SQL Re-Compilations/sec
• SQL Statistics: SQL Compilations/sec

9. Checking Execution Plan with SSMS

10. Actual Execution Plan in SQL Server

11. IO Statistics
• Copy message into http://www.statisticsparser.com/
• Logical reads is the most prominent counter

12. Indexing

13. Indexing
• Clustered index
• Primary Key: Includes all columns
• Non-clustered index
• One or more columns: Include as many columns as needed
• SELECT * FROM Device WHERE Serial = ‘0123456789’
• Execution plan suggests to add:
• CREATE NONCLUSTERED INDEX (…) ON Device (Serial)

14. Indexing (cont.)
• A new index is a new copy of the table, containing “key columns”
and “include columns”
• 4,516 logical read
• SSMS hints:
• Logical reads decreases to 13

15. Indexing (cont.)
• Indexing helps
• SELECT item using COLUMN = VALUE
• COLUMN compare VALUE
• INDEX name on table (a, b)
• Sort on a values, then b values in each bucket on a
• Not good for
• SELECT id FROM table WHERE a > 100 and b = 200
• SELECT id FROM table WHERE b = 200
• Good for
• SELECT id FROM table WHERE b > 100 and a = 200
• SELECT id FROM table WHERE a > 100

16. Investigating index usage (index_usage_stats)
• SELECT OBJECT_NAME(ddius.[object_id], ddius.database_id) AS [object_name] ,
ddius.index_id ,
ddius.user_seeks ,
ddius.user_scans ,
ddius.user_lookups ,
ddius.user_seeks + ddius.user_scans + ddius.user_lookups
AS user_reads ,
ddius.user_updates AS user_writes ,
ddius.last_user_scan ,
ddius.last_user_update
FROM sys.dm_db_index_usage_stats ddius
WHERE ddius.database_id > 4 -- filter out system tables
AND OBJECTPROPERTY(ddius.OBJECT_ID, 'IsUserTable') = 1
AND ddius.index_id > 0 -- filter out heaps
ORDER BY ddius.user_scans DESC

17. Identify indexes that have never been
accessed
• SELECT OBJECT_NAME(i.[object_id]) AS [Table Name] , i.name FROM
sys.indexes AS I INNER JOIN sys.objects AS o ON i.[object_id] =
o.[object_id] WHERE i.index_id NOT IN ( SELECT ddius.index_id
FROM sys.dm_db_index_usage_stats AS ddius
WHERE ddius.[object_id] = i.[object_id] AND i.index_id =
ddius.index_id AND database_id = DB_ID() ) AND o.[type] = 'U‘
ORDER BY OBJECT_NAME(i.[object_id]) ASC

18. Tune Your Indexing Strategy with SQL Server
DMVs
• https://www.simple-talk.com/sql/performance/tune-your-indexing-
strategy-with-sql-server-dmvs/

19. Database Engine Tuning Advisor

22. SQL Server Profiling

23. Some Columns in DB are Locked!
• Use sp_who2 and check BlkBy to see who has blocked whom
• sp_whoisactive does it in a better way

24. SQL Server Profiler

25. Profile Using Execution Plan Cache
• Install sp_BlitzCache
• Run: sp_blitzcache @sort_order = 'reads', @top = 20
• You will find “Query Text”, “Total Reads”, “# Executions”, “Execution Plan”,
and some hints about how to improve performance of those queries.
• It gave us a hint to add the following index:
• We thought indexing this table is not important since it is solely used in
admin panel. But sp_BlitzCache tells that 20% of reads are related to this
function.

26. Other Diagnosing Stored Procedures
• sp_BlitzIndex: Gives you hints on how much your indexes are used and
suggestions for new indexes and their estimated effect
• sp_Blitz: Checks common health measures of your DB
• sp_AskBrent: For 5 seconds watches your DB and gives you a report on:
• Blocking or long-running queries
• If a backup, DBCC, or index maintenance job was running
• Query wait statistics to figure out SQL Server’s current bottleneck
• Perf. counters for CPU use, slow drive response times, or low Page Life Expectance
• You can create an agent job which runs sp_AskBrent every 15 minutes and
appends the result to a table in your DB (more info)
• All these stored procedures are packaged in the ZIP file containing
sp_BlitzCache

27. Evidences of Effect!
• # of lock requests / sec
• Avg. wait time
• CPU usage

28. Questions?