Cache issues from T-SQL-generated plans and how to manage them. Webcast by Richard Douglas. To view the recorded webcast, click here:http://dell.to/1fVgKSp Looking for a foolproof way to improve SQL Server performance? You’ll find it by intelligently managing cashed plans that T-SQL code generates. T-SQL code is different from many other languages; you tell it "what" to do and the optimisation engine interprets that command into "how" to do it, then files that information away. Join Dell SQL Server experts as they explain the concepts that support the storage of these “how-to” plans, ways to determine what has been stored, and how to create efficiency at both the database and all-important server level. This educational session will cover: •Concepts behind cashed plans •How to find out what’s been stored •How to create efficiencies at both query and server levels •And much more

1. Managing SQL Server’s Plan
Cache
Richard Douglas

2. Agenda
• Introductions
• What is the plan Cache?
• Plan Cache Memory Usage
• Finding problem plans in the cache
• Events near you
• Q&A
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3. Your host
• Richard Douglas
• Systems Consultant
• SQL Server MCITPro
• Maidenhead SQL User Group Leader
• Blog: http://SQL.RichardDouglas.co.uk
• Twitter: @SQLRich
• Email:
Richard.Douglas@Software.Dell.com
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4. What is the plan
cache?
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5. Query optimization explained simply
1.
Query submitted
2. Magic happens
3. Shedload of data returned
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6. Plan cache simplified
Query submitted
Stored in
memory
Doesn’t exist
Compile
Check for plan in
cache
The more
plans, the longer
this takes. Be
mindful of “cache
Exists bloating”
Run with plan
CPU Intensive
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7. Recompilation Process
From “Plan Caching
in SQL Server 2008”
by Greg Low
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8. Finding Compiles / Recompiles
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9. (Re)Compile Tip
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10. Call & Hit Rates in SoSSE
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11. Recompilations
• If schema changes are made to any dependencies of code then a
recompilation will occur. This includes:
–
–
–
–
Tables
Views
Procedures
Indices
• Reaching statistics thresholds:
• An explicit call to sp_recompile.
• Executing a stored procedure using the WITH RECOMPILE option.
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12. Plan
Cache
Memory
Usage
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13. Plan Cache Memory Usage
SQL Server Version
Cache Pressure Limit
SQL Server 2012, SQL Server 2008 and SQL 75% of visible target memory from 0-4GB +
Server 2005 SP2
10% of visible target memory from 4Gb64GB + 5% of visible target memory > 64GB
SQL Server 2005 RTM and SQL Server 2005 75% of visible target memory from 0-8GB +
SP1
50% of visible target memory from 8Gb64GB + 25% of visible target memory >
64GB
SQL Server 2000
SQL Server 2000 4GB upper cap on the plan
cache
32gb = 5.8gb cache
64gb = 9gb cache
128gb = 12.2gb cache
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14. Ageing out plans
Cost = I/O cost + context switch cost (a measure of CPU cost) +
memory cost
The individual parts of the cost are calculated as follows.
• Two I/O’s cost 1 tick,
maximum of 19 ticks.
• Two context switches cost 1 tick,
maximum of 8 ticks.
• Sixteen memory pages (128 KB) cost 1 tick,
maximum of 4 ticks.
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15. Finding problem
plans in the
cache
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16. Finding Problem Plans in the Cache
In this section:
• Examples of cache bloat
• Finding IO intensive queries
• Finding CPU Intensive queries
• Looking for certain plan operations
• Looking at Individual plans
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17. Summary
• The reason for the plan cache.
• Monitoring the plan cache.
• Plan cache memory utilisation.
• Demonstrated how to find:
– Cache bloat
– Particular operators
– High resource queries
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18. Solution Area
Product
Description
Fast, flexible backup and
recovery with industry-leading
compression technology
Backup and
Recovery
Product Offerings
Discover and resolve
performance issues in production
before they impact end users and
service levels
Performance
& Operations
Deepest possible understanding
of database performance and
norms
Performance
Tuning
Plan and develop applications
that deliver both functionality and
Development
optimal performance
Comprehensive schema, object,
security and change
management
Administration
Community,
Knowledge,
Training
Free !!!
Project
Lucy
SpotlightEssentials.com
© 2012 Quest Software Inc. All rights reserved.
Community crowdsourcing for
SQL Server tracing, health
checks and performance
Pg. 18
information!

19. SQLRelay Dates










@SQLRelay2013
11/11/13 – Reading
12/11/13 – Southampton
13/11/13 – Cardiff
14/11/13 – Birmingham
15/11/13 – Hemel Hempstead
25/11/13 – Newcastle
26/11/13 – Manchester
27/11/13 – Norwich
28/11/13 – Bristol
29/11/13 – London

20. SQL Rally
Stockholm (Sweden): 4-6th Nov
Amsterdam (Holland): 6 – 8th Nov
http://www.sqlpass.org/sqlrally/2
013/nordic/Home.aspx
http://www.sqlpass.org/sqlrally/2
013/amsterdam/Home.aspx
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21. What Do Developers Need to Know About
SQL Server?
Join Microsoft Certified Master Brent Ozar & Richard Douglas:
The database comes with a manual, but let's be honest: nobody's got
time for that. Database administrators - let's distill the most important
concepts and rules for developers down to 140-character chunks on
Twitter on Thursday, October 24th from 10AM to 11AM Eastern.
Microsoft Certified Master Brent Ozar will lead the discussion at
#dellsql.
Register now - http://bit.ly/H6XeDU
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22. What would you like to see?
• Always On Availability Groups
• Backups
• Clustering
• Database Mirroring
• Performance Monitoring
• Performance Tuning
• Installation & Configuration
• Best Practices
– DBA
– Developer
• Indexing
• Baselining
• SSAS
• SSIS
• SSRS
Next Webcast: 19th November 2013
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23. Any questions?
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24. Thank you for attending
Richard Douglas
Richard.Douglas@Software.Dell.com
@SQLRich