A brief of some SQL base advices in order to keep your DB more accurate, optimized and safe.

1. XII Encontro da comunidade SQLPort

2.  Name: Gonçalo Chaves
 Alias: Chaves
 Job: Senior Analyst
 Company: Viatecla
 Im: evolution69@msn.com
 Tw: @gchaves
 Hobbies: reading, photo, gaming
 Email: gchaves@viatecla.com
 Communities: xamlpt, pontonetpt, sqlport

3. “The biggest problem in databases is
the base data…”

4.  Main challenges
 Why we don’t care
 Analysis and procedures
 Tools
 Use Cases
 References

5.  Engineers knows programing but they don’t
know SQL!

6.  Rookies don’t thing in scalability!

7.  High availability
 Scale and Scale
 Trustful transactions
 Performance and tuning
 Maintenance and archiving
 Partitioning
 Data integrity

8.  The easy path
 Comfort, learning is a painful process
 No professional training
 No time!
 The big truck rule
 Scale and trust aren’t known
 “Microsoft’s lema”

9.  Don’t know the engine
 Wrong Assumptions
 Re-use views, queries, with no limits
 Data type? What? nvarchar don’t fit in all?
 Unknown Transaction Isolation levels
 Tons of locks on a single query

10.  Normalization
 Careful to much can be inefficient
 Appropriate Keys and Indexes
 Right Primary and FK’s
 Choose for relations and integrity

11.  Don’t over on Indexes
 Take’s disk space
 Drop index for bulk insertion
 Some WHERE’s clauses can’t take advantage on ix
 Evaluate and test you ix

12.  Each Database is a Database
 BETWEEN can be more efficient than operators
 Native functions (Convert, format…)
 Aggregate functions (max, min, count, …)

13.  The NULL cancer… you must know NULL well
 ISNull can be a painful
 Wrong assumption on fields
 Null datatype vs “Null”
 Non safe transaction
 Logic looseness

14.  My debug:
 Profiler… yeah it’s heavy but it’s useful!
 TA – tuning advisor
 Activity monitor
 Look for index, keys, fragments,

15.  Daily, every sql dev is also an sql admin!
 RedGate suite
 QueryExpress (light, keep simple)
 TableDiff.exe
 DMVStats (dataware house)
 SQL Server Cache manager

16.  DBA? Where?
 SQL Internals Viewer
 SQLQueryStress (in dev or stage scenarios)
 SQLIO Disk Benchmark tool (on server)

17.  SQL Security
 Roles may be insufficient
 Prevent SQL injection
 Prevent non logic queries that can burn your data
 Remember, it’s more easier broke sql security by
your app than anything else.

18.  The devil ….
SELECT *

19.  Dam accelerators ….
 ADO.NET
 SQLDATASOURCE
 LINQ to SQL
 Entity Framework …

20.  Abuses on
 Group by ; Having; Inner join
 Sub queries with sub queries with …
 #temp_table for everything…
 DML cmd’s
 Constraints for everything…

21.  Good sense
 Know your data 5
 Maintenance 4
 Job your data 3 Frag
 Integrity vs Performance 2 Perf
Disk
1
 The balance is the key
0
Jan Fev Mar April May June

22.  Database – xpto
 1500 tables
 2700 stored procedures
 ~1.5 M transaction per day
 Delete in cascade …
 Broke process
 Restart server

23.  Normalize has needed
 Test your database
 Schedule jobs
 Create Index’s where needed
 Use right tools
 full text search, TA, SSIS

24.  Avoid triggers
 Partitioning
 Archive data
 Data type right usage
 Think in your transaction mode
 Use safe locks
 Test, application stress and faulty

25.  Document you DB 
 Keep scripts in safe
 Update your scripts
 Use facts not assumptions
 Cross your test with others
 Right lock safe usage
 Define db architecture

26.  A good DB start’s on your apps
 Cache is more than welcome
 “The 4 connections challenge..”
 Multiple Environments keep DB’s updated
 Keep your analysis update

27.  Developers exists in C# not in SQL – Deal with it!
 Train your team – code review; sessions; books
 Use the right tools on right scenarios
 Integrity vs Performance
 Keep in mind security concerns
 Make Maintenance plans – from the beginning

28.  Usual blog’s / Communities
 SQL 2008 internals
 Write Smart Sql
 SQL For Smarties
 Sql forums … sqlport 

29.  Thank you all 
 Do right SQL before the pain!
 Follow me at:
http://pontonetpt.org/blogs/chaves
http://xamlpt.com/blogs/chaves
 gchaves@viatecla.com
 www.viatecla.com