Book Chapter on Improving SQL Server Performance

 

Book Chapter on Improving SQL Server Performance

I stumbled upon a great document on how to improve SQL Server performance. It's actually a chapther in a book on "Improving .NET Application Performance and Scalability" from a "Patterns and Practices" prescriptive guidance. Here's a summary of what it covers:

• SQL: Scale Up vs. Scale Out
  • Optimize the application before scaling up or scaling out.
  • Address historical and reporting data
  • Scale up for most applications.
  • Scale out when scaling up does not suffice or is cost-prohibitive.
• Schema
  • Devote the appropriate resources to schema design.
  • Separate OLAP and OLTP workloads.
  • Normalize first, denormalize for performance later.
  • Define all primary keys and foreign key relationships.
  • Define all unique constraints and check constraints.
  • Choose the most appropriate data type.
  • Use indexed views for denormalization.
  • Partition tables vertically and horizontally.
• Queries
  • Know the performance and scalability characteristics of queries.
  • Write correctly formed queries.
  • Return only the rows and columns needed.
  • Avoid expensive operators such as NOT LIKE.
  • Avoid explicit or implicit functions in WHERE clauses.
  • Use locking and isolation level hints to minimize locking.
  • Use stored procedures or parameterized queries.
  • Minimize cursor use.
  • Avoid long actions in triggers.
  • Use temporary tables and table variables appropriately.
  • Limit query and index hints use.
  • Fully qualify database objects.
• Indexes
  • Create indexes based on use.
  • Keep clustered index keys as small as possible.
  • Consider range data for clustered indexes.
  • Create an index on all foreign keys.
  • Create highly selective indexes.
  • Consider a covering index for often-used, high-impact queries.
  • Use multiple narrow indexes rather than a few wide indexes.
  • Create composite indexes with the most restrictive column first.
  • Consider indexes on columns used in WHERE, ORDER BY, GROUP BY, and DISTINCT clauses.
  • Remove unused indexes.
  • Use the Index Tuning Wizard.
• Transactions
  • Avoid long-running transactions.
  • Avoid transactions that require user input to commit.
  • Access heavily used data at the end of the transaction.
  • Try to access resources in the same order.
  • Use isolation level hints to minimize locking.
  • Ensure that explicit transactions commit or roll back.
• Stored Procedures
  • Use Set NOCOUNT ON in stored procedures.
  • Do not use the sp_ prefix for custom stored procedures.
• Execution Plans
  • Evaluate the query execution plan.
  • Avoid table and index scans.
  • Evaluate hash joins.
  • Evaluate bookmarks.
  • Evaluate sorts and filters.
  • Compare actual versus estimated rows and executions.
• Execution Plan Recompiles
  • Use stored procedures or parameterized queries.
  • Use sp_executesql for dynamic code.
  • Avoid interleaving DDL and DML in stored procedures, including the tempdb database DDL.
  • Avoid cursors over temporary tables.
• SQL XML
  • Avoid OPENXML over large XML documents.
  • Avoid large numbers of concurrent OPENXML statements over XML documents.
• Tuning
  • Use SQL Profiler to identify long-running queries.
  • Take note of small queries called often.
  • Use sp_lock and sp_who2 to evaluate blocking and locking.
  • Evaluate waittype and waittime in master..sysprocesses.
  • Use DBCC OPENTRAN to locate long-running transactions.
• Testing
• Monitoring
  • Keep statistics up to date.
  • Use SQL Profiler to tune long-running queries.
  • Use SQL Profiler to monitor table and index scans.
  • Use Performance Monitor to monitor high resource usage.
  • Set up an operations and development feedback loop.
• Deployment Considerations
  • Use default server configuration settings for most applications.
  • Locate logs and the tempdb database on separate devices from the data.
  • Provide separate devices for heavily accessed tables and indexes.
  • Use the appropriate RAID configuration.
  • Use multiple disk controllers.
  • Pre-grow databases and logs to avoid automatic growth and fragmentation performance impact.
  • Maximize available memory.
  • Manage index fragmentation.
  • Keep database administrator tasks in mind.

If you like the summary, read the entire 32 pages from
http://msdn.microsoft.com/en-us/library/ms998577.aspx

Jose Barreto's Blog : Book Chapter on Improving SQL Server Performance