Practical SQL Server Performance Monitoring & Optimization

1. Practical SQL Server Performance Monitoring & Optimization Anil Desai http://AnilDesai.net Austin CodeCamp 2010

2. Speaker Information • Anil Desai • Independent consultant (Austin, TX) • Author of numerous IT books • Instructor, “Implementing and Managing SQL Server 2005” (Keystone Learning) • Info: http://AnilDesai.net or Anil@AnilDesai.net

3. Agenda and Overview • Performance Monitoring Overview • Monitoring Database Servers • Using SQL Profiler • Using the Database Engine Tuning Advisor • Application Design Tips • Managing Processes, Locking, and Deadlocks

4. Performance Monitoring Overview Developing processes and approaches for performance optimization

5. Performance Monitoring Approaches • Best Practices: • Optimize for real-world workloads • Monitor/review performance regularly • Focus on specific issues

6. Overview of Performance Monitoring Tools and Methods

7. Monitoring and Troubleshooting Scenarios

8. Monitoring SQL Server Using SQL Server tools and features to monitor database activity

9. Windows Performance Monitor • Available in all current versions of Windows • Statistics are organized into: • Objects • Counters • Instances • Data Collector Sets • Windows Vista / Windows 7 / Windows Server 2008 • Used to report on performance data that is collected over time • Includes built-in System Diagnostics and System Performance collectors and reports

10. General Statistics Logins | logouts / sec User Connections Latches Latch waits / sec Locks Lock requests / sec Lock waits / sec Memory Manager Everything! Replication Depends on configuration SQL Statistics Batch requests / sec SQL compilations / sec Useful SQL Server Performance Counters • Backup Device • Device throughput Bytes/sec • Buffer Manager • Buffer cache hit ratio • Page reads / sec • Buffer Partition • Free Pages • Cache Manager • Cache Hit Ratio • Databases • Active Transactions • Data File Size • Log Growths • Percent Log Used • Transactions / sec Anil Desai

11. SQL Server Management Studio Reports • SQL Server Activity Monitor • Provides a quick overview of database server activity • CPU, Processes, Resource Waits and Disk I/O • “Recent Expensive Queries” • SQL Server Management Studio Reports • Quick overview of SQL Server usage • Can export to Excel or PDF

12. SQL Server Report Examples • Server Dashboard • Memory Consumption • Activity – All Block Transactions • Activity – Top Sessions • Performance – Batch Execution Statistics • Performance – Top Queries by Average CPU • Object Execution Statistics • Disk Usage • All Transactions • All Blocking Transactions • Index Usage Statistics • Top Transactions by Age • Schema Changes History Server-Level Reports Database-Level Reports

13. Monitoring SQL Server Logs • Windows Event Logs / Event Viewer • Application and System Event Logs • SQL Server Management Studio • SQL Server Logs • Can configure max. # of log files • SQL Server Agent Error logs • Can configure logging levels (Errors, Warnings, Information) • Using the Log File Viewer • Can Export / Load log information • Can search for specific errors/messages

14. Using Dynamic Management Views (DMVs) • Purpose: • Monitoring and troubleshooting • View server state and performance details • Returns relational result sets (use standard SELECT statements) • Full list can be viewed in “Views  System Views” section of the properties of the database • Scopes: • Server level • Database level

15. DMV Examples

16. Using SQLDiag • Data Collected: • System Information (MSINFO) • Windows Event Logs • SQL Server configuration • Command-Line Utility (SQLDiag.exe) • Stores output to files • Configuration file: SQLDiag.xml • Can run as a service (/R) • Can run in continuous mode

17. Using SQL Profiler Monitoring SQL Server Activity

18. Understanding SQL Profiler • Purpose / Features: • GUI for managing SQL Trace • Monitor important events • Capture performance data / resource usage • Replaying of workloads / transactions • Identifying performance bottlenecks • Correlation of data with System Monitor • Workloads for Database Tuning Advisor • Examples: • Generate a list of the 100 slowest queries • Monitor all failed logins (Security)

19. SQL Server Profiler Architecture • SQL Profiler Terminology • Trace Definitions • Events • Columns • Filters • Creating and Managing SQL Traces • SQL Profiler (GUI) • System Stored Procedures (Transact-SQL) • Trace Templates (Built-In) • Standard (Default), SP_Counts • TSQL, TSQL_Duration, TSQL_Grouped,TSQL_Replay, TSQL_SPs • Tuning

20. SQL Profiler Terminology • Trace • A set of events, data columns and filters that specify what data should be collected • Data can be saved to a file or a database table • Trace File • Trace data that is saved to a binary file • Default extension is “.trc” • Trace Table • A SQL Server database table in which trace information is stored • Profiler will automatically create the structure of this table when you start running a new trace • Trace Template • Saved specifications that can be used as the basis for new traces • E.g., an environment may have a “Security Monitoring template”, a “CRM Application Performance”, etc. • Default extension is “.tdf” Anil Desai

21. Configuring Trace Events • Groupings: • Event Categories • Event Classes • Events • Examples: • TSQL • Stored Procedures • Performance • Errors and Warnings • Security auditing

22. Configuring Trace Columns • Specifies the details to be monitored/recorded • Configuring columns • Columns can be ordered and grouped • Values can be filtered • Examples of Columns: • StartTime / EndTime • TextData • Duration • Resource Usage (CPU, Reads, Writes) • Information: User, Database, App. Names

23. Trace Output Options • Interactive • Good for “live” monitoring of small sets of data • Trace Files (*.trc) • Can enable file rollover based on size • “Server processes trace data” option • Trace table • Will automatically create the table • Can set maximum number of rows • Scheduling of traces (stop time)

24. Demo: Creating Profiler Traces • Launching SQL Profiler • Connecting to a database instance • Configuring output options • Create a trace definition • Specifying events, columns, and filters • Running and viewing a trace

25. Other SQL Profiler Options • Creating new templates using SQL Profiler • Scripting trace definitions • sp_trace_create • sp_trace_setfilter • sp_trace_GenerateEvent • sp_trace_SetEvent • sp_trace_SetStatus • Extracting SQL Server Events • Transact-SQL Events • ShowPlan Events • Deadlock Events

26. Using System Monitor with SQL Profiler • Purpose / Goal: • Correlate server performance with database performance • Process: • Define and start a counter log • Define and start a SQL Profiler trace • Import Performance Data in SQL Profiler • Required Trace properties • StartTime • EndTime

27. Using the Database Engine Tuning Advisor Analyzing workloads to optimize physical database structures

28. Database Engine Tuning Advisor • Reviews sample workloads and makes performance recommendations • Evaluates Physical Design Structures (PDS) • Indexes (clustered, non-clustered) • Indexed Views • Partitions • Numerous analysis options • Output • Generates modification scripts • Generates Reports for later analysis

29. Workload Sources • Files • Transact-SQL Files • XML Files • Should represent commonly-used queries • SQL Profiler Trace Files / Tables • Use Tuning built-in trace template • Events: • Transact-SQL Batch • Remote Procedure Call (RPC) • Columns: Event Class and Text Data

30. DTA Execution Options • Limit tuning time • Tuning Options • Allowed Physical Design Structures (PDS) • Keep all/specific existing objects • Maximum storage space • Online or offline recommendations • Partitioning

31. DTA Reports • Reports can be exported to XML files • Report Examples:

32. Using the Database Engine Tuning Advisor • Process: • Generate a workload (file or table) • Select tuning options • Run the analysis • View reports • Save and/or apply recommendations • Running the DTA: • Database Engine Tuning Advisor Application (GUI) • Dta.exe command-line utility

33. Application Design Tips Practical ways to improve database application performance

34. Application Design Tips • Create an abstraction layer between the database and the presentation code • Separates presentation and logic (esp. in Web Apps) • Example: ADO.NET Datasets • Database design: • Understand typical use-cases before designing the database • Create and enforce naming conventions • Balance write (OLTP) and read (reporting) performance requirements • Use strategic denormalization Anil Desai

35. Application Design Tips (cont’d.) • Never include actions that require user input within a transaction • Use connection pooling, whenever possible • Open connections late and close them early • Avoid unnecessary server round-trips • Use client-side caching whenever possible • Optimistic concurrency • Pessimistic concurrency • Distribute processing • Some operations are more efficient on the DB server (e.g., aggregations, sorting, etc.)

36. Managing Processes, Locking, and Deadlocks Troubleshooting common SQL Server performance problems

37. Understanding Processes • Processes • Interactive users • SQL Server Management Studio • Applications (Connection Pooling) • SQL Profiler • Database Engine Tuning Advisor • Replication • Service Broker • Process IDs < 50 are system-related

38. Monitoring Processes • SQL Server Activity Monitor • Processes (connected users) • Locks (by Process / by Object) • Filtering options • Auto-refresh option • System Stored Procedures / Views • Sys.DM_Exec_Sessions • Sys.DM_Exec_Requests • Sys.SysProcesses • sp_who / sp_who2

39. Managing Processes • Process Information • Current Process ID: @@SPID • Session Options: DBCC USEROPTIONS • Killing Processes • KILL ProcessID [WITH STATUSONLY] • Viewing Last Activity • DBCC INPUTBUFFER(ProcessID) • DBCC OUTPUTBUFFER(ProcessID)

40. Understanding Locking • Coordinates multiple accesses to the same data • Ensures ACID Properties for transactions (Atomic, Consistent, Independent, Durable) • Contention can reduce performance • Locking granularity: • Row-Level, Page-Level, Table-Level, etc. • Lock Modes: • Shared, Exclusive, etc. • Lock escalation

41. Understanding Blocking • Blocking • When transaction(s) must wait for a lock on a resource • LOCK_TIMEOUT setting (default = wait forever) • Locking Models: • Pessimistic • Optimistic

42. Transaction Isolation Levels • Balance of concurrency (performance) vs. consistency • Affects SELECT queries • SET TRANSACTION ISOLATION LEVEL • Transaction Isolation Levels • READ UNCOMMITTED • READ COMMITTED (default) • REPEATABLE READ • SERIALIZABLE • SNAPSHOT • Row-Versioning: • ALLOW_SNAPSHOT_ISOLATION • READ_COMMITTED_SNAPSHOT

43. Monitoring Locking Activity • Activity Monitor • SQL Profiler • Locks Event Category • System Monitor: • SQL Server  Locks Object • System Views • Sys.DM_Tran_Locks • Sys.DM_Exec_Requests • System Stored Procedures • sp_Lock

44. Understanding the Deadlock Process • Deadlocks: • Two or more tasks permanently block each other based on resource locks • Default resolution is within 5 seconds • Deadlock victim • Transaction is rolled-back • Process receives a 1205 error • Example: • Process 1 locks the Customers table and requires access to the Orders Table • Process 2 locks the Orders table and requires access to the Customers Table

45. Avoiding Deadlocks • Minimize transaction times • Commit / Rollback transactions as quickly as possibly • Avoid user-related time within a transaction • Access objects in a consistent order • Change the transaction isolation level • Use a lower level isolation level, if appropriate • Use snapshot-based isolation levels

46. Deadlock Victims • Deadlock priorities: • SET DEADLOCK_PRIORITY (LOW, NORMAL, HIGH, integer) • Deadlock resolution: • Lower priority is killed first • If equal priorities, least expensive transaction becomes the victim • Application or user should attempt to re-run the transaction

47. Monitoring Deadlocks • SQL Server Error Log • SQL Profiler • Locks Event Category • Lock:Deadlock Chain • Lock:Deadlock • Deadlock Graph • Events Extraction Trace Property • Export deadlock XML (.xdl) file • Viewing Deadlock Files • SQL Server Management Studio (File  Open  SQL Deadlock Files (*.xdl)

48. Deadlock Graph

49. Questions & Discussion For more information: http://AnilDesai.netAnil@AnilDesai.net