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Anil Desai Austin CodeCamp 2008 Anil Desai ◦ Independent consultant (Austin, TX) ◦ Author of several SQL Server books ◦ Instructor, “Implementing and Managing SQL Server 2005” (Keystone Learning) ◦ Info: http://AnilDesai.net or [email protected] I. Performance Monitoring Overview II. Monitoring SQL Server III. Using SQL Profiler IV. Using the Database Engine Tuning Advisor V. Managing Processes, Locking, and Deadlocks Developing processes and approaches for performance optimization Establish a baseline Repeat (if desired) Best Practices: ◦ Identify bottlenecks ◦ ◦ Measure performance Make one change at a time Optimize for real-world workloads Monitor/review performance regularly Focus on specific issues System/OS • Windows System Monitor • Alerts (Performance-Based) SQL Server • SQL Profiler / SQL Trace • Activity Monitor / SQL Server Agent Alerts • Dynamic Management Views (DMVs) QueryLevel • Database Engine Tuning Advisor • Query Execution Plans Using various SQL Server features to monitor database activity Overviews of SQL Server usage Server-Level Report Examples: ◦ Can export to Excel or PDF ◦ ◦ ◦ ◦ ◦ ◦ ◦ Server Dashboard Memory Consumption Activity – All Block Transactions Activity – Top Sessions Performance – Batch Execution Statistics Performance – Top Queries by Average CPU Object Execution Statistics Examples: ◦ ◦ ◦ ◦ ◦ ◦ Disk Usage All Transactions All Blocking Transactions Index Usage Statistics Top Transactions by Age Schema Changes History New reports added in Service Packs ◦ Ability to use custom reports 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 Purpose: ◦ Monitoring and troubleshooting ◦ View server state and performance details ◦ Returns relational result sets Scopes: ◦ Server level ◦ Database level Examples: ◦ Database Engine Sys.DM_DB_File_Space_Usage ◦ Indexes Sys.DM_DB_Index_Operational_Stats Sys.DM_DB_Index_Physical_Stats ◦ I/O Related Sys.DM_IO_Pending_IO_Requests Sys.DM_IO_Virtual_File_Stats ◦ Common Language Runtime ◦ Database Mirroring ◦ Transactions 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 Monitoring SQL Server Activity 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) SQL Profiler Terminology ◦ ◦ ◦ ◦ Trace Definitions Events Columns Filters Creating and Managing SQL Traces Trace Templates (Built-In) ◦ SQL Profiler (GUI) ◦ System Stored Procedures (Transact-SQL) ◦ Standard (Default), SP_Counts ◦ TSQL, TSQL_Duration, TSQL_Grouped,TSQL_Replay, TSQL_SPs ◦ Tuning Groupings: ◦ Event Categories ◦ Event Classes ◦ Events Examples: ◦ ◦ ◦ ◦ ◦ TSQL Stored Procedures Performance Errors and Warnings Security auditing Event Categories Event Classes Events Specify the details to be recorded 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 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) 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 Creating new templates Scripting trace definitions Extracting SQL Server Events ◦ Transact-SQL Events ◦ ShowPlan Events ◦ Deadlock Events 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 Can monitor local or remote computers Performance Statistics: ◦ Objects ◦ Counters ◦ Instances Modes: ◦ System Monitor ◦ Performance Logs and Alerts Counter Logs Trace Logs Alerts Analyzing workloads to optimize physical database structures Can make performance-related recommendations Replaces the “Index Tuning Wizard” Evaluates Physical Design Structures (PDS) Numerous analysis options Output ◦ Indexes (clustered, non-clustered) ◦ Indexed Views ◦ Partitions ◦ Generates modification scripts ◦ Generates Reports for later analysis 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 Limit tuning time Tuning Options ◦ ◦ ◦ ◦ ◦ Allowed Physical Design Structures (PDS) Keep all/specific existing objects Maximum storage space Online or offline recommendations Partitioning Reports can be exported to XML files Report Examples: Workload analysis Column access Statement cost Table access Event frequency View-Table Relations Index Usage (current / recommended) 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 Troubleshooting common SQL Server performance problems 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 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 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) 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 Blocking ◦ When transaction(s) must wait for a lock on a resource ◦ LOCK_TIMEOUT setting (default = wait forever) Locking Models: ◦ Pessimistic ◦ Optimistic Balance of concurrency (performance) vs. consistency ◦ Affects SELECT queries ◦ SET TRANSACTION ISOLATION LEVEL Transaction Isolation Levels ◦ ◦ ◦ ◦ READ UNCOMMITTED READ COMMITTED (default) REPEATABLE READ SERIALIZABLE Row-Versioning: ◦ ALLOW_SNAPSHOT_ISOLATION ◦ READ_COMMITTED_SNAPSHOT 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 Deadlocks: Deadlock victim Example: ◦ Two or more tasks permanently block each other based on resource locks ◦ Default resolution is within 5 seconds ◦ Transaction is rolled-back ◦ Process receives a 1205 error ◦ 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 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 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 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) Resources from Anil Desai ◦ Web Site (http://AnilDesai.net) ◦ E-Mail: [email protected] ◦ ReportingServicesGuru.com ◦ Keystone Learning Course: “Microsoft SQL Server 2005: Implementation and Maintenance (Exam 70-431)”
