Advanced Tuning: Unconventional Solutions to Everyday Problems Robert L Davis

Who am I?

Advanced Tuning: What is Tuning? Finding poor performance and making it better. Ensuring that the server is configured for optimal performance. Making use of the tools available to you find hidden problems and resolve them.

Advanced Tuning: Tools SQL Trace/Profiler (please dont use Profiler in production) Performance Monitor SQLDiag/PSSDiag SQLNexus RML Utilities PAL Tool Database Engine Tuning Advisor (DTA) SQLIO DMVs SQL Error Log Your creativity

Advanced Tuning: Tools SQL Trace/Profiler – Captures SQL activity Find out what is occurring internally in SQL Server Output to a trace file Profiler can correlate a trace file and a Performance Monitor file by time Performance Monitor – Captures server activity Find out what is occurring at the server level Output to a file SQL counters can be captured via sys.dm_os_performance_counters

Advanced Tuning: Tools SQLDiag/PSSDiag – Collects a variety of diagnostic data Windows Performance Logs Windows Event Logs SQL Traces SQL blocking info SQL Configuration info SQLNexus – Analyzes SQLDiag/PSSDiag data Creates easy to interpret reports and graphs Finds most expensive queries in trace files Provides details on resource waits statistics

Advanced Tuning: Unconventional Solutions to Everyday Problems

Advanced Tuning: Tools RML Utilities – Diagnoses SQL Server Performance data ReadTrace – consumes trace files Reporter – provides easy to understand reports on trace data consumed using Readtrace OStress – replays and stress tests queries ORCA – Ostress replay control agent PAL Tool – Performance Analysis of Logs Creates easy to read and understand graphs from Performance Monitor files Color codes graphs based on known thresholds to easily identify possible bottlenecks Requires Microsoft Chart Controls for.NET Framework 3.5

Advanced Tuning: Unconventional Solutions to Everyday Problems

Advanced Tuning: Tools Database Engine Tuning Advisor (DTA) Formerly Index Tuning Wizard Performs in-depth index analysis Can be based on a single query or a full trace file or work file Can perform What if? analysis to verify recommendations Limited in scope SQLIO – Determines I/O capacity of storage Should be used to verify I/O capabilities before deploying SQL to the storage Validates storage I/O capabilities through stress testing Not the simplest tool to learn Great tutorial by Brent Ozar on SQL Server Pedia:

Advanced Tuning: Tools DMVs – provides insight into the internal statistics and structures of SQL Server Developed to make troubleshooting easier SQL Team developers were challenged to try to fix bugs by only using data readily available to administrators DMVs for troubleshooting everyone should know: sys.dm_os_wait_stats – overall wait statistics for the server. Most are cumulative sys.dm_os_waiting_tasks – wait statistics for active tasks currently executing sys.dm_os_performance_counters – all SQL Server performance counters available to Performance Monitor also found here sys.dm_db_index_usage_stats – statistics on how your indexes are being used sys.dm_exec_cached_plans – query plans in the plan cache sys.dm_exec_sql_text – text of a query based on the sql handle. Joined to other DMVs to get the exact text to which they are referring sys.dm_os_buffer_descriptors – statistics on how the memory areas in the buffer pool are allocated sys.dm_exec_query_memory_grants – statistics on how much memory is allocated to individual queries or what memory grants are pending sys.dm_exec_requests – the current requests on the server sys.dm_exec_sessions – the current sessions on the server Glenn Berrys DMV a day series: dmv-a-day-series.aspx

Advanced Tuning: Tools SQL Error Log – error and other important information Wealth of information about alerts and errors occurring in SQL Server that may not be reported through any other means Very useful for capturing deadlock information via trace flags 1204 and 1222 Reports I/O freezing and excessive waits for I/O requests Reports when a torn page is recovered from a mirroring partner Your creativity – dont be afraid to think out of the box

Unconventional Solution to Everyday Problems Scenario: CPU utilization spikes No pattern to when they occur Are short term (< 10 min.) and disappear before operations personnel can react Performance critical production server Users are affected by the CPU spikes Solution: run a custom SQL trace automatically as soon as a CPU spike is detected and capture top 50 CPU consuming queries. This solution can be adapted to respond to any performance criteria that you can measure

Advanced Tuning: Unconventional Solutions to Everyday Problems

Unconventional Solution to Everyday Problems Scenario: How to measure replication latency without tracer tokens Replication latency can spike to high latency at times Tracer tokens not effective when latency is high Data freshness critical replication servers Monetary decisions based on replicated data Solution: query the Replication Monitor tracking tables and the replication system tables to determine current latency

Advanced Tuning: Unconventional Solutions to Everyday Problems

Q&A

Advanced Tuning: Unconventional Solutions to Everyday Problems Thank You! The PowerPoint slide-deck and the SQL code will be posted on my blog tonight: