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PSSDiag SQL Nexus

What does it collect? Server Configuration PerfStats Script Event Logs Performance Monitor Profiler Trace Error Logs

It’s all about the bottleneck

Look for high number of logical reads Could be heavy compiles Could be stale statistics Find the most expensive query

What can I do? Enable Optimize for Adhoc Workloads Parameterization: Forced

Look for scans, hashes, sorts or expensive operators in plan Look for high number of logical reads Could be heavy compiles Find the most expensive query Incorrect cardinality estimation a top issue Missing indexes or out of date stats May be a query design issue Parallel queries may take over the machine Common issues Tune indexes, stats, and/or query Limiting MAXDOP for parallel queries is temporary Apply a hotfix build Parameterize the query to reduce compiles Common Solutions What if I don’t have high CPU?

Is it waiting on another resource? Is it idle? Is it running? Find the lead blocker Transaction not committed or long running transaction Waiting on another resource Poor query plan Basic concurrency is “working” Common issues Tune index, stats, and/or query Application design (Ex. Fix commit tran problem) Consider READ_COMMITTED_SNAPSHOT db option Typical Solutions Deadlocks start as blocking. Almost always app problem. A large blocking chain can lead to a “hang” as seen in ERRORLOG What if I don’t have blocking?

Turtle

High Sec/T + High Bytes/Sec = SQL Flood High Sec/T + High Bytes/Sec = SQL Flood High Sec/T + Low Bytes/Sec = Disk Subsystem High Sec/T + Low Bytes/Sec = Disk Subsystem

This is starting to sound familiar…

Not enough cache for data Physical read counters Buffer Cache Hit Ratio is misleading Check ‘max server memory’ Memory throttles lead to blocking Compile memory Query memory (sorts and hash joins) Not enough cache for queries Engine has forced limits Too many ad-hoc queries Check compilations/sec

DMVs, sp_updatestats, UPDATE STATS, and “auto stats” Update Stats DMVs, SHOWPLAN, and DTA Create missing indexes Change T-SQL, Query Hints, Plan Guides Change query Tune index, stats, query Change application Often required for blocking/deadlocks Tune hardware CPU, Memory, I/O Don’t just jump to any of these!

Test 5GB No kitchen sink

Use Showplan All for queries that never complete

Only run a heavy trace for a few minutes

True or False?

PSSdiag /B 14:00:00 PSSdiag /E +02:00:00 PSSdiag /B 08:00:00 /E +09:00:00 PSSdiag /E 02:00:00 /L /Q All command line parameters:

Is it SQL Server? Running (High CPU)? Find the most expensive query Missing indexes/stats or “stale” stats? Plan look “poor”? Cardinality Estimation Problems? Waiting? Locks (Blocking) I/O Network Other Latch Other Wait It’s all about the bottleneck SQL Server Wide Configuration rarely is the cause