Post on 18-Jan-2017
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Database Fundamental Concepts
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FC-01: Performance Analysis
DR. SUBRAMANI PARAMASIVAM (MANI)
About me
Dr. SubraMANI ParamasivamPhD., MCT, MCSE, MCITP, MCP, MCTS, MCSACEO, Principal Consultant & Trainer @ DAGEOP (UK) Email: mani@dageop.com Blog: http://dataap.org/blog
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ContentsFC-01: Performance Analysis• Monitoring Tools• Exploring STATISTICS IO output• Identifying Performance Problems with Profiler data
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FC-01: Performance Analysis
Have you done any?
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Performance Analysis• How SQL Server & Database
performs during all sorts of transactions and heavy loads?
• It is one of the important role of a Database Administrator
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Monitoring ToolsSQL Server has bunch of tools
• SQL Trace• SQL Server Profiler • Distributed Replay Utility• SQL Server Management Studio Activity Monitor• SQL Server Management Studio Graphical Show plan• Stored procedures• Database Console Commands (DBCC)• Built-in functions• Trace flags• Other tools
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SQL Trace• Information collected from instance through events.• Store the information in File or SQL Server Management objects
(SMO).• We can monitor the information about • Locks (Deadlock)• Data File Auto Grow• Objects Altered• Scan started• SQL Batch Started/Completed
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SQL Trace & Stored Procedure• Stored procedures to create traces
• sp_trace_create• sp_trace_generateevent• sp_trace_setevent• sp_trace_setfilter• sp_trace_setstatus
• Versions applicable• Prior to 2005: Extended stored procedures that began with xp_trace_... (add, set)• 2005, 2008, 2008R2, 2012: Above sp_trace_...• 2014 onwards: Use extended events
• SQL Server Profiler – to see stored trace files.• SQL Server Profiler (GUI) uses the above set of system SP’s.
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SQL Server Profiler• It is used to monitor the SQL
server instance of the database engine. • Trace data can be stored in a file
or a table.• SQL Server Profiler helps to
monitor any specific events.• Also supports auditing the
actions performed on SQL Server instances.
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SQL Server Profiler
• Find the cause of the problem in Queries• Finding and diagnosing slow-running queries.• Capturing the series of T-SQL statements that lead
to problems.• Replicate the saved trace file in a test server to
further diagnose.• Monitoring the performance of SQL Server to tune
workloads.• Correlating performance counters to diagnose
problems.
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Distributed Replay Utility
Have you used?
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Distributed Replay Utility• Assess the impact of
• future SQL server upgrades.• hardware and OS upgrades and SQL server tuning.
• Using Distributed replay, we can replay a workload.• Used mainly for
• Application compatibility testing• Performance testing • Capacity planning
• SQL Server Profiler (SSP) & Distributed Replay Utility (DRU) overlaps.• SSP allows single computer only• Resource bottleneck• SSP is less scalable solution compared to DRU
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SQL Server Management Studio Activity Monitor• Information about SQL server
processes• how the processes affects the instance• Tabbed windows with expandable and
collapsible panes: • Overview• Processes• Resource Waits• Data File I/O• Recent Expensive Queries
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Activity Monitor• Customizable• Rearrange the order of the columns• Sort any column• Filter one or more columns, • Refresh interval by default 10 seconds.
• Performance affected if <10 secs
• VIEW SERVER STATE permission required.• System objects are used.
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SSMS Graphical Show plan• SQL Server Management Studio • Interactive• GUI Tool • DBA or Developers interact with DB, SQL Server.
• Execute multiple queries simultaneously, view results, analyse the query plan.• Assists to improve the query performance.• Execution Plans• Display Estimated Execution Plan (CTRL + L) • Include Actual Execution Plan (CTRL + M)
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Graphical Show planWe can Get execution plan for all type of queries
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System Stored Procedures
Have you used?
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System Stored Procedure• SP_WHO• SP_WHO2• Custom SP_WHO2• SP_LOCK• SP_MONITOR• SP_SPACEUSED
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DBCC• DBCC means Database Console Command • Grouped into following categories• Maintenance• Miscellaneous• Informational• Validation
• During the Maintenance Plan almost every DBA will use this DBCC
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DBCC
OR
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Internal Database Snapshot
Exclusive DB Lock for Allocation checks & Catalogs&
Shared Table locks for table checks
• DBCC CHECKDB• DBCC CHECKALLOC• DBCC CHECKTABLE• DBCC CHECKCATALOG
• DBCC CHECKFILEGROUP
DBCC WITH DATABASE SNAPSHOT - Exclusions
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Snapshot not created for below conditions• Master database• Single-user mode• Read-only database• Emergency mode• Tempdb
DBCC• Some of the DBCC Commands• DBCC SQLPERF (logspace)• DBCC SHOWFILESTATS• DBCC CHECKCATALOG• DBCC CHECKCONSTRAINTS• DBCC CHECKALLOC• DBCC CHECKTABLE(tablename)• DBCC CHECKIDENT(tablename)• DBCC DBREINDEX(tablename)• DBCC INPUTBUFFER(sessionid) • DBCC SHRINKFILE(file_id)• DBCC TRACESTATUS
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Built-In Functions• Built-In functions are installed by default.• Helps getting system information.• Some of the Built-In Functions• @@io_busy – It will show I/O processing time in milliseconds• @@cpu_busy -- It will show CPU processing time in milliseconds• @@connections -- It will return no of connections/attempted connections• @@idle – It will return SQL Server idle time in milliseconds
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Trace Flags• Frequently used to diagnose performance issues• Debug stored procedures or complex computer systems.• Trace flags are valuable tools as they allow DBA to enable or disable a database
function temporarily. • Once a trace flag is turned ON, manual turn OFF or restart SQL Server.• -TXXXX can be used as startup parameter to enable trace when SS starts.• sysadmin fixed server role permission required.
For full list of Trace flags.http://technet.Microsoft.com/en-us/library/ms188396.aspx
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Other Monitoring Tools• Error Logs• Windows
• Applications• SQL Server
• Security• Setup• System
• DTA (Database Engine Tuning Advisor)
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Exploring STATISTICS IO Output• STATISTICS IO - detailed information about the impact of the Query.• Scan Counts• Logical Reads• Physical Reads• Read-ahead reads• LOB logical reads• LOB Physical reads• LOB Read-ahead reads
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Exploring STATISTICS IO output• Statistics IO can be set as an option while you execute the query.• Message displayed in results pane.• Cost of the query in terms of • physical reads from the disk and • logical reads from the cache
• KEY WORD• SET STATISTICS IO ON
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STATISTICS IO explained
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Scan Count (1) • Optimizer has chosen an execution plan.• This number will be same until you change the query.
Logical Reads (1500)• Actual number of page reads from cache.• Will not change unless there is a change in query structure or index used in
the table
STATISTICS IO explained
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• Physical Reads ( 2576) • Number of pages actually read from the disk directly.• Reads from disk first time and use the page in cache for next time.
• Read-ahead reads (0)• Total physical reads were satisfied by SQL Servers ‘Read-ahead’ mechanism. • Fluctuates, as pages are swapped in/out of memory.• Index fragmentation will affect this number.
STATISTICS IO explained
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• LOB Logical Reads (0)• Count based on text, ntext, image, varchar(max), nvarchar(max) and varbinary(max) data type.• Attention required like the Logical Reads.
• LOB Physical Reads (0)• Physical reads of same data type.
• LOB Read-Ahead Reads (0)• Number of physical reads satisfied by the Read-Ahead mechanism
Identifying Performance Problems with Profiler data
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Identifying Performance Problems with Profiler data• SQL Server Profiler helps to find the
exact problem in the database.• Performance will vary depending
on the user activity.• SSP - Highly recommend for DBA to
monitor the performance
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Identifying Performance Problems with Profiler data
• Major functions of SSP• Creating trace• Watching trace• Storing trace• Replaying trace
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ReviewMonitoring Tools
SQL TraceSQL Server Profiler Distributed Replay UtilitySQL Server Management Studio
Activity MonitorSQL Server Management Studio
Graphical Show planStored proceduresDatabase Console Commands
(DBCC)Built-in functionsTrace flags
STATISTICS IO
Performance Problems with Profiler dataCreating traceWatching traceStoring traceReplaying trace
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