Tuning SSAS Processing Performance

Pragmatic Works

Tuning SSAS Processing Performance

MAKING BUSINESS INTELLIGENT www.pragmaticworks.com

Agenda

Processing Overview

Tuning Process

Bottlenecks Bandages

Surgery


About Me

John Welch, SQL Server MVP, SSAS Maestro 2008 Coauthor on

SQL Server MVP Deep Dives Smart Business Intelligence Solutions with Microsoft SQL

Server 2008

Working with SQL Server since 1996 My Contact Info

http://agilebi.com/jwelch Twitter: @john_welch Email: [email protected]


Dimension Processing

Build Attribute Stores

Build Hierarchy Stores

Build Decoding Stores

Build Bitmask Indexes


Attribute Processing

Customer

City

Region

Country

GenderIncome


Hierarchy Processing

Hierarchy stores accelerate access to dimension hierarchy members

Hierarchies process in parallel

Ordering members in the hierarchy can be time consuming Disable ordering by setting

AttributeHierarchyOrdered = FALSE


Decoding Stores

Decoding tables enable lookup of IDs for high level members by the ID for a lower level member

Unlikely to present performance bottlenecks


Build Bitmask Indexes

Bitmask indexes help look up related attributes

Depends on Decoding Stores

Loads decoding stores for related attributes into memory AttributeHierarchyOptimizedState =

NotOptimized disables the index


Partition Processing

Process Fact Data

Build Aggregations &

Indexes

ProcessData ProcessIndexes


Process Data

Read Data

Reads from database

Process Data

Maps data to Dim IDs

Aggregates data

Write Data

Sorts data

Compresses and writes data


Process Indexes

Creates indexes and aggregations

Loads decoding stores for all attributes related to granularity attributes Except for attributes that are NotOptimized

Aggregations for large partitions can spill to disk Avoid where possible


SMART Tuning Steps

Set Goals

Measure

Assess Bottlenecks

Remove Bottleneck

Test and Evaluate


Performance Monitor

MSOLAP: Processing Rows read/sec Rows written/sec

MSOLAP: Proc Aggregations Temp File Bytes Writes/sec Rows created/Sec Current Partitions

MSOLAP: Threads Processing pool idle threads Processing pool job queue length Processing pool busy threads

MSOLAP: Memory Memory Limit High KB Memory Limit Low KB Memory Usage KB

MSSQL: Memory Manager Total Server Memory Target Server Memory

Process % Processor Time msmdsrv.exe

and sqlservr.exe

Logical Disk: Avg. Disk Read Queue Length Avg. Disk Write Queue Length Avg. Disk sec/Read Avg. Disk sec/Write Disk Transfers/sec

Processor: % Processor Time Total


SQL Profiler

SQL

Performance/ Showplan XML Statistics

Profile

TSQL/ SQL:BatchCompleted

Analysis Services

Command Events

Command Begin

Command End

Progress Reports

Progress Report Begin

Progress Report End

Progress Report Error


Tuning

Run Processing in 3 steps Dimension processing

Partition ProcessData

Partition ProcessIndexes

Use the most appropriate processing type

Machine is maxed when CPU utilization = 100% Improvements past that require new hardware


Warning!

Change one thing at a time!

Most of these items involve tradeoffs

Need to understand impact of each setting


Dimension Processing Bottlenecks

Data retrieval Bandage: Add Indexes Surgery: Use SQL views to support dimensions

Processing attributes Reduce the number of attributes Add attribute relationships AttributeHierarchyOptimizedState = Not Optimized

for attributes related to key with high cardinality Use Member Properties

AttributeHierarchyEnabled = False


Partition ProcessData Bottlenecks

Data Retrieval Bandages

Add Indexes Use Compression Add lock hints (TABLOCK) Add database connections

Surgery Align relational and analytical partitions 1:1 Update data types Evaluate database server I/O and network


Partition ProcessData Bottlenecks

CPU underutilized

Bandages Processing pool job queue length > 0

If Processing pool idle threads = 0, increase Threadpool\Process\MaxThreads

If Processing pool idle threads > 0, decrease CoordinatorExecutionMode

Surgery Increase the number of partitions


Partiton ProcessIndexes Bottlenecks

Not enough memory (Temp File Bytes Writes/sec > 0)

Bandages Reduce memory usage

Decrease parallelism

Make sure TempDir is pointed to a fast disk

Surgery Add physical memory


Partiton ProcessIndexes Bottlenecks

CPU underutilized Bandages

If Processing pool idle threads = 0, increase Threadpool\Process\MaxThreads

If Processing pool idle threads > 0, decrease CoordinatorExecutionMode

Increase OLAP\Process\AggregationMemoryLimitMin

Surgery Increase partitions


I/O

Disk Queue Lengths, Avg. Reads and Writes are high

No bandages here (other than reducing disk contention)

Surgery: More / faster spindles

Short-stroke the disks

Go solid-state


Wrap Up

Tuning takes time

Set clear goals initially and revisit them

Change one thing at a time

Document along the way


Resources

Analysis Services Performance Guide

http://www.microsoft.com/downloads/en/details.aspx?FamilyID=3be0488d-e7aa-4078-a050-ae39912d2e43&DisplayLang=en

SQLCAT http://sqlcat.com

My Blog http://agilebi.com/jwelch

Twitter: @john_welch

Date post:	27-Sep-2015
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Tuning SSAS Processing Performance

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