Performance Tuning - Aggregates

8/8/2019 Performance Tuning - Aggregates

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SAP America Know How Conference Call Jujy 6, 2000 1

BW Performance Tuning:

Aggregates

Deborah BoardBW RIG USA

Know How Conference Call

July 6, 2000


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Agenda

Introduction

Definition of Aggregates

Creating Aggregates

Finding Effective Aggregates

Analyzing Queries


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Agenda

Introduction

Definition of Aggregates

Creating Aggregates


Analyzing Queries


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BW Performance Issues

Indexes

BW Statistics

AggregatesDB Statistics

Data Modeling

Partitioning

DB Tuning

Query Optimization

BWDatabase


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Agenda

Introduction

Definition of an Aggregate

Creating Aggregates


Analyzing Queries


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An InfoCube's Star Schema

(1) Fact Table

(2) Dimensions

(3) Characteristic

month

year

day

city regioncountry

productproductgroup

sales person

division

distribution channel

sales organizationTimeD

imen

sion

Product Dimension

Region Dimension

Sales

OrgDimens

ion


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A Typical Query

(1) Fact Table

(2) Dimensions

(3) Characteristic

month

region

productgroup

country = 'US' or 'CA'

year = 1999relevant facts



A Suitable Aggregate

(1) Fact Table

(2) Dimensions

(3) Characteristic

month

year

regioncountry

productproductgroup

TimeD

imen

sion

Product Dimension

Region Dimension



Aggregates ...

... are like InfoCubes,

... summarize ("aggregate") data of the originating InfoCube,

... contain redundant information, but

... accelerate the access to that information,

... are for InfoCubes what DB indexes are for DB tables,

... are performance-enhancing features.



Aggregates - Goal

Reduced retrieval

Cost

Cost of aggregate

maintenance

The goal of aggregates is to balance



Agenda

Introduction


Creating Aggregates


Analyzing Queries



Aggregates - Examples

Defining Aggregates

*

HF

space

group according to characteristic or attribute value

group according to nodes of a hierarchy level

filter according to fixed value

do not use characteristic or attribute in aggregate


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Aggregates - Example

Country Customer Sales

USA

GermanyUSA

Austria

Austria

Germany

USA

Buggy Soft Inc.

Ocean NetworksFunny Duds Inc.

Ocean Networks

Thor Industries

Funny Duds Inc.

Buggy Soft Inc.

10

155

10

10

20

25

Fact Table: Sales DataFact Table: Sales Data Aggregate Tables: Sales DataAggregate Tables: Sales Data

Country *

Customer Space

Country *

Customer Space

Country Sales

40

35

20

USA

Germany

Austria


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Aggregates - Example Using Filters


USA

GermanyUSA

Austria

Austria

Germany

USA

Buggy Soft Inc.


Ocean Networks

Thor Industries

Funny Duds Inc.

Buggy Soft Inc.

10

155

10

10

20

25


Country F, Germany

Customer *

Country F, Germany

Customer *

Country Sales

15

20

Germany

Germany

Customer

Ocean Networks

Funny Duds Inc.


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Aggregates - Example Using Master Data


USA

GermanyUSA

Austria

Austria

Germany

USA

Buggy Soft Inc.


Ocean Networks

Thor Industries

Funny Duds Inc.

Buggy Soft Inc.

10

155

10

10

20

25


Country Space

Industry *

Country Space

Industry *

Industry Sales

60

25

10

Technology

Consumer Products

Chemical

Technology

Consumer Products

Technology

Chemical

IndustryCustomer

Buggy Soft Inc.

Funny Duds Inc.

Ocean Networks

Thor Industries

Master Data Table: CustomerMaster Data Table: Customer


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Aggregates - Example Using Hierarchies


USA

Germany

USAAustria

Austria

Germany

USA

Buggy Soft Inc.

Ocean Networks

Funny Duds Inc.Ocean Networks

Thor Industries

Funny Duds Inc.

Buggy Soft Inc.

10

15

510

10

20

25


Country H, Level 2

Customer Space

Country H, Level 2

Customer Space

Country Sales

40

55

America

Europe

AllAll

EuropeEurope AmericaAmerica

GermanyGermany AustriaAustria USAUSA

Hierarchy for CountryHierarchy for Country


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Aggregates - Facts in SAP BW

on navigational attributes of time-

dependent master data

on hierarchy levels where the

structure is time-dependent

for non BasicCubes

Aggregatescan be created

Aggregates

can be createdAggregatescannot be created

Aggregates

cannot be created

on dimension characteristics

on navigational attributes

on hierarchy levels


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Aggregates - Maintenance of

Switch

on/off

Switch

on/off

Show aggregate

hierarchy

Show aggregate

hierarchy

BDSBDS

TransportTransportActivate &

Fill

Activate &

Fill

unsaved

changes

unsaved

changes

Valuation of

the aggregate

Valuation of

the aggregate


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Aggregates - Hierarchy of


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Agenda

Introduction


Creating Aggregates


Analyzing Queries


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Aggregates - Proposals

Suggest useful

aggregates

Suggest useful

aggregates

Optimize

proposals

Optimize

proposals


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Gather information about end-user

query requirements and drill-down

patterns

Aggregates are suggested basedon query design

Execute the query multiple times

using realistic drill-down scenarios

Allow time for users to execute

queries and collect SAP BW-

Statistics

Aggregates can be suggestedbased on SAP BW-Statistics

Analyze the use of aggregates

Modify aggregates for optimization

Before aggregate creationBefore aggregate creation After aggregate creationAfter aggregate creation


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Aggregates - Rules for Efficiency

Define the aggregate on the required level of detail and

afterwards add all characteristics which can be derived from thecomponent of the aggregate (business logic).

For example, if 0Calmonth is a component of the aggregate, you

should add 0Calquarter and 0Calyear as well.

You should also add 0Fiscper if the Fiscal periods correspond

to the month

Avoid placing the characteristic and its navigational attributes

in the same aggregate

Avoid aggregates which are as large as the InfoCube itself


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Aggregates - Size

Size of aggregate: 5 to 10% of

the fact table may be acceptable

For frequent changes to master data

or hierarchy structures: size of

aggregate < 1% of the InfoCube /

Basis aggregate

For infrequent changes: larger sizes

are OK

Aggregates w/ Navigational

Attributes or Hierarchies

Aggregates w/ Navigational


Aggregates w/o Navigational


Aggregates w/o Navigational



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Agenda

Introduction


Creating Aggregates


Analyzing Queries

Q A l


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Query - Analyze

Query-Analyzing Tools:

Query monitor (Transaction RSRT > execute & debug)

Trace-Tool (Transaction RSRTRACE > all logs >

double click on the protocol of interest > DB debugging)

Q A l


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Query - Analyze

Q SAP BW St ti ti


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Query - SAP BW Statistics

Meaning of the most important fields of the SAP BW Statistic

- QDBSEL: Number of selected Records on the DB- QDBTRANS: Number of Records transferred to the server

- QTIMEDB: Time in Seconds on the DB

all fields are explained in detail in OSS note 130696

If the quotient of QDBSEL divided by QDBTRANS is greater

than 10 and if the QTIMEDB is too high, you should thinkabout an aggregate

Switch on/off certain aggregates to see whether they are

efficient or not

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Performance Tuning - Aggregates

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