Title: SQL Analysis Services 2005
1SQL Analysis Services 2005
2- Microsoft SQL Server 2005 Analysis Services
provides unified, fully integrated views of your
business data to support online analytical
processing (OLAP), key performance indicator
(KPI) scorecards, and powerful data mining
capabilities. It provides reliable business
decision support solutions - SQL Server 2005 Analysis Services (SSAS) provides
- Unified and integrated view of all your business
data - Reporting, online analytical processing (OLAP)
analysis - Key Performance Indicator (KPI) scorecards
- Data mining
3Advantages
- Microsoft SQL Server 2005 Analysis Services,
organizations now have a single, consistent
solution for reporting against either OLTP or
OLAP data stores. - Reduces the amount of effort required to provide
a consistent view of data that is integrated from
an array of disparate applications and formats
4Terminologies
- Cube
- The basic unit of storage and analysis in
Analysis Services is the cube. A cube is a
collection of data thats been aggregated to
allow queries to return data quickly. - Dimension
- Each cube has one or more dimensions, each based
on one or more dimension tables. A dimension
represents a category for analyzing business data - Fact table
- A fact table contains the basic information that
you wish to summarize. This might be order detail
information, payroll records, or anything else
thats amenable to summing and averaging.
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6ARCHITECTURE
7A schema is a collection of database objects,
including tables, views, indexes, and synonyms.
- Star Schema
- A relational database schema for representing
multidimensional data. - It is the simplest form of data warehouse schema
that contains one or more dimensions and fact
tables. It is called a star schema because the
entity-relationship diagram between dimensions
and fact tables resembles a star where one fact
table is connected to multiple dimensions. - The center of the star schema consists of a large
fact table and it points towards the dimension
tables. - The advantage of star schema are slicing down,
performance increase and easy understanding of
data.
8- Snowflake schema
- A star schema structure normalized through the
use of outrigger tables. i.e dimension table
hierachies are broken into simpler tables. - In OLAP, this snow flake schema approach
increases the number of joins and poor
performance in retrieval of data. Since dimension
tables hold less space, snow flake schema
approach may be avoided.
9- Important aspects of Star Schema Snow Flake
Schema - In a star schema every dimension will have a
primary key. - In a star schema, a dimension table will not have
any parent table. - Whereas in a snow flake schema, a dimension table
will have one or more parent tables. - Hierarchies for the dimensions are stored in the
dimensional table itself in star schema. - Whereas hierarchies are broken into separate
tables in snow flake schema. These hierarchies
helps to drill down the data from topmost
hierarchies to the lowermost hierarchies.
10- OLAP world, there are mainly 3 different types
- Multidimensional OLAP (MOLAP)
- Advantages
- Excellent performance
- In MOLAP, data is stored in a multidimensional
cube. - The storage is not in the relational database,
but in proprietary formats. - MOLAP cubes are built for fast data retrieval,
and are optimal for slicing and dicing
operations. - Disadvantages
- It is limited in the amount of data it can
handle. Because all calculations are performed
when the cube is built, it is not possible to
include a large amount of data in the cube
itself. - It requires an additional investment in human and
capital resources are needed.
11- Relational OLAP (ROLAP)
- This methodology relies on manipulating the data
stored in the relational database - Advantages
- It can handle large amounts of data, ROLAP itself
places no limitation on data amount - Disadvantages
- Performance can be slow. Because each ROLAP
report is essentially a SQL query (or multiple
SQL queries) in the relational database, the
query time can be long if the underlying data
size is large . - It is difficult to perform complex calculations .
12- Hybrid OLAP (HOLAP) refers to technologies that
combine MOLAP and ROLAP. - Advantages
- For summary-type information, HOLAP leverages
cube technology for faster performance. - When detail information is needed, HOLAP can
"drill through" from the cube into the underlying
relational data.
13Advantages of SSAS Cubes
- SSAS is fast even on a large volume of data
- SSAS calculated measures are fast execution-wise
and easy reusable - They are defined centrally in the SSAS database,
and the reports pick and choose the calculated
measures they want.
14- To build a new data cube using BIDS, you need to
perform these steps - Create a new Analysis Services project
- Define a data source
- Define a data source view
- Invoke the Cube Wizard
15- To create a new Analysis Services project, follow
these steps - Select Microsoft SQL Server 2005 gt SQL Server
Business Intelligence Development Studio from the
Programs menu to launch Business Intelligence
Development Studio. -
16- To define a Data source for the new cube, follow
these steps - Right-click on the Data Sources folder in
Solution Explorer and select New Data Source.
17- To create a new data source view, follow these
steps - Right-click on the Data Source Views folder in
Solution Explorer and select New Data Source
View.
18- BIDS will automatically display the schema of the
new data source view
19- To create the new cube, follow these steps
- Right-click on the Cubes folder in Solution
Explorer and select New Cube. -
20Deploying ,Processing, Browsing a Cube
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22Aggregations Aggregation Wizard
- Pre calculated summaries of data from
- leaf levels
23Aggregations
- Aggregations provide performance improvements by
allowing Microsoft SQL Server 2005 Analysis
Services (SSAS) to retrieve pre-calculated totals
directly from cube storage instead of having to
recalculate data from an underlying data source
for each query. - The Aggregation Design Wizard uses a
sophisticated algorithm to select aggregations
for pre calculation so that other aggregations
can be quickly computed from the pre calculated
values. - This technique saves processing time and reduces
storage requirements, with minimal effect on
query response time. - After the aggregation has been created, if the
structure of a cube ever changes, or if data is
added to or changed in a cube's source tables, it
is usually necessary to review the cube's
aggregations and process the cube again.
24Aggregation Design Wizard.
- Microsoft provides a nice wizard to generate
aggregates on measure groups and partitions
25MDX
- Multidimensional Expressions (MDX) is the query
language that you use to work with and retrieve
multidimensional data in Microsoft SQL Server
2005 Analysis Services (SSAS). - MDX is superficially similar in many ways to the
SQL syntax that is typically used with relational
databases. However, MDX is not an extension of
the SQL language and is different from SQL in
many ways. - Basic MDX Select Query
26Calculations
- Calculated members are customized measures or
dimension members that are defined based on a
combination of cube data, arithmetic operators,
numbers, and functions. For example, you can
create a calculated member that calculates the
sum of two physical measures in the cube.
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30 SSAS 2005 Day 2
31KPIs
- KPIs or Key Performance Indicators are one of the
most important entities in driving business
decisions. It can be defined as a (quantifiable)
measurement used to define and measure an
organization's progress in achieving business
goals. - SQL Server 2005 Analysis Services, allows for the
creation of KPIs on its cubes. - KPI measure the health of a business.
- KPI uses graphic displays to display status and
trend eg. Traffic light - KPI defines 4 expressions for performance metrics
- Actual Value (-1 to 1)
- Goal Value
- Status (-1 to 1)
- Trend (-1 to 1)
32KPI Terms used in SSAS
- Value
- The value is an MDX expression used to return the
actual value of the KPI - Goal
- The goal is an MDX expression used to specify the
target value of the KPI. - Status
- Ideal values for the status would be a max of 1
(good) to a minimum of -1 (bad), while 0
indicates neutral status - Status Indicator
- The status indicator is a visual element which is
used to present the status of the KPI. Eg gauges,
traffic lights or smileys. - Trend
- The trend is an MDX expression that evaluates the
value of a KPI across time. It can be expressed
using any time based criteria. Using this, the
business user will be able to determine how the
KPI's value has progressed over time. - Trend Indicator
- The trend indicator is a visual element which is
used to present the trend of the KPI.
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35The KPIs are done! Next, process the cube. You
will be able to view the KPIs using the built-in
KPI Browser under the KPIs tab in BIDS.
36Actions
- Cube supports actions and action taken in basis
of data - URL Go to a specified URL. This type of action
supports both directing the user to some URL to
obtain further information, and directing the
user to some Web-based application that allows a
new task to be performed. - For exampleFor a product, go to the company
website describing that product. - Reporting
- Execute a specified report. For eg for a given
product code the action could execute a
parameterized report providing description and
current order status - Drill through
- User can drill through to the lowest level of
detail.
37Actions- Drillthrough
38- The most important aspect of it is that drill
through returns detail level data from within the
cube. - The target can be a cube, dimension, hierarchy,
level, dimension members, hierarchy members,
level members, set, cells, etc. An action that
targets cells can be further restricted to a
subspace of the cube using an MDX expression.
39Partitions
- A database partition is an independent subset of
a database that contains its own data, indexes,
configuration files, and transaction logs. - A partition group is a logical grouping of one or
more database partitions that lets you control
the placement of table spaces and buffer pools
within the database partitions.
40Partitions
41Security
- Cube provide role based security. Roles can be
defined and permissions can be granted to the
role. - Administrative permissions can be granted
independently of data access permissions. Also,
separate permissions can be defined for reading
the metadata of the object, and for read/write
access to the data. - Data can be secured at levels of granularity down
to individual cells.
42Role based Security
43Security
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45Perspectives
- Users engaged on a particular task generally do
not have to see the complete model. To avoid
overwhelming users with the sheer size of the
model, we need the ability to define a view that
shows a subset of the model - The cube provides such views, called
perspectives. A cube can have many perspectives,
each one presenting only a specific subset of the
model (measures, dimensions, attributes, and so
on) that is relevant to a particular group of
users. Each perspective can then be associated
with the user security roles that define the
users who are permitted to see that perspective.
46Translations
- International users frequently have a need to
view metadata in their local language. To address
this, the cube allows translations of metadata to
be provided in any language. A client application
that connects using a particular locale would
receive all metadata in the appropriate language.
- The model can also provide translations of data.
An attribute can map to different elements in the
data source, and provide the translations for
those elements in different languages.
47- From a client computer that has a French locale,
both the cube and the query results would be
displayed in French