ODS(Operational Data Store) - This has a broad enterprise 
wide scope, but unlike the real entertprise data warehouse, 
data is refreshed in near real time and used for routine 
business activity.

snowflake schema is centrally located fact table .and 
surrounded by normalized dimension tables..
in snowflake compare to dimensions and ffact table 
dimensions are small.dimensions are more compare to ster 
chema .. snow flake shema very dificult to understand ...

there is no facts in the fact table.that table is called 
factless fact table

A fact table which is having only foreign keys.There is no
measures

A Staging area simplifies building summaries and general 
warehouse management.

datamart like a small datawarehouse..
its contains subset of datawarehouse..
data mart contains one particular subject oriented data..

Materialized views are schema objects that can be used to
summarize, precompute, replicate, and distribute data. E.g.
to construct a data warehouse.

A materialized view provides indirect access to table data
by storing the results of a query in a separate schema
object. Unlike an ordinary view, which does not take up any
storage space or contain any data.

The existence of a materialized view is transparent to SQL,
but when used for query rewrites will improve the
performance of SQL execution. An updatable materialized view
lets you insert, update, and delete.

You can define a materialized view on a base table,
partitioned table or view and you can define indexes on a
materialized view.

A materialized view can be stored in the same database as
its base table(s) or in a different database.
Materialized views stored in the same database as their base
tables can improve query performance through query rewrites.
Query rewrites are particularly useful in a data warehouse
environment.

Well, this question is not specific to Datawarehouse. In 
general these are the practises followed in software firms 
while going ahead with any new project. Lets hover around 
each topic asked

SRS (Software requirement Specification) : This is the 
initial phase where customer specifies its requirements to 
a software team. Actually its a study of what the customer 
is asking for. It captures all details of issues faced by 
customer and what are the projected solutions.

HLD (High Level Design) : This is next phase of design 
where the inputs given from SRS are collected and 
transformed into development methodolgy. It lays down the 
roadmap of code development before actually jumping onto 
the development.

LLD ( Low Level Design) : This is a actually a design 
document. It gives all code details, all issue pertaining 
to development. Its development tools, how to resolve 
issues based on the given platform, so on so forth.

Code Review : This is the final phase of development where 
developer is been rewarded for all his hard work and its 
solution. Usually Managers, Sr. Developer, Product Managers 
all sit together, get the feel of product and try to figure 
out any loopholes. If any, developers are been asked to 
revisit the code or else product is ready for QA team to 
test and certify.

Hot File:If we generate a report from two different 
database, at that time we go for Hot File.The only drawback 
is it will occupy the whole space in the hard disk.

Need of DWH:if u want enterprise reporting and analysis 
from your historical data.

Junk dimension: A junk dimension is a collection of random 
transactional codes, flags and/or text attributes that are 
unrelated to any particular dimension.  Simply to say a 
randomly used dimension is junk dimension

What shree uday said that is right and with that there is
one another thing we can say ........
i.e we can simply say which dimension is having low cardinality

A number of very small dimensions might be lumped together 
to form a single dimension, a junk dimension - the 
attributes are not closely related. Grouping of Random 
flags and text Attributes in a dimension and moving them to 
a separate sub dimension is known as junk dimension.

in bo 6.5: 1.we call web & desktop intelligence as whole as
business objects
          2. in this we use ASCII code
          3. in this  we use Clausic Universe only.
          
in BO XI R2: 1. in this we call web intelligence as web
intelligence & desk intelligence as desk intelligence
seperately.
          2.in this we use UNIQUE code
          3.in this we use Clausic Universe & OLAP Universe

Let me know about drill by please my dear friends....

Drill through  is process of converting summarized data into
detailed data.......we can say like this simplyyy

  Drill Through to Cognos Query

To set up drill through from PowerPlay Web to a Cognos Query
report, you must perform the following tasks:

    * In Cognos Query, save the query you want to drill
through to as an .iqd file.
    * In Transformer, specify the drill-through targets
(.iqd files) for your measures or PowerCubes. You must then
update all affected cubes .
    * In PowerPlay Enterprise - Server Administration,
enable drill through and specify the required URL to start
Cognos Query. 

Notes

    * When a drill through is executed, it passes the
current dimension line settings as filter parameters. If the
.iqd file cannot apply these filters, due to incorrect
column labeling, the drill through may return unexpected
results.
    * For a drill-through request to execute properly, a
copy of the .iqd file must be replicated on the target
Cognos Query server. The path must be the same relative to
the folder in which Cognos Query is installed on the target
server.
    * When performing a drill through, only the current
dimension line settings are passed as filter parameters to
the drill-through target. Unlike PowerPlay client, where the
active cell is also passed with the dimension line setting,
PowerPlay Web does not identify an active cell. 


Design Queries as Drill-through Targets

The design criteria for a drill-through query are different
from a cube creation query in the following ways:

    * Drill-through queries typically include many
non-additive text properties that you would not include in a
Transformer source query, such as Addresses and Phone
Numbers. These columns are the objective of drilling through.
    * Drill-through queries should include links to other
entities for further exploration. There is no reason to
include links in .iqd files that you intend to use only for
cube creation (not as drill-through queries).
    * Queries used as drill-through targets must be saved in
a folder that all the drill-through users have access to.
    * Queries used as drill-through targets should contain
the attributes used to define levels in the cube. Cognos
Query can only filter on attributes included in the query. 


Save a Drill-through Target in Cognos Query

PowerPlay Web requires an .iqd file to drill through to
Cognos Query. To create the .iqd file, you must enable drill
through for the report in Cognos Query and re-publish the
report to Upfront. The .iqd file will be created.
Steps

   1. In your Web browser, open or create a Cognos Query
report to which you want to drill through.
   2. On the Cognos Query toolbar, click the Design button.
   3. On the Advanced tab, click Properties.
   4. Select the Enable Drill-Through Access check box.
   5. Click the Run Query button.
   6. On the Cognos Query toolbar, click the Save As button.
   7. Follow the steps in the NewsItem wizard, and click Finish.

      The Cognos Query report reappears in your Web browser
and the .iqd file is created on the computer where the
Cognos Query server is installed. 

      Note: After you create the .iqd file, you must use
Transformer to specify the drill-through targets (.iqd
files) for your measures or PowerCubes and update the cubes
that you want to drill from . 

Notes

    * Ensure that you use Cognos Query to create your .iqd
files for drill through from PowerPlay Web to Cognos Query.
Do not use .iqd files from Impromptu. 


Enable Drill Through to Cognos Query

After you set up your .iqd drill-through targets and update
your cubes, you can enable drill through in PowerPlay
Enterprise - Server Administration.
Steps

   1. In PowerPlay Enterprise - Server Administration, click
a cube, report, or folder.
   2. From the Edit menu, click Properties, and then click
the Settings tab.
   3. In the Cognos Query box, click Enable.
   4. In the Cognos Query Server box, select the URL for the
Cognos Query gateway, such as
http://servername/cognos/cgi-bin/cqcgi.exe
   5. To test that the drill through works, click Open with
Browser on the Tools menu. Then drill through by clicking
Drill Through and selecting the target report.

Drill through to Cognos Query is now enabled.

Go through this link 
http://apsdwh.vlaanderen.be/cognos/help/html/ppwb/nl/pes_drill_through5.html

Business Object is used to create reports by creating 
Universe with the dimension tables and fact table already 
present.
Hyperion Essbase is a Tool in which we will create the 
multi dimensional Cube in which dimensions are created in 
the Essbase itself. through which reports can be generated 
with the same Essbase or with the help of reporting tool 
Hyperion Analyzer.

any yes or no like status is an example for junk dimension

It’s simply a structure that provides a convenient place to 
store the junk attributes.

un wanted data which is not useful fo report generating
purpose tht data will be placed in the particular table that
table is known as junk dimension

bridge table nothig but its a multipart key ..
bridge table maintain relation ship between fact table and 
dimension table . at the time of having multiple key 
values,that table calls bridge table