Data Warehousing questions:
1) What is source qualifier?
Source qualified represents the rows that IS reads from relational or flatfile source when the session runs.
2) Difference between DSS & OLTP?
DSS is decision support system. It is used for analyzing data. Queries on this system access lots of rows and take time between minutes to hrs. OLTP is online transaction processing. It is used for storing operational data. Queries on this will affect few rows and time taken will be in seconds.
3) Explain grouped cross tab?
4) Hierarchy of DWH?
5) How many repositories can we create in Informatica?
I think only 1 repository can be created for 1 server
6) What is surrogate key?
Surrogate key is an artificial key created to uniquely identify rows. It is used to replace natural key. There are many reasons as to why natural keys should not be used to identify records.it is possible that data is sourced from different data marts and meaning of value of a natural in 1 data mart is different than the one from another data mart. Could be production purges its keys or reuses old keys. Also if u have to join with another system which uses different rules for natural keys.
7) What is difference between Mapplet and reusable transformation?
Mapplet is an object that represents a collection of transformations. This object is reusable. Reusable trans. Are individual transformations that are provided by Informatica.
8) What is aggregate awareness?
9) Explain reference cursor?
10)What are parallel querys and query hints?
11)DWH architecture?
12)What are cursors?
13)Advantages of de normalized data?
Denormalised data will reduce the no of joins required.
14)What is operational data source (ODS)?
It is designed for queries on transactional data. Data in ODS is updated and typical queries are on small amount of row which takes less time (in seconds)
15)What is meta data and system catalog?
16)What is factless fact table? what are semi-additive fact tables?
A factless fact table captures the many-to-many relationships between
dimensions, but contains no numeric or textual facts. They are often used to record events orcoverage information. Common examples of factless fact tables include:
- Tracking student attendance or registration events
- Identifying building, facility, and equipment schedules for a hospital or university
Semi-Additive: Semi-additive facts are facts that can be summed up for some of the dimensions in the fact table, but not the others. For example:
Current_Balance and Profit_Margin are the facts. Current_Balance is a semi-additive fact, as it makes sense to add them up for all accounts (what's the total current balance for all accounts in the bank?), but it does not make sense to add them up through time (adding up all current balances for a given account for each day of the month does not give us any useful information
17)what is confirmed dimension?
A confirmed dimension is a dimension that can be used across data marts.
18)What is the capacity of power cube?
19)Difference between PowerPlay transformer and power play reports?
20)What is IQD file?
21)What is Cognos script editor?
22)What is difference macros and prompts?
23)What is power play plug in?
24)Which kind of index is preferred in DWH?
25)What is hash partition?
26)What is DTM session?
27)How can you define a transformation? What are different types of transformations in Informatica?
Transformation is a repository object that generates, modifies or passes data. Designer provided a set of transformations that are programmed to perform some action. Transformation in a mapping means the action IS has to perform on data. Transformation can be of 2 types either active(where no of incoming rows can differ from no of outgoing rows) and passive(where no of rows remains same). Also connected and unconnected transformations.
28)What is mapplet?
A mapplet is a reusable object that represents a set of transformations. It allows you to reuse transformation logic and can contain as many transformations as necessary. Use the Mapplet Designer to create mapplets.
29)What is query panel?
30)What is a look up function? What is default transformation for the look up function?
31)What is difference between a connected look up and unconnected look up?
Connected lookup is part of dataflow. It can return any no of columns. Each row is passed through it. If no match found it can return default value. Use unconnected lookup if value required only for few rows based on some condition.
32)What is staging area?
33)What is data merging, data cleansing and sampling?
34)What is up date strategy and what are the options for update strategy?
Options for update strategy are dd_insert, dd_update, dd_delete and dd_reject
35)OLAP architecture?
36)What is subject area?
Subject areas are nothing but functional areas of an enterprise. eg. Party, Geography, etc.
37)Why do we use DSS database for OLAP tools?
DSS databases are designed for analyzing and searching for patterns. They are more suited for OLAP tools since ODS databases are designed keeping performance in mind.
Business Objects FAQ:
38)What is a universe?
39)Analysis in business objects?
40)Who launches the supervisor product in BO for first time?
41)How can you check the universe?
42)What are universe parameters?
43)Types of universes in business objects?
44)What is security domain in BO?
45)Where will you find the address of repository in BO?
46)What is broad cast agent?
47)In BO 4.1 version what is the alternative name for broadcast agent?
48)What services the broadcast agent offers on the server side?
49)How can you access your repository with different user profiles?
50)How many built-in objects are created in BO repository?
51)What are alertors in BO?
52)What are different types of saving options in web intelligence?
53)What is batch processing in BO?
54)How can you first report in BO by using broadcast agent?
55)Can we take report on Excel in BO?
Questions on Data warehousing from the mail
Please find the Data Warehousing General Interview Questions.
1What is a data-warehouse?
Data warehousing is a process where
2 Name some of them
3. Why should you put your data warehouse on a different system than
your OLTP system
5 Why are OLTP database designs not generally a good idea for a Data
Warehouse
6 Which columns go to the fact table and which columns go the
dimension table
7 What type of Indexing mechanism do we need to use for a typical
datawarehouse
8 What Snow Flake Schema
9 What is VLDB
10 What is the Difference between OLTP and OLAP
11 What is SCD1 , SCD2 , SCD3
12 What is real time data-warehousing
13 What is ODS
14 What is Normalization, First Normal Form, Second Normal Form ,
Third Normal Form
15 What is Fact table
16 What is ETL
17 What is ER Diagram
18 What is Dimensional Modelling
19 What is data mining
20 What is a Star Schema
21 What is a lookup table
22 What is a level of Granularity of a fact table
23 What is a general purpose scheduling tool
24 What is a dimension table
25 What does level of Granularity of a fact table signify
26 What are the various Reporting tools in the Market
27 What are the vaious ETL tools in the Market
28 What are the Different methods of loading Dimension tables
29 What are slowly changing dimensions
30 What are Semi-additive and factless facts and in which scenario
will you use such kinds of fact tables
31 What are non-additive facts
32 What are modeling tools available in the Market
33 What are conformed dimensions
34 What are conformed dimensions
35 What are Aggregate tables
36 What are Data Marts
37 How do you load the time dimension
38 How are the Dimension tables designed
39 Explain the advanatages of RAID 1, 1/0, and 5. What type of RAID
setup would you put your TX logs
40 Differences between star and snowflake schemas
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Around 47 Interview Questions on Data Warehouse » ETL
Only 1 message in topic - view as tree
1 What is a staging area? Do we need it? What is the purpose of a
staging area?
2 When do we Analyze the tables? How do we do it?
3 What is the difference between Power Center & Power Mart?
4 What is partitioning? What are the types of partitioning?
5 What is latest version of Power Center / Power Mart?
6 What is Informatica Metadata and where is it stored?
7 What is Full load & Incremental or Refresh load?
8 What is a three tier data warehouse?
9 What is a mapping, session, worklet, workflow, mapplet?
10 What are the various transformation available?
11 What are the various tools? - Name a few
12 What are the various methods of getting incremental records or
delta records from the source systems?
13 What are the modules in Power Mart?
14 What are the different Lookup methods used in Informatica?
15 What are snapshots? What are materialized views & where do we use
them? What is a materialized view log?
16 What are parameter files ? Where do we use them?
17 What are active transformation / Passive transformations?
18 Techniques of Error Handling - Ignore , Rejecting bad records to
a flat file , loading the records and reviewing them (default values)
19 How to determine what records to extract?
20 How do we extract SAP data Using Informatica? What is ABAP? What
are IDOCS?
21 How do we call shell scripts from informatica?
22 How can we use mapping variables in Informatica? Where do we use
them?
23 Do we need an ETL tool? When do we go for the tools in the
market?
24 Compare ETL & Manual development?
25 Can we use procedural logic inside Infromatica? If yes how , if
now how can we use external procedural logic in informatica?
26 Can we override a native sql query within Informatica? Where do
we do it? How do we do it?
27 Can Informatica load heterogeneous targets from heterogeneous
sources?
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