|Active Topics Memberlist Calendar Search Help|
|Discussions World : TECHNOLOGIES @ DISCUSSIONSWORLD.COM : DATAWAREHOUSING / DATAMINING TECHNOLOGIES|
Topic: Data Warehousing Interview Questions and Answers
Online Status: Offline
| Topic: Data Warehousing Interview Questions and Answers
Posted: 11Sep2009 at 3:06pm
Data Warehousing Interview Questions and Answers
What's A Data warehouse
What is ODS?
1. ODS means Operational Data Store.
What is a dimension table?
A dimensional table is a collection of hierarchies and categories along which the user can drill down and drill up. it contains only the textual attributes.
What is a lookup table?
A lookUp table is the one which is used when updating a warehouse. When the lookup is placed on the target table (fact table / warehouse) based upon the primary key of the target, it just updates the table by allowing only new records or updated records based on the lookup condition.
Why should you put your data warehouse on a different system than your OLTP system?
What are Aggregate tables?
Aggregate table contains the summary of existing warehouse data which is grouped to certain levels of dimensions.Retrieving the required data from the actual table, which have millions of records will take more time and also affects the server performance.To avoid this we can aggregate the table to certain required level and can use it.This tables reduces the load in the database server and increases the performance of the query and can retrieve the result very fastly.
What is Dimensional Modelling? Why is it important ?
Dimensional Modelling is a design concept used by many data warehouse desginers to build thier datawarehouse. In this design model all the data is stored in two types of tables - Facts table and Dimension table. Fact table contains the facts/measurements of the business and the dimension table contains the context of measuremnets ie, the dimensions on which the facts are calculated.
Why is Data Modeling Important?
Data modeling is probably the most labor intensive and time consuming part of
the development process. Why bother especially if you are pressed for time? A
common response by practitioners who write on the subject is that you should no
more build a database without a model than you should build a house without
What is data mining?
Data mining is a process of extracting hidden trends within a datawarehouse. For example an insurance dataware house can be used to mine data for the most high risk people to insure in a certain geographial area.
What is ETL?
ETL stands for extraction, transformation and loading.
What does level of Granularity of a fact table signify?
What is the Difference between OLTP and OLAP?
Main Differences between OLTP and OLAP are:-
What is SCD1 , SCD2 , SCD3?
SCD Stands for Slowly changing dimensions.
Why are OLTP database designs not generally a good idea for a Data Warehouse?
Since in OLTP,tables are normalised and hence query response will be slow for end user and OLTP doesnot contain years of data and hence cannot be analysed.
What is BUS Schema?
BUS Schema is composed of a master suite of confirmed dimension and standardized definition if facts.
What are the various Reporting tools in the Market?
What is Normalization, First Normal Form, Second Normal Form , Third Normal Form?
1.Normalization is process for assigning attributes to entities–Reducesdata
redundancies–Helps eliminate data anomalies–Produces controlledredundancies to
What is Fact table?
Fact Table contains the measurements or metrics or facts of business process. If your business process is "Sales" , then a measurement of this business process such as "monthly sales number" is captured in the Fact table. Fact table also contains the foriegn keys for the dimension tables.
What are conformed dimensions?
What are the Different methods of loading Dimension tables?
What is conformed fact?
Conformed dimensions are the dimensions which can be used across multiple Data Marts in combination with multiple facts tables accordingly
What are Data Marts?
Data Marts are designed to help manager make strategic decisions about their
What is a level of Granularity of a fact table?
Level of granularity means level of detail that you put into the fact table in a data warehouse. For example: Based on design you can decide to put the sales data in each transaction. Now, level of granularity would mean what detail are you willing to put for each transactional fact. Product sales with respect to each minute or you want to aggregate it upto minute and put that data.
How are the Dimension tables designed?
Most dimension tables are designed using Normalization principles upto 2NF.
In some instances they are further normalized to 3NF.
What are non-additive facts?
Non-Additive: Non-additive facts are facts that cannot be summed up for any of the dimensions present in the fact table.
What type of Indexing mechanism do we need to use for a typical datawarehouse?
On the fact table it is best to use bitmap indexes. Dimension tables can use
bitmap and/or the other types of clustered/non-clustered, unique/non-unique
What Snow Flake Schema?
Snowflake Schema, each dimension has a primary dimension table, to which one or more additional dimensions can join. The primary dimension table is the only table that can join to the fact table.
Online Status: Offline
|Posted: 22Jul2014 at 6:41pm|
Nice Data Warehousing Interview Questions and Answers list.
Online Status: Offline
|Posted: 07Aug2014 at 11:54am|
Data Recovery software that works impressively stellar to accomplish the process of recovering lost, deleted, or inaccessible data on Windows based drives and removable media.
how to recover deleted videos from iPhone
. Recovers mission-critical files from Windows hard drive and supported external media
. 'Raw Recovery' feature to flawlessly recover files from severely corrupt media
. Recovers deleted emails in MS Outlook and Outlook Express ? Recovers files from damaged or corrupt optical media
. Support for broad range of files types, including documents, photos, and multimedia files
how to recover deleted notes on iPhone
|You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot delete your posts in this forum
You cannot edit your posts in this forum
You cannot create polls in this forum
You cannot vote in polls in this forum