Friday, November 14, 2008

Questions VIII

How many ways you create ports?
Two ways:-
1.Drag the port from another transforamtion
2.Click the add buttion on the ports tab.

How many ways you can update a relational source defintion and what are they?
Two ways:-
1. Edit the definition
2. Reimport the defintion.
What are the basic needs to join two sources in a source qualifier?
Two sources should have primary and Foreign key relation ships.
Two sources should have matching data types.

What are the different options used to configure the sequential batches?
Two options
Run the session only if previous session completes sucessfully. Always runs the session.

What are the methods for creating reusable transforamtions?
Two methods:-
1.Design it in the transformation developer.
2.Promote a standard transformation from the mapping designer.After you add a transformation to the mapping , You can promote it to the status of reusable transformation.
Once you promote a standard transformation to reusable status,You can demote it to a standard transformation at any time.
If you change the properties of a reusable transformation in mapping,You can revert it to the original reusable transformation properties by clicking the revert button.

What r the active and passive transforamtions?
Transformations can be active or passive. An active transformation can change the number of rows that pass through it, such as a Filter transformation that removes rows that do not meet the filter condition.
A passive transformation does not change the number of rows that pass through it, such as an Expression transformation that performs a calculation on data and passes all rows through the transformation.

What is tracing level and what r the types of tracing level?
Tracing level represents the amount of information that informatcia server writes in a log file.
Types of tracing level:-
Verbose init
Verbose data
Compare Data Warehousing Top-Down approach with Bottom-up approach
Top down
Bottom up

How can u work with remote database in informatica?did u work directly by using remote connections?
To work with remote datasource u need to connect it with remote connections.But it is not preferable to work with that remote source directly by using remote connections .Instead u bring that source into U r local machine where informatica server resides.If u
work directly with remote source the session performance will decreases by passing less amount of data across the network in a particular time.

Why use the lookup transformation?
To perform the following tasks:-
Get a related value. For example, if your source table includes employee ID, but you want to include the employee name in your target table to make your summary data
easier to read.
Perform a calculation. Many normalized tables include values used in a calculation, such as gross sales per invoice or sales tax, but not the calculated value (such as net
Update slowly changing dimension tables. You can use a Lookup transformation to determine whether records already exist in the target.
In certain mapping there are four targets tg1,tg2,tg3 and tg4.
tg1 has a primary key,tg2 foreign key referencing the tg1's primary key,tg3 has primary key that tg2 and tg4 refers as foreign key,tg2 has foreign key referencing primary key of tg4 ,the order in which the informatica will load the target?

2]How can I detect aggregate tranformation causing low performance?
To optimize the aggregator transformation, you can use the following options.
Use incremental aggregation
Sort the ports before you perform aggregation
Avoid using aggregator transformation after update strategy, since it might be confusing.
Explain use of update strategy transformation
To flag source records as INSERT, DELETE, UPDATE or REJECT for target database. Default flag is Insert. This is must for Incremental Data Loading.

How do you load the time dimension.
ime Dimension will generally load manually by using PL/SQL , shell scripts, proc C etc......
What are the types of data that passes between informatica server and stored procedure?
Three types of data:-
Input/Out put parameters
Return Values
Status code.

What is update strategy transformation?
This transformation is used to maintain the history data or just most recent changes in to target table.

Why sorter transformation is an active transformation?
This is type of active transformation which is responsible for sorting the data either in the ascending order or descending order according to the key specifier. the port on which the sorting takes place is called as sortkeyport properties if u select distinct eliminate duplicates
case sensitive valid for strings to sort the data null treated low null values are given least priority

How to append the records in flat file(Informatica) ? Where as in Datastage we have the options
i) overwrite the existing file
ii) Append existing file
This is not there in Informatica v 7. but heard that its included in the latest version 8.0 where u can append to a flat file. Its about to be shipping in the market.
In which condtions we can not use joiner transformation(Limitaions of joiner transformation)?
This is no longer valid in version 7.2
Now we can use a joiner even if the data is coming from the same source.
If you have four lookup tables in the workflow. How do you troubleshoot to improve performance?
There r many ways to improve the mapping which has multiple lookups.
1) we can create an index for the lookup table if we have permissions(staging area).
2) divide the lookup mapping into two (a) dedicate one for insert means: source - target,, these r new rows . only the new rows will come to mapping and the process will be fast . (b) dedicate the second one to update : source=target,, these r existing rows. only the rows which exists allready will come into the mapping.
3)we can increase the chache size of the lookup.
How many types of dimensions are available in informatica?
There r 3 types of dimensions schema
2.snowflake schema
3.glaxy schema

Where should U place the flat file to import the flat file defintion to the designer?
There is no such restrication to place the source file. In performance point of view its better to place the file in server local src folder. if you need path please check the server properties availble at workflow manager.
It doesn't mean we should not place in any other folder, if we place in server src folder by default src will be selected at time session creation.

What is difference b/w Informatica 7.1 and Abinitio
There is a lot of diffrence between informatica an Ab Initio
In Ab Initio we r using 3 parllalisim
but Informatica using 1 parllalisim
In Ab Initio no scheduling option we can scheduled manully or pl/sql script
but informatica contains 4 scheduling options
Ab Inition contains co-operating system
but informatica is not
Ramp time is very quickly in Ab Initio campare than Informatica
Ab Initio is userfriendly than Informatica

How many types of facts and what are they?
There are
Factless Facts:Facts without any measures.
Additive Facts:Fact data that can be additive/aggregative.
Non-Additive facts: Facts that are result of non-additon
Semi-Additive Facts: Only few colums data can be added.
Periodic Facts: That stores only one row per transaction that happend over a period of time.
Accumulating Fact: stores row for entire lifetime of event.

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