Informatica Interview Queston Part-6 - ETL- iNFORMATICA DEVELOPER

Tuesday, June 18, 2019

Informatica Interview Queston Part-6


ktnewslive

Q. What is the default data driven operation in informatica?

This is default option for update strategy transformation.
The integration service follows instructions coded in update strategy within session mapping determine how to flag records for insert,delete,update,reject. If you do not data driven option setting, the integration service ignores update strategy transformations in the mapping.


Q. What is threshold error in informatica?

When the target is used by the update strategy DD_REJECT,DD_UPDATE and some limited count, then if it the number of rejected records exceed the count then the
session ends with failed status.  This error is called Threshold Error.


Q. SO many times i saw "$PM parser error ". What is meant by PM?

PM: POWER MART
1) Parsing error will come for the input parameter to the lookup.
2) Informatica is not able to resolve the input parameter CLASS for your lookup.
3) Check the Port CLASS exists as either input port or a variable port in your expression.
4) Check data type of CLASS and the data type of input parameter for your lookup.


Q. What is a candidate key?


A candidate key is a combination of attributes that can be uniquely used to identify a database record without any extraneous data (unique). Each table may have one or more candidate keys. One of these candidate keys is selected as the table primary key else are called Alternate Key.


Q. What is the difference between Bitmap and Btree index?

Bitmap index is used for repeating values.
ex: Gender: male/female
    Account status:Active/Inactive
Btree index is used for unique values.
ex: empid.


Q. What is ThroughPut in Informatica?

Thoughtput is the rate at which power centre server read the rows in bytes from source or writes the rows in bytes into the target per second.

You can find this option in workflow monitor. Right click on session choose properties and Source/Target Statictics tab you can find thoughtput details for each instance of source and target.


Q. What are set operators in Oracle


UNION
UNION ALL
MINUS
INTERSECT


Q. How i can Schedule the Informatica job in "Unix Cron scheduling tool"?


Crontab
The crontab (cron derives from chronos, Greek for time; tab stands for table) command, found in Unix and Unix-like operating systems, is used to schedule commands to be executed periodically. To see what crontabs are currently running on your system, you can open a terminal and run:
sudo crontab -l
To edit the list of cronjobs you can run:
sudo crontab -e
This will open a the default editor (could be vi or pico, if you want you can change the default editor) to let us manipulate the crontab. If you save and exit the editor, all your cronjobs are saved into crontab. Cronjobs are written in the following format:
* * * * * /bin/execute/this/script.sh
Scheduling explained
As you can see there are 5 stars. The stars represent different date parts in the following order:
1.         minute (from 0 to 59)
2.         hour (from 0 to 23)
3.         day of month (from 1 to 31)
4.         month (from 1 to 12)
5.         day of week (from 0 to 6) (0=Sunday)
Execute every minute
If you leave the star, or asterisk, it means every. Maybe
that's a bit unclear. Let's use the the previous example
again:
* * * * * /bin/execute/this/script.sh
They are all still asterisks! So this means
execute /bin/execute/this/script.sh:
1.         every minute
2.         of every hour
3.         of every day of the month
4.         of every month
5.         and every day in the week.
In short: This script is being executed every minute.
Without exception.
Execute every Friday 1AM
So if we want to schedule the script to run at 1AM every
Friday, we would need the following cronjob:
0 1 * * 5 /bin/execute/this/script.sh
Get it? The script is now being executed when the system
clock hits:
1.         minute: 0
2.         of hour: 1
3.         of day of month: * (every day of month)
4.         of month: * (every month)
5.         and weekday: 5 (=Friday)
Execute on weekdays 1AM
So if we want to schedule the script to run at 1AM every Friday, we would need the following cronjob:
0 1 * * 1-5 /bin/execute/this/script.sh
Get it? The script is now being executed when the system
clock hits:
1.         minute: 0
2.         of hour: 1
3.         of day of month: * (every day of month)
4.         of month: * (every month)
5.         and weekday: 1-5 (=Monday til Friday)
Execute 10 past after every hour on the 1st of every month
Here's another one, just for practicing
10 * 1 * * /bin/execute/this/script.sh
Fair enough, it takes some getting used to, but it offers great flexibility.





Q. Can anyone tell me the difference between persistence and dynamic caches? On which conditions we are using these caches?

Dynamic:--
1)When you use a dynamic cache, the Informatica Server updates the lookup cache as it passes rows to the target.
2)In Dynamic, we can update catch will New data also.
3) Dynamic cache, Not Reusable
(when we need Updated cache data, That only we need Dynamic Cache)

Persistent:--
1)a Lookup transformation to use a non-persistent or persistent cache. The PowerCenter Server saves or deletes lookup cache files after a successful session based on the Lookup Cache Persistent property.
2) Persistent, we are not able to update the catch with New data.
3) Persistent catch is Reusable.

(When we need Previous Cache data, That only we need Persistent Cache)
----------------------------------
few more additions to the above answer.....
1. Dynamic lookup allows modifying cache where as Persistent lookup does not allow us to modify cache.
2. Dynamic lookup use 'newlookup row', a default port in the cache but persistent does use any default ports in cache.
3.As session completes dynamic cache removed but the persistent cache saved in informatica power centre server.


Q. How to obtain performance data for individual transformations?

There is a property at session level “Collect Performance Data“, you can select that property. It gives you performance details for all the transformations.

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