Datastage Interview Questions and Answers Part-3
21) Define APT_CONFIG in Datastage?
It is the environment variable that is used to identify the *.apt file in Datastage. It is also used to store the node information, disk storage information and scratch information.
22) Name the different types of Lookups in Datastage?
There are two types of Lookups in Datastage i.e. Normal lkp and Sparse lkp. In Normal lkp, the data is saved in the memory first and then the lookup is performed. In Sparse lkp, the data is directly saved in the database. Therefore, the Sparse lkp is faster than the Normal lkp.
23) How a server job can be converted to a parallel job?
We can convert a server job in to a parallel job by using IPC stage and Link Collector.
24) Define Repository tables in Datastage?
In Datastage, the Repository is another name for a data warehouse. It can be centralized as well as distributed.
25) Define OConv () and IConv () functions in Datastage?
In Datastage, OConv () and IConv() functions are used to convert formats from one format to another i.e. conversions of roman numbers, time, date, radix, numeral ASCII etc. IConv () is basically used to convert formats for system to understand. While, OConv () is used to convert formats for users to understand.
26) Explain Usage Analysis in Datastage?
In Datastage, Usage Analysis is performed within few clicks. Launch Datastage Manager and right click the job. Then, select Usage Analysis and that’s it.
27) How do you find the number of rows in a sequential file?
To find rows in sequential file, we can use the System variable @INROWNUM.
28) Differentiate between Hash file and Sequential file?
The only difference between the Hash file and Sequential file is that the Hash file saves data on hash algorithm and on a hash key value, while sequential file doesn’t have any key value to save the data. Basis on this hash key feature, searching in Hash file is faster than in sequential file.
29) How to clean the Datastage repository?
We can clean the Datastage repository by using the Clean Up Resources functionality in the Datastage Manager.
30) How a routine is called in Datastage job?
In Datastage, routines are of two types i.e. Before Sub Routines and After Sub Routines. We can call a routine from the transformer stage in Datastage.