Defining Descriptor

, , ,
1

Hi All,

I have 2 questions about Descriptor:

  1. If I am using some descriptor in a program, Is it necessary to define that descriptor inside define data? If no what is the reason?

  2. I am reading a file for example employee file using 2 descriptors department and employee id. so internally how many inverted lists will be created?

Thanks,
Rohan.

2

No, because the DDM is doing that for you.

You are using two inverted lists then.

3

If you are using the THRU clause (or the equivalent ENDING AT) of the READ statement, then you will need to define the descriptor within the view in your program.

4

If you are using the THRU clause (or the equivalent ENDING AT) of the READ statement, then you will need to define the descriptor within the view in your program.

5

Maybe I misunderstood your question…
First of all: An inverted list has to deal with the descriptor itself. It is created during the creation of a descriptor - not during a find command. Maybe “list of ISNs” would be the correct term in your question.

If you talking about Natural’s FIND-command with 2 descriptions, you will get one list of ISNs from Adabas. Internally, Adabas creates 2 ISN-lists and merges these lists.

In fact a Natural-FIND is a combination of several ADABAS-Commands (S1-S8). For more information please see the Adabas-documentation:

http://techcommunity.softwareag.com/ecosystem/documentation/adabas/ada813mfr/adamf/comref/commands.htm#commands