Indexed file structure 
Author Message
 Indexed file structure

Hi, All!

Does anyone know if it is possible to get MF COBOL indexed file
structure if you have only the file itself and no source code of the
program it is used by?

Vitaly Khozainov



Sat, 13 Nov 1999 03:00:00 GMT  
 Indexed file structure

With the Rebuild command you can get the record size and index structure.

Rebuild indxfile.nam /I /N


Quote:
> Hi, All!

> Does anyone know if it is possible to get MF COBOL indexed file
> structure if you have only the file itself and no source code of the
> program it is used by?

> Vitaly Khozainov



Sat, 13 Nov 1999 03:00:00 GMT  
 Indexed file structure


Quote:

> Does anyone know if it is possible to get MF COBOL indexed file
> structure if you have only the file itself and no source code of the
> program it is used by?

I did write a program (in C as it happens) that will extract
details from a MF Level II .IDX file and report the keys,
record size and various other details.  It would even read
down the data file and report the deleted record count.

I never got around to updating it for Cobol/2 format, but won't
REBUILD report on these ?



Sat, 13 Nov 1999 03:00:00 GMT  
 Indexed file structure



Quote:
>Hi, All!

>Does anyone know if it is possible to get MF COBOL indexed file
>structure if you have only the file itself and no source code of the
>program it is used by?

>Vitaly Khozainov

Vitaly,

You could use the Microfocus Data File Editor that comes with
workbench or Workbench File Loader. These utilities should give you
some idea of the file structure.

Alternatively the Operating Guide manual documents the File Structure
so with this info and a good Hex editor you should be able to work out
the structure (but it would take you a while).

Cheers
Dave.



Sat, 13 Nov 1999 03:00:00 GMT  
 Indexed file structure


Thanks, but I need all the structure to be able to configure ODBC
interface for the indexed file.

Quote:
>With the Rebuild command you can get the record size and index structure.

>Rebuild indxfile.nam /I /N


>> Hi, All!

>> Does anyone know if it is possible to get MF COBOL indexed file
>> structure if you have only the file itself and no source code of the
>> program it is used by?

>> Vitaly Khozainov



Tue, 16 Nov 1999 03:00:00 GMT  
 Indexed file structure



Quote:

> Thanks, but I need all the structure to be able to configure ODBC
> interface for the indexed file.

> >With the Rebuild command you can get the record size and index
structure.

> >Rebuild indxfile.nam /I /N

Without source code you are stuck.  There is nothing in the file that
identifies data field boundaries.


Tue, 16 Nov 1999 03:00:00 GMT  
 Indexed file structure


Quote:



>> Thanks, but I need all the structure to be able to configure ODBC
>> interface for the indexed file.
>>> With the Rebuild command you can get the record size
>>> and index structure.
>>> Rebuild indxfile.nam /I /N
> Without source code you are stuck.
> There is nothing in the file that identifies data field boundaries.

Except the data field boundaries themselves! Detective work helps.

With a reasonably large data file of fixed length records you can
see the repeated patterns and hence work out the record length.

The remaining unknown is the file offset of the first record,
because of the system data often stored at the start of the file.  
To work this out, pick a particularly obvious data field (eg a
surname) and look at the *last* record.  This gives the position
of the data field in each record; now apply that to the first
record to find the start of the first record.

The key structure can be guessed by looking at the binary system
data, which probably includes (start,length) key definition pairs.

Of course, it is much simpler if you know which compiler was used
in the first place and if you can write experimental programs and
construct some sample indexed data files for comparison.

--

Mine of Information Ltd, PO BOX 1000, St Albans AL3 5NY, GB
* Independent Computer Consultancy    Established in 1977 *



Wed, 17 Nov 1999 03:00:00 GMT  
 
 [ 7 post ] 

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