Creating Dataviews for CA Datacom/DB Native Command Access › Rules for CA Datacom/DB Native Command Access › Cataloging the Dataview › Variable Length Records

Variable Length Records

All tables defined to CA Datacom/DB are considered fixed‑length records. The VSAM/Transparency feature of CA Datacom/DB can simulate variable length records. Records nominally defined to the dictionary as fixed‑length can take up different amounts of space per record if data compression is used.

CA Ideal does not support variable length fields in CA Datacom/DB dataviews nor multiple length records of different lengths.

For example, field A can be between 50 and 80 bytes.

CA Ideal supports variable repeating fixed length groups. For VSAMT dataviews, you must define the Datadictionary structure with the following rules:

1. The dataview must consist of one element that contains the entire table definition.
2. The variable occurring group must be at the end of the record. You must define the maximum number of times the group can occur (REPEAT) and identify a field for the DEPENDING ON value on the field attribute definition. There can only be one variable occurring group.
3. The user compression exit in the CXX must be DBVVRPR. This is what tells DB this is a variable length table. The Datadictionary table attribute USER COMPRESSION must be set to DBVVRPR and CA Datacom/DB COMPRESSION set to No.

This is what tells CA Ideal at catalog time that the dataview is variable length. If both the dictionary and the CXX do not contain the exit name, element length discrepancy messages probably result. For example, if CA Ideal does not catalog the dataview as variable, it expects the maximum length. DB returns the actual variable length of the entire record.

You can identify a dataview as a variable length VSAMT dataview. It displays an extra line that indicates this is a VAR OCCURRENCE RECORD for an CA Datacom/DB type dataview.

The following table displays a variable length VSAMT dataview:

>------------------------------------------------------------------------
IDEAL:  DISPLAY DATAVIEW     DVW IDEAL‑VSAMT(T001)     SYS:KTD

Seq Level Field name      T I  Ch/Dg  Occur  K Value/Redef/Dep on
=========================== T O P ================================
CATALOGED 12/05/94 17:49  DATACOM/DB UPD=YES DBID=052

                          VAR OCCURENCE RECORD
1  1    IDEAL‑VSAMT         X      4     2
2  2    SIMPLE‑REPEAT       X       4         K
3  2    KEY‑FIELD           X       3
4  2    ODO‑FIELD           U P     3
5  2    ODO‑REPEAT          X       4   14  DEP ON ODO‑FIELD
=========================== B O T T O M ==========================