[Info-vax] C... the only winning move is not to play...

[David Froble]

Hein RMS van den Heuvel wrote:

> Indexed files (expect RSX PROLOGUE-1) have the primary key moved to the front of the record and may be compressed.

This is something new to me.  Can you be a  bit more specific?

I know that the order of RMS indexed records is by the primary key.

I know that the keys can be compressed.

Is the key maintained in the RMS file as an addition to the data 
record,?  What I'm asking, is the key a separate piece of data?

My understanding is that the secondary keys have as the data portion of 
the key a pointer to the actual data record, and I believe that with 
duplicate keys, there is one key and a list of associated data record 
pointers.  But, it's been a while, my memory can be faulty.

Just as a point of discussion, the DAS database product I implimented 30 
years ago treated all keys the same, the key and a pointer.  Data 
records could be anywhere, and keys could be changed without actually 
moving the data record.  A better idea, I thought, than the RMS 
requirement of deleting the old record and adding a new record if 
changing the primary key, since the data record location is dependent 
upon the primary key value.