Conference iosg::all-in-1_v30

    Hi,
    
    According to a STAR's article: no. Maybe someone can reply if 3.0 is
    supporting this (I thought it should be).
    
    Sjaak.

        The DATA_FILE function makes an excellent work-around, however.
        
        You can do a DATA_FILE GET to get the record you want to copy.
        Then do DATA_FILE PUT_FIELD for each field that that you want to
        change.  Then do a DATA_FILE PUT to write the new record.  With
        DATA_FILE, you can also check OA$STATUS to see if the GET and PUT
        are successful.
        
        _Mike

    Mike,
    
    Ok, but can you WRITE COPY a record at once, providing the old and new
    key?
    
    Sjaak.

Hi,

Re: WRITE COPY with segmented keys.

The way WRITE COPY works is rather weird.  It opens the dataset for read, and
reads the required record.  This is like the first part of a WRITE CHANGE
operation, so note that if you have a multi-field (ie segmented) key you need
to specify it with %KEY.  This is because the code only allows one field for the
key; other fields are assumed to be the data you wish to change.

Once the record is read, the dataset is opened again for write access.  The code
then craftily throws away the record buffer created for this second open, and
makes the write operation point at the read operation's record.  Don't ask me
why it doesn't just do one open for 'update' in the first place...

The rest of the fields in the command are then written to the record, just like
WRITE CHANGE.  The difference is, at the end a PUT operation is performed to
create a new record (the code assumes you've changed the key!), rather than
an UPDATE.  Note for a segmented key, you may need to specify the new key using
%KEY rather than as individual fields.  Also, I think the code may ignore new
values for other fields in some circumstances...

Sorry it's a bit vague, it's a while since I looked at the code, but it should
give you a few ideas...

Scott

             
RE .2	But, I can also use the WRITE ADD function to get the same result 
    	as the DATA_FILE functions and still have OA$STATUS supported
    
    	Are there any differences between the two results? 
    	
RE .4	Thanks for the info but I can't get it to work with any 
	combination of key field specifiers in the source and target 
	records. Using %KEY or the individual fields both return 
	OA$STATUS = 0 and the data file is not updated. 
		
	
Thanks.. Liz

>RE .2	But, I can also use the WRITE ADD function to get the same result 
>    	as the DATA_FILE functions and still have OA$STATUS supported
        
        The advantage of DATA_FILE over WRITE ADD is that with WRITE ADD
        you must reenter each field.  For the DATA_FILE method, ALL-IN-1
        holds the current record in a buffer.  You update the keys fields
        in place in the buffer and then do a DATA_FILE PUT to create the
        new record.
        
        The WRITE function in V2.4 and before did not update OA$STATUS.
        Maybe this has changed in V3.0?
        
        The syntax for WRITE ADD (to effeciently get all the fields) would
        be:
        
        FOR DATA_SET WITH .%KEY == #KEYSYM DO -
          WRITE ADD KEYFLD1=#NEWKEYFLD1, KEYFLD2=#NEWKEYFLD2, -
            AFIELD1=.AFIELD1, AFIELD2=.AFIELD2, ...
        
        _Mike

    Hi,
    
    In light of the fact that 'WRITE COPY' does not seem to work for files
    with segmented keys, which of the following operations is better in
    terms of performance for copying records. I need to copy multiple
    records at a time.
    
    a. Using DATA_FILE GETs and DATA_FILE PUTs in a loop on a single open
       dsab.
    
    b. Open the same dsab twice (with different id's) and do a 
       DATA_FILE GET on the first and do a DATA_FILE MOVE and PUT to the
       second.
    
    I haven't tried either so far. Just a pre-emptive question. I have
    another realted question.
    
    If I operate using the first option (using a single open), where is the
    record pointer after the PUT. Can I do a GET_NEXT to get the next
    logical record from the previous GET or do I need to do a fresh GET?
    
    Thanks in advance.
    
    Sudarshan