Home Page for the TeradataForum
 

Archives of the TeradataForum

Message Posted: Sat, 17 Jul 1999 @ 18:07:32 GMT


     
  <Prev Next>   <<First <Prev Next> Last>>  


Subj:   Re: MLOAD DELETE problem
 
From:   Eric J. Kohut

There are two methods for deleting data using Mload.

- The first method is to use the Mload Delete DML approach to read in rows from a file And load these rows into a work table similar to how Mload normally works for Other DML types of work like inserts and updates. This work table is then merged With the target tables just like any other DML operation works. While I have never tried This approach, I believe it should work. I also believe this is the approach referred to when The restriction is listed for OR'd conditions.

- If the manual states that OR'd conditions are not permitted with DML then I would advise that you Don't take this approach and conform to the manuals recommendations. Also, unless you are Reading data in from a file, you do not need to use the Mload DML approach. As I read your original e-mail this is not the approach you are using. I don't know whether the warning applies only to the DML delete approach or if it applies to the approach I'll talk about next.

- The second method is to use the specialized Mload Delete task approach to simply delete data Based upon an SQL statement. This approach still processes the data one block at a time and As a result Is optimized for this type of delete. From your comments, this is the approach that you Are using. As a result, you cannot use a DML statement or multiple for you delete task.

The reason for using Mload is that for both operations your delete would be optimized by attempting To I/O's by only touching the data blocks once for any operations. Mload also does not journal every row Like a BTEQ submitted SQL statement would prior to V2 R3. If have a V2 R3 system, you might be able to use The newly optimized SQL delete approach as an alternative to the Mload delete task. The new SQL delete approach Only journals every block and has dramatically speed up regular SQL delete processes.

Have you contacted the Global Support Center to understand whether this problem has ever been reported before?

I would advise starting here. I would guess that there is a problem with your MVS software installation, MVS interface (TDP, channel, ESCON), MLOAD delete script, or you have found a strange Mload bug since many customers use this approach to maintain their tables.


Thanks,

Eric Kohut
NCR Senior Teradata Consultant



     
  <Prev Next>   <<First <Prev Next> Last>>  
 
 
 
 
 
 
 
 
  
  Top Home Privacy Feedback  
 
 
Copyright for the TeradataForum (TDATA-L), Manta BlueSky    
Copyright 2016 - All Rights Reserved    
Last Modified: 27 Dec 2016