Home Page for the TeradataForum
 

Archives of the TeradataForum

Message Posted: Mon, 13 Jun 2011 @ 07:21:05 GMT


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


Subj:   Pseudo table and deadlock for BATCHUSER
 
From:   Anomy Anom

<-- Anonymously Posted: Monday, June 13, 2011 02:41 -->

Hi Teradata Experts,

Recently, I was reading Teradata manuals to get more info about pseudo tables.

The information I could gather is: Since Teradata distributes a table across all amps, it is possible (without the pseudo table mechanism employed) that one process would grab a lock on a table on one amp and a different process grabs a lock on the same table on a different amp. They would both be trying to grab a full lock and neither could get it because the other holds out a lock that is needed. Therefore, in order to avoid this deadlock situation, one amp effectively serves as the starting amp (see the physical implementation class or the Teradata manuals for information on how) for all locks on the table and this is called a "Pseudo Table lock". Like a semaphore, it prevents deadlock on the locking of a table. Once a process has a pseudo lock, it can lock the table on all amps.

For BATCHUSER of my current project: When I try to submit insert statement from two different sessions, it results in DEADLOCK.

My question is: Why pseudo table mechanism was bypassed in case of BATCHUSER? And what could be the difference (in case of BATCHUSER v/s normal developer user) in terms of user attributes.

Thanks in advance for all your help.



     
  <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