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Throw exception if there are pending updates

Posted on 2011-02-28
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Last Modified: 2013-12-07
Is it possible to create and SQL block that will execute a SELECT only if there are no an uncommitted updates pending.

Ideally I would like to throw an exception if there are pending updates.  Any suggestions
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Question by:weegiraffe
5 Comments
 
LVL 28

Expert Comment

by:Naveen Kumar
ID: 34995790
you can check V$LOCKED_OBJECT or V$LOCK accordingly to check whether there are any locks on the tables ( which are being updated/deleted ).
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by:weegiraffe
ID: 34995802
hi nav_kum_v

Can you please provide a simple example of how to do this in PL/SQL block?
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Naveen Kumar earned 2000 total points
ID: 34995834
i mean just run a select statement against that view. something like this...

declare
rr_type v$locked_object%rowtype;
begin
select  * into rr_type from v$locked_object where object_id = ( select object_id from dba_objects
where object_name='MY_TEST_TABLE' ) and rownum = 1;

-- lock found
-- do something else here...may be log into error/debug table or thrown an exception/error message.

exception when no_data_found then
    -- no locks
    null;    
end;
/
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LVL 74

Expert Comment

by:sdstuber
ID: 34996429
why do you want to check for updates before issuing a select?

updates don't block select?  It's perfectly safe to do so.
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LVL 35

Expert Comment

by:johnsone
ID: 34997946
Rather than checking a V$ view, why not just do a SELECT ... FOR UPDATE NOWAIT.  That should error out if it cannot lock all the rows.

However, I do agree with sdstuber, as the locks would not block a select, why do you need to check?
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