RE: Do selects block truncates?

Ukja,

I just posted a possible explanation to the list - the truncate is considered a DDL and select would block other DDL statements to prevent the table structure from being changed during the execution.

thank you

Gene Gurevich
Oracle MySQL Operations - OMO
224-405-4079

                                                                           
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             12/21/2007 09:34                                      Subject 
             AM                        RE: Do selects block truncates?     
                                                                           
                                                                           
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>this is never a bug but is the consequence of enforcing statement-level
read consistency
>which is always guranteed by oracle.

Can you explain in more detail?
Which relationship does read consistency mechanism have with the blocking of truncate by select operation?
I don't know no concept of "select" blocking any kind of operation in Oracle.
(except some internal lightweight locks like latch or buffer lock, library cache lock/pin, blah blah blah)

-----Original Message-----
From: Kurt Franke [mailto:Kurt-Franke_at_web.de] Sent: Friday, December 21, 2007 10:35 PM To: 'oracle-l'; ukja.dion_at_gmail.com
Subject: RE: Do selects block truncates?

Hi,

...
>
> If select really blocks truncate, it's a amazing bug. :)
>

this is never a bug but is the consequence of enforcing statement-level read consistency
which is always guranteed by oracle.

the only exception from this mechanism is the complete refresh of a materialized view with
"atomic_refresh => FALSE" which then does the truncate wether or not any select is runnig
on the materialized view. active select on the materialized view will break then with
ORA-08103 regards

kf

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