RE: GTT Locks
- From: Ravi Kulkarni <kulkarni.ravi@xxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Wed, 03 Mar 2004 15:55:35 -0600
Thanks Jonathan..
What I am trying to understand is -
1. Why should there be a lock ONLY when using a select from a regular table and
NOT when doing a simple insert ?
2. Why is the change in functionality between 8i and 9i ?
3. Where can I get more info(papers etc.) on this since we are using GTTs
extensively and are gearing up for production in a few weeks.
Thanks,
Ravi.
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx]On Behalf Of Jonathan Lewis
Sent: Wednesday, March 03, 2004 12:04 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: Re: GTT Locks
Notes in-line
Jonathan Lewis
http://www.jlcomp.demon.co.uk
The Co-operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/faq/ind_faq.html
March 2004 Hotsos Symposium - The Burden of Proof
Dynamic Sampling - an investigation
March 2004 Charlotte OUG (www.cltoug.org) CBO Tutorial
April 2004 Iceland
June 2004 UK - Optimising Oracle Seminar
----- Original Message -----
From: "Ravi Kulkarni" <kulkarni.ravi@xxxxxxx>
To: <oracle-l@xxxxxxxxxxxxx>
Sent: Wednesday, March 03, 2004 5:15 PM
Subject: RE: GTT Locks
> John,
>
Jonathan
>
> The table GTT needs to be a Global Temporary table.
>
Absolutely true - I don't know how I managed
to forget the GT bit when I was doing the test
Having corrected the error, I agree with your observations:
insert into gtt values (1);
Locks:
TY ID1 ID2 LMODE
-- ---------- ---------- ----------
TX 131091 7538 6
TO 30494 1 3
commit;
insert into gtt select rownum from user_objects where rownum = 1;
TY ID1 ID2 LMODE
-- ---------- ---------- ----------
TX 393219 7548 6
TM 30494 0 3
TO 30494 1 3
commit;
begin
for i in 1..10000 loop
insert into gtt values (i);
end loop;
end;
/
TY ID1 ID2 LMODE
-- ---------- ---------- ----------
TX 458780 7532 6
TO 30494 1 3
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--- Ravi Kulkarni <kulkarni.ravi@xxxxxxx> wrote: > Trying to understand
the locking behavior of
GTTs (Global Temporary Tables) :
> (GTT_T is a GTT. T is a regular table)
>
> SQL> insert into gtt_t values (1000);
> 1 row created.
>
> SQL> select object_name, object_type, a.object_id, b.locked_mode from
dba_objects a,
> v$locked_object b where a.object_id=b.object_id;
> no rows selected
>
> SQL> insert into gtt_t select *from T;
> 1 row created.
>
> SQL> select object_name, object_type, a.object_id, b.locked_mode from
dba_objects a,
> v$locked_object b where a.object_id=b.object_id;
>
> OBJECT_NAME OBJECT_TYPE OBJECT_ID OBJECT_ID LOCKED_MODE
> ----------------------------------------------------------------
> GTT_T TABLE 204835 204835 3
>
>
> The user acquires a lock on the GTT for performing DML ONLY when
selecting from a Non-GTT.
> 1. How is this different from the first insert on GTT? (In either case,
noticed a 'TO'
> lock-type in v$lock)
> 2. Where can I find more info on GTT-peculiarities ?
>
> TIA,
> Ravi.
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