Re: DDL & long-running query

tim.kearsley_at_milton-keynes.gov.uk wrote:

> I don't believe this is correct. The OP mentioned a long-running
> QUERY. Surely a query holds no locks and the ALTER TABLE command would
> therefore complete without any problem?
>
> Tim Kearsley
> HBS Milton Keynes
>
> DA Morgan wrote:
>

>>John wrote:
>>
>>
>>>Hi all,
>>>
>>>I am not sure how to answer this question:
>>>"What happens if you run a DDL, say alter table, on a table

>>>being accessed by a long-running query?"
>>>
>>>Would the query fail?
>>>
>>>
>>>John
>>
>>The ALTER TABLE hangs until it can obtain the required lock.
>>--
>>Daniel A. Morgan
>>University of Washington
>>damorgan_at_x.washington.edu
>>(replace 'x' with 'u' to respond)

Please do not top post

Consider the following:

CREATE TABLE t (
colone VARCHAR2(10),
coltwo VARCHAR2(10));

INSERT 100,000,000 rows.

In session 1:
SELECT *
FROM t;

In session 2:
ALTER TABLE t
DROP COLUMN coltwo;

Do you think the column will be dropped before the SELECT completes?

Check this out too:
http://download-west.oracle.com/docs/cd/B14117_01/server.101/b10743/consist.htm#sthref2106

-- 
Daniel A. Morgan
University of Washington
damorgan_at_x.washington.edu
(replace 'x' with 'u' to respond)