When creating a table in Oracle, the Parallel and Degree properties can be specified.
When creating a table and selecting * from all_all_tables, there is an INSTANCES item. Can this item be edited by the user using DDL statements such as CREATE TABLE? If there is, please ask for an example phrase.
Below is an example of setting and altering the INSTANCES property of a table:
SQL> create table test1(a number) parallel (instances 2);
Table created.
SQL> select instances from user_tables where table_name = 'TEST1';
INSTANCES
----------------------------------------
2
SQL> alter table test1 parallel (instances 1);
Table altered.
SQL> select instances from user_tables where table_name = 'TEST1';
INSTANCES
----------------------------------------
1
The table property is defined in the 19c reference as "Number of instances across which the table is to be scanned, or DEFAULT".
I think INSTANCES has been deprecated and replaced by setting PARALLEL_FORCE_LOCAL at either the session or system level. The INSTANCES syntax is documented in the version 7 SQL Reference but is not documented in the version 8i SQL Reference.
Related
I am attempting to alter the data type of a column from a NUMBER to a VARCHAR2 in an existing database table. When running the following ALTER TABLE statement I receive the "ORA-54033: column to be modified is used in a virtual column expression" error:
ALTER TABLE table MODIFY (col1 varchar2(8));
I have already worked through the directions listed here. When looking at the SYS generated export statistics using the following query
select column_name, data_default, hidden_column
from user_tab_cols
where table_name = 'Table';
there is nothing referencing col1 in export statistics. There are about 15 hidden, SYS generated rows associated with the table and they all have a data default value of <Long>. There are no virtual columns in the DDL, nor is this column being used for any indexes or as a FK. I have also had the DBA run the following:
SELECT EXTENSION_NAME, EXTENSION, CREATOR, DROPPABLE
FROM DBA_STAT_EXTENSIONS
WHERE TABLE_NAME='Table'
and the output lines up with what I find in user_tab_cols. Where else can I look for this seemingly buried virtual column?
Iam facing a issue while altering the GTT table.
I need to find the active users on that table, Can someone help in query regarding how to find the active users on the specific object in oracle database
As far as I can tell, you didn't explain what problem you're trying to solve, but rather what you think that might help you solve it. So, let me try to guess.
Here's a global temporary table (GTT):
SQL> create global temporary table gtt (id number) on commit preserve rows;
Table created.
SQL> insert into gtt values (1);
1 row created.
SQL> commit;
Commit complete.
You're trying to alter it, but - it fails:
SQL> alter table gtt add name varchar2(10);
alter table gtt add name varchar2(10)
*
ERROR at line 1:
ORA-14450: attempt to access a transactional temp table already in use
OK, so - delete row(s) and commit, then try again:
SQL> delete from gtt;
1 row deleted.
SQL> commit;
Commit complete.
SQL> alter table gtt add name varchar2(10);
alter table gtt add name varchar2(10)
*
ERROR at line 1:
ORA-14450: attempt to access a transactional temp table already in use
Still no luck. But, if you truncate the table, then it works:
SQL> truncate table gtt;
Table truncated.
SQL> alter table gtt add name varchar2(10);
Table altered.
SQL>
If that's not what you're after, then see if this answers your question: connect as a privileged user (such as SYS, if you don't have any other) and run such a query: it shows who owns the GTT, its name, who locked it (which Oracle user) and which operating system user is it (that might help you to contact those people):
SQL> select b.owner,
2 b.object_name,
3 a.oracle_username,
4 a.os_user_name
5 from v$locked_object a, dba_objects b
6 where a.object_id = b.object_id;
OWNER OBJECT_NAM ORACLE_USERNAME OS_USER_NAME
--------------- ---------- --------------- ------------------------------
SCOTT GTT SCOTT littlefoot
SQL>
I'm using Oracle and I have a strange thing.
I dropped a table using :
drop table t_my_table, and committed.
But when I launch select * from t_my_table, it shows the data, as if the table is not dropped.
I tried disconnecting and reconnecting, it stills shows the data when I select.
And when I once again try with :
drop table t_my_table, it tells me that this table does not exist.
But if I run select again, the data is always there.
How is this possible ?
Thank you.
You mean this case?
create view t_my_table as
select 'I''m here' as txt from dual;
drop table t_my_table;
ORA-00942: table or view does not exist
But
select * from t_my_table;
TXT
--------
I'm here
solution of the most probably cause
select OBJECT_TYPE from user_objects where object_name = 'T_MY_TABLE';
OBJECT_TYPE
-------------------
VIEW
You defined a view (or other object type other than TABLE), that can't be dropped with DROP TABLE, but can be selected.
Simple check in USER_OBJECTS the OBJECT_TYPE. You may alternatively see also SYNONYM as proposed in other answer.
Note that it is not a MATERIALIZED VIEW as if you try to drop a Materialized View with DROP TABLE a different error message is raised:
ORA-12083: must use DROP MATERIALIZED VIEW to drop T_MY_TABLE
What does this return?
select * from all_synonyms
where synonym_name = 'T_MY_TABLE';
I suspect there is a synonym T_MY_TABLE that points to a table in a different schema.
drop table t_my_table purge;
Specify PURGE if you want to drop the table and release the space associated with it in a single step. If you specify PURGE, then the database does not place the table and its dependent objects into the recycle bin.
...
Using this clause is equivalent to first dropping the table and then purging it from the recycle bin. This clause lets you save one step in the process. It also provides enhanced security if you want to prevent sensitive material from appearing in the recycle bin.
Probably something different is happening.
Normal case would be:
SQL> create table t1 as select 1 a from dual;
Table T1 created.
SQL> drop table t1;
Table T1 dropped.
SQL> select * from t1;
Error starting at line : 22 in command -
select * from t1
Error at Command Line : 22 Column : 20
Error report -
SQL Error: ORA-00942: table or view does not exist
00942. 00000 - "table or view does not exist"
*Cause:
*Action:
So what was the message after the drop table?
Is t_my_table really a table?
Try select * from all_objects where lower(object_name) = 't_my_table'
I want to find the recently added column to existing table.
How to find recently added column in table or database(oracle).
Recently the table and the databases of our web application got modified and some of the table got altered.
Ideally you should have restricted access to your Production database, together with a build process which applies scripts out of source control, rather than allowing people to change things using TOAD. It's pretty hard to conduct forensics in a free-fire zone.
You can find out which tables have changed by interrogating the data dictionary:
SQL> select object_name from user_objects t
2 where t.object_type = 'TABLE'
3 and t.last_ddl_time > trunc(sysdate)
4 /
no rows selected
SQL> alter table t23 add col_3 number
2 /
Table altered.
SQL> select object_name from user_objects t
2 where t.object_type = 'TABLE'
3 and t.last_ddl_time > trunc(sysdate)
4 /
OBJECT_NAME
----------------------------------------------------------
T23
SQL>
This won't tell you what the change was, or who did it. To get better information you need a proper audit trail. At the very least you should enable auditing of DDL statements....
SQL> audit ALTER TABLE;
Audit succeeded.
SQL>
Find out more.
I put this code into SQL Developer's Worksheet:
CREATE TRIGGER T_testDSNa
before INSERT
on testDSNa
referencing new as new
for each ROW
BEGIN
SELECT S_testDSN.nextval INTO :NEW.SYSID FROM dual;
END;
I get this:
Error report -
ORA-00942: table or view does not exist
00942. 00000 - "table or view does not exist"
*Cause:
*Action:
Would anyone know why? This has worked for 3 previous tables until I tried to run the DDL to create a 4th. Alternatively, is there a better way to set up an autoincrementing PK?
The problem was lack of schema. Oracle Definition of a schema :
Collection of database objects, including logical structures such as
tables, views, sequences, stored procedures, synonyms, indexes,
clusters, and database links. A schema has the name of the user who
controls it.
If you want to know the objects accessible without alias. You have to look on [USER_OBJECTS]. Which describes the relational objects owned by the current user :
SELECT
OBJECT_NAME
, OBJECT_TYPE
, LAST_DDL_TIME
FROM USER_OBJECTS;
If you want to know the objects accessible to the current user :
SELECT
OWNER
, OBJECT_NAME
, OBJECT_TYPE
, LAST_DDL_TIME
FROM ALL_OBJECTS;
In your case to see your objects in the list of available tables you need:
SELECT * FROM ALL_OBJECTS WHERE OWNER = 'USER';
You can also alter the session to avoid alias :
ALTER SESSION SET current_schema = User;
For priviliges/ roles views you can look at :
SELECT * FROM USER_SYS_PRIVS;
SELECT * FROM USER_ROLE_PRIVS;
The last method but not the most secure to avoid alias. Is to log on with a user that has the same name as the schema.
Hoping that it can help
I was getting the same issue.
Solution: What I observed that my table which I created was surrounded by double quotes, which made it case sensitive.
So for each time I refer to my table, I need to surround it by double quotes.
CREATE TRIGGER T_testDSNa
before INSERT
on "testDSNa"
referencing new as new
for each ROW
BEGIN
SELECT S_testDSN.nextval INTO :NEW.SYSID FROM dual;
END;
refer this link: What exactly do quotation marks around the table name do?