Need some help to identify the reason for the below issue.
I have created a global temporary table as below:
Create global temporary table glo_temp_table
(
row_no NUMBER not null,
resource_id VARCHAR2(40),
company_id VARCHAR2(20),
);
This table’s data gets inserted during the runtime by a function which later used by a another function to fetch data using a cursor. This functionally works fine without any issue. Problem starts when I add an index below (to clear this is not done during the run time.):
CREATE INDEX SS ON glo_temp_table (resource_id);
Now no data will gets fetched by the cursor. Is there any specific reason for this behavior? How can I created a such a index to work properly?
Oracle db veriosn is 12c Release 12.1.0.1.0
This table only has the below constrain only.
alter table glo_temp_table
add constraint glo_temp_table_PK primary key (ROW_NO);
I am new to Oracle and for practice I have created some tables (customer, drivers, payment, booking, location, area, job, job_history) in Oracle 11g and upon select * from cat statement I have found a strange table with other created tables named "BIN$c+eOnMB3RbKSEfg/rsxtAQ==$0".I don't know why this table is created.
I tried to remove this table through
drop table BIN$c+eOnMB3RbKSEfg/rsxtAQ==$0;
but it gives error:
drop table BIN$c+*eOnMB3RbKSEfg/rsxtAQ==$0
ERROR at line 1: ORA-00933: SQL command not properly ended
what should I do to remove it?
What you see is a deleted table in the RECYCLEBIN
You may get the original name of the table with this query
SELECT original_name FROM RECYCLEBIN where OBJECT_NAME = 'BIN$c+eOnMB3RbKSEfg/rsxtAQ==$0';
Note that (with your parameter setting) if you DROP a table it is not completely removed, but moved in the recyclebin.
You may ommit this using the PURGE option.
DROP TABLE xxx PURGE;
To remove the table from the recyclebin you must qoute the name with double quotes (as this is not a valid name) and use the PURGE statement (not a DROP - which would trigger ORA-38301: can not perform DDL/DML over objects in Recycle Bin).
PURGE TABLE "BIN$c+eOnMB3RbKSEfg/rsxtAQ==$0"
Alternatively you may use the original_name obtained with the query above:
PURGE TABLE {your_original_name};
To clean up the recyclebin completely use this statement (with the propper table user)
PURGE RECYCLEBIN;
I created table t1 in Oracle 12c.
Table has data and it is partitioned on list partition and also has subpartitions.
Now I want to delete whole table and all associated partitions (and subpartitions).
Is this the right command to delete all?
DROP TABLE t1 PURGE;
The syntax is right but not preferable,
just drop without purge so that whenever you need you could have it back, if your flashback option is enabled. If your database's flashback option is in charge, you could issue this command (provided you don't use purge):
SQL> DROP TABLE T1;
SQL> FLASHBACK TABLE T1 TO BEFORE DROP RENAME TO T1_ver_2;
When you run DROP then the table is removed entirely from database, i.e. the table does not exist anymore.
If you just want to remove all data from that table run
truncate table T1 drop storage;
You can also truncate single (sub-)partition if required.
I would like to know which is the command to convert a temporary table to permanent table in Oracle.
Other issue is about the index. An index used in a temporary table will be the same used in a permanent table, if I convert it?
You can't convert a table from a temporary table to a permanent table.
You can create a new permanent table that matches the structure of the temporary table
CREATE TABLE new_permanent_table
AS
SELECT *
FROM old_temporary_table
WHERE 1=0;
Or you could get the DDL for the temporary table using the DBMS_METADATA package and manually edit the DDL to create the new permanent table.
Then you can create whatever indexes you would like on the new permanent table and drop the old temporary table. Once the old temporary table is dropped, you can rename the permanent table to use the name of the old temporary table if you would like.
I have read that one should not analyze a temp table, as it screws up the table statistics for others. What about an index? If I put an index on the table for the duration of my program, can other programs using the table be affected by that index?
Does an index affect my process, and all other processes using the table?
or Does it affect my process alone?
None of the responses have been authoritative, so I am offering said bribe.
Does an index effect my process, and all other processes using the table? or Does it effect my process alone?
I'm assuming we are talking of GLOBAL TEMPORARY tables.
Think of a temporary table as of multiple tables that are created and dropped by each process on the fly from a template stored in the system dictionary.
In Oracle, DML of a temporary table affects all processes, while data contained in the table will affect only one process that uses them.
Data in a temporary table is visible only inside the session scope. It uses TEMPORARY TABLESPACE to store both data and possible indexes.
DML for a temporary table (i. e. its layout, including column names and indexes) is visible to everybody with sufficient privileges.
This means that existence of the index will affect your process as well as other processes using the table in sense that any process that modifies data in the temporary table will also have to modify the index.
Data contained in the table (and in the index too), on the contrary, will affect only the process that created them, and will not even be visible to other processes.
IF you want one process to use the index and another one not to use it, do the following:
Create two temporary tables with same column layout
Index on one of them
Use indexed or non-indexed table depending on the process
I assume you're referring to true Oracle temporary tables and not just a regular table created temporarily and then dropped. Yes, it is safe to create indexes on the temp tables and they will be used according to the same rules as a regular tables and indexes.
[Edit]
I see you've refined your question, and here's a somewhat refined answer:
From:
Oracle® Database Administrator's Guide
10g Release 2 (10.2)
Part Number B14231-02
"Indexes can be created on temporary tables. They are also temporary and the data in the index has the same session or transaction scope as the data in the underlying table."
If you need the index for efficient processing during the scope of the transaction then I would imagine you'll have to explicitly hint it in the query because the statistics will show no rows for the table.
You're asking about two different things, indexes and statistics.
For indexes, yes, you can create indexes on the temp tables, they will be maintained as per usual.
For statistics, I recommend that you explicitly set the stats of the table to represent the average size of the table when queried. If you just let oracle gather stats by itself, the stats process isn't going to find anything in the tables (since by definition, the data in the table is local to your transaction), so it will return inaccurate results.
e.g. you can do:
exec dbms_stats.set_table_stats(user, 'my_temp_table', numrows=>10, numblks=>4)
Another tip is that if the size of the temporary table varies greatly, and within your transaction, you know how many rows are in the temp table, you can help out the optimizer by giving it that information. I find this helps out a lot if you are joining from the temp table to regular tables.
e.g., if you know the temp table has about 100 rows in it, you can:
SELECT /*+ CARDINALITY(my_temp_table 100) */ * FROM my_temp_table
Well, I tried it out and the index was visible and used by the second session. Creating a new global temporary table for your data would be safer if you really need an index.
You are also unable to create an index while any other session is accessing the table.
Here's the test case I ran:
--first session
create global temporary table index_test (val number(15))
on commit preserve rows;
create unique index idx_val on index_test(val);
--second session
insert into index_test select rownum from all_tables;
select * from index_test where val=1;
You can also use the dynamic sampling hint (10g):
select /*+ DYNAMIC_SAMPLING (3) */ val
from index_test
where val = 1;
See Ask Tom
You cannot create an index on a temporary table while it is used by another session, so answer is: No, it cannot affect any other process, because it is not possible.
An existing Index affects only your current session, because for any other session the temporary table appears empty, so it cannot access any index values.
Session 1:
SQL> create global temporary table index_test (val number(15)) on commit preserve rows;
Table created.
SQL> insert into index_test values (1);
1 row created.
SQL> commit;
Commit complete.
SQL>
Session 2 (while session 1 is still connected):
SQL> create unique index idx_val on index_test(val);
create unique index idx_val on index_test(val)
*
ERROR at line 1:
ORA-14452: attempt to create, alter or drop an index on temporary table already in use
SQL>
Back to session 1:
SQL> delete from index_test;
1 row deleted.
SQL> commit;
Commit complete.
SQL>
Session 2:
SQL> create unique index idx_val on index_test(val);
create unique index idx_val on index_test(val)
*
ERROR at line 1:
ORA-14452: attempt to create, alter or drop an index on temporary table already in use
SQL>
still failing, you first have to disconnect session 1 or table has to be truncated.
Session 1:
SQL> truncate table index_test;
Table truncated.
SQL>
Now you can create the index in Session 2:
SQL> create unique index idx_val on index_test(val);
Index created.
SQL>
This index of course will be used by any session.