Delete vs truncate

Hi,
We are using Oracle and we have a daily job of loading data to a table.
The existing data needs to be cleaned and fresh insert need to be done. Should I use Delete or truncate to clean the data.
If any error occurs i need to have old data ie previous load in my table.
so which option should i use? Delete or truncate
Thanks
Harshini

Given this requirement:
If any error occurs i need to have old data ie previous load in my table.I would suggest you consider a process that uses partition exchange.
Such as:
Create a work_table, with the same columns as your target_table, with a single partition. It could really be partitioned on anything, since you want only 1. Probably a range partition where values < maxvalue.
Add local indexes to your work_table, that are the same type and cover the same columns as the indexes on your target_table.
For each load:
Truncate table work_table; -- to instantly empty it
insert or load your data into work_table
alter table work_table exchange partition the_only_partition with table target_table including indexes without validation;Now your current data is in target_table, and your previous data is in work_table. At no point were you stuck with only some of your data. If your data is bad, you can just do the partition exchange to put the previous data back.

Similar Messages

Delete or Truncate statement for data purging

Hi,
I am writting a stored procedure to purge data from table every month. There is no constraint on table column except primary key.
I am using 'delete' statement as it records an entry in the transaction log for each deleted row. But it's a slow process compared to 'Truncate' statement.
Can you please suggest what should I choose (Delete or truncate) as per best practice.
Thanks
Sandy
SandyLeo

If you want to delete all rows in the table use TRUNCATE, otherwise I would suggest the below technique
--SQL2008 and onwards
insert into Archive..db
select getdate(),d.*
from (delete from db1
output deleted.*
where col=<value>
) d
go
Best Regards,Uri Dimant SQL Server MVP,
http://sqlblog.com/blogs/uri_dimant/
MS SQL optimization: MS SQL Development and Optimization
MS SQL Consulting:
Large scale of database and data cleansing
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DELETE, DROP, TRUNCATE의 비교

제품 : ORACLE SERVER
작성날짜 : 1998-06-23
DELETE, DROP, TRUNCATE의 비교
=============================
TABLE에서 행을 삭제하는 세 가지 OPTION의 비교
TABLE에서 모든 행을 삭제하는 방법에는 다음과 같은 세 가지 OPTION이 있다.
1. DELETE 명령어 사용
     DELETE 명령어를 사용하여 TABLE의 행을 삭제할 수 있다.
     예를 들어 EMP TABLE에서 모든 행을 삭제하는 명령문은 다음과 같다.
     DELETE FROM emp;
     O. DELETE 문을 사용할 때 TABLE이나 CLUSTER에 행이 많으면 행이 삭제
될 때마다 많은 SYSTEM 자원이 소모된다. 예를 들어 CPU 시간, REDO
LOG 영역, TABLE이나 INDEX에 대한 ROLLBACK SEGMENT 영역 등의 자
원이 필요하다.
     O. TRIGGER가 걸려 있다면 각 행이 삭제될 때 실행된다.
     O. 이전에 할당되었던 영역은 삭제되어 빈 TABLE이나 CLUSTER에 그대로
남아 있게 된다.
2. DROP 과 CREATE 명령어 사용
     TABLE을 삭제한 다음 재생성할 수 있다. 예를 들어 EMP TABLE을 삭제하
고 재생성하는 명령문은 다음과 같다.
     DROP TABLE emp;
     CREATE TABLE emp (......);
     O. TABLE이나 CLUSTER를 삭제하고 재생성하면 모든 관련된 INDEX,
CONSTRAINT,TRIGGER도 삭제되며, 삭제된 TABLE이나 CLUSTERED
     TABLE에 종속된 OBJECTS는 무효화 된다.
     O. 삭제된 TABLE이나 CLUSTERED TABLE에 부여된 권한도 삭제된다.
3. TRUNCATE 명령어 사용
     SQL명령어 TRUNCATE를 사용하여 TABLE의 모든 행을 삭제할 수 있다.
     예를 들어 EMP TABLE을 잘라내는 명령문은 다음과 같다.
     TRUNCATE TABLE emp:
     O. TRUNCATE 명령어는 TABLE이나 CLUSTER에서 모든 행을 삭제하는 빠르
고 효율적인 방법이다.
     O. TRUNCATE 명령어는 어떤 ROLLBACK 정보도 만들지 않고 즉시 COMMIT
한다.
     O. TRUNCATE 명령어는 DDL 명령문으로 ROLLBACK될 수 없다.
     O. TRUNCATE 명령문은 잘라 버릴 TABLE과 관련된 구조(CONSTRAINT,
     TRIGGER 등)과 권한에 영향을 주지 않는다.
     O. TRUNCATE 명령문은 현재 TABLE에 할당된 영역을 잘라버린 후에 포함
되는 TABLESPACE로 복귀되도록 지정한다.
(REUSE STORAGE, DROP STORAGE OPTION 사용)
     - DROP STORAGE OPTION 사용 시 : TABLE EXTENTS 수를 MINEXTENTS의
     원래 설정값으로 줄인다.
               해제된 확장영역은 SYSTEM에 복귀되며,
          다른 OBJECTS가 사용할 수 있다.
- REUSE STORAGE OPTION 사용 시 : 현재 TABLE이나 CLUSTER에 할당된
모든 영역이 할당된 채로 남아 있도록
지정한다.
     O. TRUNCATE 명령문이 TABLE에서 ROW를 삭제하면 해당 TABLE에 걸려 있는
TRIGGER는 실행되지 않는다.
     O. AUDIT 기능이 ENABLE되어 있으면, TRUNCATE 명령문은 DELETE 문에 해
당하는 AUDIT 정보를 생성하지 않는다. 대신 발생한 TRUNCATE 명령문
에 대한 단일 AUDIT RECORD를 생성한다.
* HASH CLUSTER는 잘라버릴 수 없다.
또한 HASH CLUSTER나 INDEX CLUSTER 내의 TABLE도 개별적으로 잘라버릴 수
없다.
INDEX CLUSTER를 잘라버리면 CLUSTER에 있는 모든 TABLE의 모든 ROW가 삭제
된다.
모든 ROW가 각각의 CLUSTERED TABLE에서 삭제되어야 한다면 DELETE 명령어를
사용하거나 TABLE을 삭제하고 재생성한다.

There Oracle says us about CASCADE keyword in ALTER TYPE ... DROP METHOD statement
http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96540/statements_43a.htm#2078974
CASCADE Clause
Specify the CASCADE clause if you want to propagate the type change to dependent types and tables. Oracle Database aborts the statement if any errors are found in the dependent types or tables unless you also specify FORCE.
Try to find the dependences between your super - and subtypes.
It would be better if you specify your complete objects
hierarchy in the example.
Rgds.

What are the differences between delete and truncate statements.

i need few differences between executing both the above statements.like what is the effect they are going to make on the data in the table and regarding the table
spaces

One of the main diffrence TRUNCATE is DDL while DELETE is DML thats why
you neednt to commit/rollbacked after TRUNCATING table.
If you have master/child table then TRUNCATING master table will not concerned
with child table data ,it will concerned with FK enabled KEY truncate is DDL.
While DML will concerned with detail table data when deleting master table data.
SQL> DESC dept
Name                                      Null?    Type
DEPTNO                                    NOT NULL NUMBER(2)
DNAME                                              VARCHAR2(14)
LOC                                                VARCHAR2(13)
SQL> DESC emp
Name                                      Null?    Type
EMPNO                                     NOT NULL NUMBER(4)
ENAME                                              VARCHAR2(10)
JOB                                                VARCHAR2(9)
MGR                                                NUMBER(4)
HIREDATE                                           DATE
SAL                                                NUMBER(7,2)
COMM                                               NUMBER(7,2)
DEPTNO                                    NOT NULL NUMBER(2)
SQL> TRUNCATE TABLE emp
2 /
Table truncated.
SQL> TRUNCATE TABLE dept
2 /
TRUNCATE TABLE dept
ERROR at line 1:
ORA-02266: unique/primary keys in table referenced by enabled foreign keys
SQL> Unless you dont disable/drop FK key from child table you cant TUNCATE master
table data.
Khurram

Delete vs truncate on materilized view

is it possible to truncate materilized view? if yes, is it faster than using delete from materialized view?
thanks.

user8837158 wrote:
is it possible to truncate materilized view? YES, for example;
dbms_mview.refresh( 'MY_MVIW_NAME' , 'C', atomic_refresh => FALSE ); => This does a TRUNCATE
if yes, is it faster than using delete from materialized view? Yes it is faster ; TRUNCATE is a DDL, no need as much undo as a DELETE, where a DELETE is a DML
DELETE operation will cause all DELETE triggers on the table to fire. Where with TRUNCATE no triggers will be fired.
thanks.

Delete as Truncate

Dears,
i don't have tablespace enough and i need to delete with condition but as i know delete statment not delete storge as truncate statment do
how can use delete statment as (delete rows with condition and remove storge also)

user8929623 wrote:
Dears,
i don't have tablespace enough and i need to delete with condition but as i know delete statment not delete storge as truncate statment do
how can use delete statment as (delete rows with condition and remove storge also)What is your database and OS version?
You can delete from your table(some conditions) and after can shrink this as:
alter table <your_table> enable row movement;
alter table <your_table> shrink space cascade;In additionally see below links;
http://download.oracle.com/docs/cd/B19306_01/server.102/b14231/schema.htm#CBBBIADA
http://download.oracle.com/docs/cd/B28359_01/server.111/b28286/statements_3001.htm
Edited by: Chinar on Jun 28, 2010 3:30 AM

How can I know if a table is truncated or deleted in any moment?

Hello, How can I know (if I can) if a table is being deleted or truncated at any moment over the time?
Thanks

This may help you
SQL> desc user_tab_modifications
Name                                      Null?    Type
TABLE_NAME                                         VARCHAR2(30)
PARTITION_NAME                                     VARCHAR2(30)
SUBPARTITION_NAME                                  VARCHAR2(30)
INSERTS                                            NUMBER
UPDATES                                            NUMBER
DELETES                                            NUMBER
TIMESTAMP                                          DATE
TRUNCATED                                          VARCHAR2(3)
DROP_SEGMENTS                                      NUMBER

RSECLOG - how do i delete/truncate this table???

Hello BW people,
we turned on auth analysis 6 or 7 months ago and now we have a 260 gb table and i am trying to delete the logs manually thru RSECPROT but it is taking forever to delete one log (approx 30 mins).
is there either a program in sap or a manual way of deleteing or truncating this table?
any help would be very much appreciated.

Thanks Jorge,
this has worked perfectly.
I thought there might be a sap program to do this, but this worked.
thx,
Erik

Different between drop,delete,truncate.

hi.
kindly what is the different between drop table,delete table,truncate table.
thanke you all .

Hi
Drop is a ddl statement which removes the existence of the table along with the data.
Delete is a dml statement which removes only the data from the table.
Truncate is a ddl statement which removes only the data from the table.
1) You can specify condition in delete statement which would remove only the specific data from the table. You cannot specify condition in truncate statement so all the data would be remove.
2) Delete keeps the records in buffers/undo segment so that you can rollback. Whereas truncate does not so you cannot rollback, moreover implicit commit is done on issuing of truncate
3) Truncate also resets high water mark of the table whereas delete does not.
Regards

How to delete a line in smart forms

Hi all
i have data in my itab in following format
Month   1 2 3   4   5   6 7   total
nov      a   a a   a   a a a    7a
dec       P   A P   P A p A   4p
                                             3a
i have to print data from col month to 7 in main area of the table in smart forms but it shows the 3rd line as well(an empty extra line) . is there any way that i may be able to delete or truncate third line ? as i have to print total below some where.
Regards
Ammad

Hi Ammad
i have a solution to ur question.
well u only want to print a line in the smartform Main window table if u have data in the first field of ur internal table lets take name as T_FINAL.
So u want to print lines in Smartform if T_Final-Field1 (which for month) is not empty.
For this go to the Condition tab of the Line (ROW) inside ur MAIN AREA In TABLE which must be there in any window probably in the Main window.
Double click on the Line (ROW) in MAIN AREA, It will contain 2 tabs Output option and Condition.
Click On condition and write under FIELD NAME the field of ur internal table WA u r using in TABLE for eg T_Final-Field1 if its Internal table with header line or if u r using a separate Work area use the work area like WA_Final-FIELD1, then click on the Square button just in front of it to select an RELATIONAL OPERATOR , put there the RELATIONAL OPERATOR as "Not Equal to" and in the comparison value column write a space quoted with single quotation as ' '.
After u do this any line encountered with its first field of WA_FINAL i.e wa_final-field1as empty wont be printed.
This Reloves ur issue.
Regards,
Akash Rana

Deleting data from a very large log table (custom table in our namespace)

Hello,
I have been tasked with clearing a log table in our landscape to only include the most recent entries. Is it possible to do this given that the table has already got 230 000 000 entries and will need to keep around 600 000 recent entries?
Should I do this via ABAP and if so, how? Thanks,
Samir

Hi,
so you are going to keep 0,3 % of your data?
If you should do it in ABAP or on the database is your decission.
In my opinion doing things on the database directly should be done
exceptional cases only e.g. for one time actions or actions that have to
be done very rarely and with different parameters / options. Regular
and similar tasks should be done in ABAP i think.
In any case i would not delete the majority of the records but copy
the records to keep in an empty table with the same structure, delete the
table as a whole (check clients!) and "copy" the new table back in ABAP
or rename the new table to the old table after droping the old table on the database.
If you have only one client you can copy the data you need in a new
table and truncate the old table (fast deletion for all clients). If you have
data to keep for other clients as well check how much data it is per client
in comparison to the total number of lines (if only a small fraction, pefer copying
them too).
On the database you can use CTAS (create table as select) and drop table and
rename table. Those commands shoudl be very efficient but work client independently.
If you have to consider clients SELECT; INSERT; DELETE or TRUNCATE (depends on if you have
copied all data considering clients) are
your friends.
Kind regards,
Hermann

Deleted Data, no increase in free space......

We have deleted in excess of 1.2M rows of data from 3 tables within the database, but have seen no real increase in the amount of freespace in the datafiles, what else do i need to do or missing,,,,
TY, newbie, WAR.

Hi,
Oracle datafiles cannot release the extents acquired automatically when data is deleted. Any new data added is always appended by acquiring new extents. Truncation is the only way of reducing the datafile size.However, if all data cannot be deleted, then truncation cannot be used. An idea would be to delete the reqd number of records, then use export utility to take a dump of the remaining data, then truncate the table, and then import the data back into the table. (during import, you should specify the option 'Ignore error due to object existence...' etc as 'yes', so that the data will be appended to the empty table.)
Regards
Sanchayan
null

Delete DML statment tales more time than Update or Insert.

i want to know whether a delete statement takes more time than an update or insert DML command. Please help in solving the doubt.
Regards.

I agree: the amount of ROLLBACK (called UNDO) and ROLLFORWARD (called REDO) information written by the various statement has a crucial impact on the speed.
I did some simple benchmarks for INSERT, UPDATE and DELETE using a 1 million row simple table. As an alternative to the long UPDATEs and DELETEs, I tested also the usual workarounds (which have only partial applicability).
Here are the conclusions (quite important in my opinion, but not to be taken as universal truth):
1. Duration of DML statements for 1 million rows operations (with the size of redo generated):
--- INSERT: 3.5 sec (redo: 3.8 MB)
--- UPDATE: 24.8 sec (redo: 240 MB)
--- DELETE: 26.1 sec (redo: 228 MB)
2. Replacement of DELETE with TRUNCATE
--- DELETE: 26.1 sec (rollback: 228 MB)
--- TRUNCATE: 0.1 sec (rollback: 0.1 MB)
3. Replacement of UPDATE with CREATE new TABLE AS SELECT (followed by DROP ols and RENAME new AS old)
--- UPDATE: 24.8 sec (redo_size: 240 MB)
--- replacement: 3.5 sec (rollback: 0.3 MB)
-- * Preparation *
CREATE TABLE ao AS
    SELECT rownum AS id,
          'N' || rownum AS name
     FROM all_objects, all_objects
    WHERE rownum <= 1000000;
CREATE OR REPLACE PROCEDURE print_my_stat(p_name IN v$statname.NAME%TYPE) IS
    v_value v$mystat.VALUE%TYPE;
BEGIN
    SELECT b.VALUE
      INTO v_value
      FROM v$statname a,
           v$mystat   b
     WHERE a.statistic# = b.statistic# AND lower(a.NAME) LIKE lower(p_name);
    dbms_output.put_line('*' || p_name || ': ' || v_value);
END print_my_stat;
-- * Test 1: Comparison of INSERT, UPDATE and DELETE *
CREATE TABLE ao1 AS
    SELECT * FROM ao WHERE 1 = 2;
exec print_my_stat('redo_size')
*redo_size= 277,220,544
INSERT INTO ao1 SELECT * FROM ao;
1000000 rows inserted
executed in 3.465 seconds
exec print_my_stat('redo_size')
*redo_size= 301,058,852
commit;
UPDATE ao1 SET name = 'M' || SUBSTR(name, 2);
1000000 rows updated
executed in 24.786 seconds
exec print_my_stat('redo_size')
*redo_size= 545,996,280
commit;
DELETE FROM ao1;
1000000 rows deleted
executed in 26.128 seconds
exec print_my_stat('redo_size')
*redo_size= 783,655,196
commit;
-- * Test 2: Replace DELETE with TRUNCATE *
DROP TABLE ao1;
CREATE TABLE ao1 AS
    SELECT * FROM ao;
exec print_my_stat('redo_size')
*redo_size= 807,554,512
TRUNCATE TABLE ao1;
executed in 0.08 seconds
exec print_my_stat('redo_size')
*redo_size= 807,616,528
-- * Test 3: Replace UPDATE with CREATE TABLE AS SELECT *
INSERT INTO ao1 SELECT * FROM ao;
commit;
exec print_my_stat('redo_size')
*redo_size= 831,525,556
CREATE TABLE ao2 AS
    SELECT id, 'M' || SUBSTR(name, 2) name FROM ao1;
executed in 3.125 seconds
DROP TABLE ao1;
executed in 0.32 seconds
RENAME ao2 TO ao1;
executed in 0.01 seconds
exec print_my_stat('redo_size')
*redo_size= 831,797,608

Add Delete Characters to rename function

At times it is useful to remove characters from file names. This is not possible at present with the rename function. (As a work around, I wrote an AppleScript to that does it in the Finder.)
Add thge following options:
"Delete" -- box to enter number -- "characters from front of file name".
"Delete" -- box to enter number -- "characters from end of file name".
The extension should be preserved, unless change is requested with another change option.
Because the underscore character "_" is used in many file names, it would also be nice to have:
"Delete" -- box to enter number -- "characters before '_' ".
"Delete" -- box to enter number -- "characters after '_' ".
If for any reason the deletion of more characters after the '_' is requested than there are characters in a file name, only the existing characters should be deleted. File extensions should never be deleted or truncated.

Agree - refer to my request a couple of days ago
johnbeardy, "Batch rename improvements" #, 18 Aug 2005 12:38 am

Cannot able to delete the Analytical Workspace and its objects.

Hi,
My Analytical workspace (11.2.0.2 B) seems to be corrupted. I could not able to attach the workspace through AWM and i cannot even able to delete it. I found there is no other session attached the Work space. I used the below query to find the locks on the work space.
SELECT
username || ' ('||SID||','||serial#||','||
DECODE(server,
'DEDICATED','D',
'SHARED', 'S', 'U')||')' usn,
gvawo.inst_id,
owner||'.'||daws.aw_name||' ('||
DECODE(attach_mode,
'READ WRITE', 'RW',
'READ ONLY', 'RO',
'MULTIWRITE', 'MW',
'EXCLUSIVE', 'XW', attach_mode)||')' aw,
generation
FROM
DBA_AWS daws,
gv$aw_olap gvawo,
gv$aw_calc gvawc,
gv$session gvses
WHERE
daws.aw_number = gvawo.aw_number
AND SID = gvawo.session_id
AND gvawc.session_id = SID
AND gvawo.inst_id = gvawc.inst_id
AND gvses.inst_id = gvawc.inst_id
ORDER BY
username,
SID,
daws.aw_name
When i try to delete the work space i am getting the following error. I cannot able to attach the work space also.
An error has occurred on the server
Error class: Express Failure
Server error descriptions:
DPR: cannot create server cursor, Generic at TxsOqDefinitionManager::generic<CommitRoot>
INI: XOQ-00703: error executing OLAP DML command "(AW DELETE DWH_REP.SAMPLE : ORA-37163: cannot delete or truncate AW with dependent CUBES or CUBE DIMENSIONS
*)", Generic at TxsOqAWManager::executeCommand*
Please help me to resolve this.
Regards,
Raghav

Hi,
When i try to execute your statement through Toad, i am getting the below error.
ORA-03113: end-of-file on communication channel
But the same is working for other AW which has not corrupted.
When i try to open the corrupted work space through AWM, i get the below error.
Unable to attach DWH_REP.SAMPLE Analytic Workspace read write
java.sql.SQLException: No more data to read from socket
at oracle.olap.awm.connection.AwAttachmentManager.attachInThread(Unknown Source)
at oracle.olap.awm.navigator.node.WorkspaceNode.setExpanded(Unknown Source)
at oracle.bali.ewt.dTree.DTreeButtonDecoration.processMouseEvent(Unknown Source)
at oracle.bali.ewt.dTree.DTreeStackingDecoration.processMouseEvent(Unknown Source)
at oracle.bali.ewt.dTree.DTree.processMouseEvent(Unknown Source)
at oracle.olap.awm.navigator.Navigator.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at oracle.bali.ewt.LWComponent.processEventImpl(Unknown Source)
at oracle.bali.ewt.dTree.DTree.processEventImpl(Unknown Source)
at oracle.bali.ewt.LWComponent.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$000(Unknown Source)
at java.awt.EventQueue$1.run(Unknown Source)
at java.awt.EventQueue$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$2.run(Unknown Source)
at java.awt.EventQueue$2.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
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at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
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Delete vs truncate

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