In-Database Archiving enables you to archive rows within a table by marking them as inactive. These inactive rows are in the database and can be optimized using compression, but are not visible to an application. The data in these rows is available for compliance purposes if needed by setting a session parameter.
With In-Database Archiving you can store more data for a longer period of time within a single database, without compromising application performance. Archived data can be compressed to help improve backup performance, and updates to archived data can be deferred during application upgrades to improve the performance of upgrades.
To manage In-Database Archiving for a table, you must enable ROW ARCHIVAL for the table and manipulate the ORA_ARCHIVE_STATE hidden column of the table. Optionally, you specify either ACTIVE or ALL for the ROW ARCHIVAL VISIBILITY session parameter.
For example, you can use the SQL statements similar to those in Example 5-9 to hide or show rows in a table. The purpose is to display only active data in most situations, but to maintain all data in case it is needed in specific situations.
Oracle Database SQL Language Reference for information about using SQL statements to manage In-Database Archiving features
Oracle Database PL/SQL Packages and Types Reference for information about the ARCHIVESTATENAME function in the DBMS_ILM package
Example 5-9 Using In-Database Archiving
/* Set visibility to ACTIVE to display only active rows of a table.*/
ALTER SESSION SET ROW ARCHIVAL VISIBILITY = ACTIVE;
CREATE TABLE employees_indbarch
(employee_id NUMBER(6) NOT NULL,
first_name VARCHAR2(20), last_name VARCHAR2(25) NOT NULL,
email VARCHAR2(25) NOT NULL, phone_number VARCHAR2(20),
hire_date DATE NOT NULL, job_id VARCHAR2(10) NOT NULL, salary NUMBER(8,2),
commission_pct NUMBER(2,2), manager_id NUMBER(6), department_id NUMBER(4)) ROW ARCHIVAL;
INSERT INTO employees_indbarch(employee_id, first_name, last_name, email,
hire_date, job_id, salary, manager_id, department_id)
VALUES (251, 'Scott', 'Tiger', 'scott.tiger@example.com', '21-MAY-2009',
'IT_PROG', 50000, 103, 60);
INSERT INTO employees_indbarch(employee_id, first_name, last_name, email,
hire_date, job_id, salary, manager_id, department_id)
VALUES (252, 'Jane', 'Lion', 'jane.lion@example.com', '11-JUN-2009',
'IT_PROG', 50000, 103, 60);
/* Show all the columns in the table, including hidden columns */
SELECT SUBSTR(COLUMN_NAME,1,22) NAME, SUBSTR(DATA_TYPE,1,20) DATA_TYPE, COLUMN_ID AS COL_ID,
SEGMENT_COLUMN_ID AS SEG_COL_ID, INTERNAL_COLUMN_ID AS INT_COL_ID, HIDDEN_COLUMN, CHAR_LENGTH
FROM USER_TAB_COLS WHERE TABLE_NAME='EMPLOYEES_INDBARCH';
NAME DATA_TYPE COL_ID SEG_COL_ID INT_COL_ID HID CHAR_LENGTH
---------------------- -------------------- ---------- ---------- ---------- --- -----------
ORA_ARCHIVE_STATE VARCHAR2 1 1 YES 4000
EMPLOYEE_ID NUMBER 1 2 2 NO 0
FIRST_NAME VARCHAR2 2 3 3 NO 20
LAST_NAME VARCHAR2 3 4 4 NO 25
EMAIL VARCHAR2 4 5 5 NO 25
PHONE_NUMBER VARCHAR2 5 6 6 NO 20
HIRE_DATE DATE 6 7 7 NO 0
JOB_ID VARCHAR2 7 8 8 NO 10
SALARY NUMBER 8 9 9 NO 0
COMMISSION_PCT NUMBER 9 10 10 NO 0
MANAGER_ID NUMBER 10 11 11 NO 0
DEPARTMENT_ID NUMBER 11 12 12 NO 0
/* Decrease the ORA_ARCHIVE_STATE column size to improve formatting in queries */
COLUMN ORA_ARCHIVE_STATE FORMAT a18;
/* The default value for ORA_ARCHIVE_STATE is '0', which means active */
SELECT employee_id, ORA_ARCHIVE_STATE FROM employees_indbarch;
EMPLOYEE_ID ORA_ARCHIVE_STATE
----------- ------------------
251 0
252 0
/* Insert a value into ORA_ARCHIVE_STATE to set inactive */
UPDATE employees_indbarch SET ORA_ARCHIVE_STATE = '20' WHERE employee_id = 252;
/* Only active records are in the following query */
SELECT employee_id, ORA_ARCHIVE_STATE FROM employees_indbarch;
EMPLOYEE_ID ORA_ARCHIVE_STATE
----------- ------------------
251 0
/* Set visibility to ALL to display all records */
ALTER SESSION SET ROW ARCHIVAL VISIBILITY = ALL;
SELECT employee_id, ORA_ARCHIVE_STATE FROM employees_indbarch;
EMPLOYEE_ID ORA_ARCHIVE_STATE
----------- ------------------
251 0
252 20