【Oracle Database 12c新特性】 In-Database Archiving資料庫內歸檔

Oracle Database 12c中引入了 In-Database Archiving的新特性，該特性允許使用者透過對錶上的資料行標記為inactive不活躍的，以歸檔資料。

這些inactive的資料行可以透過壓縮排一部最佳化，且對應用來說預設不可見。可以透過一個session級別的引數來控制資料的可見與否。

透過In-Database Archiving資料庫內歸檔特性可以在單庫中存放更長週期的資料，而損耗很少的應用效能。歸檔資料還可以透過壓縮來進一步提升備份效能。

要管理一張表的In-Database Archiving，必須為表啟用ROW ARCHIVAL 並操作ORA_ARCHIVE_STATE 這個隱藏欄位。此外使用者還可以指定session級別的 ROW ARCHIVAL VISIBILITY為ACTIVE 或者ALL。

下面為演示示例：

/* 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);

commit;

/* Show all the columns in the table, including hidden columns */

SELECT SUBSTR(COLUMN_NAME,1,22), SUBSTR(DATA_TYPE,1,20), 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';

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

SQL> desc employees_indbarch

Name Null? Type

----------------------------------------- -------- ----------------------------

EMPLOYEE_ID NOT NULL NUMBER(6)

FIRST_NAME VARCHAR2(20)

LAST_NAME NOT NULL VARCHAR2(25)

EMAIL NOT NULL VARCHAR2(25)

PHONE_NUMBER VARCHAR2(20)

HIRE_DATE NOT NULL DATE

JOB_ID NOT NULL VARCHAR2(10)

SALARY NUMBER(8,2)

COMMISSION_PCT NUMBER(2,2)

MANAGER_ID NUMBER(6)

DEPARTMENT_ID NUMBER(4)

1* select COLUMN_NAME,COLUMN_ID,DATA_TYPE from dba_tab_cols where table_name=upper('employees_indbarch')

SQL> /

COLUMN_NAME COLUMN_ID DATA_TYPE

-------------------- --------- --------------------

DEPARTMENT_ID 11 NUMBER

MANAGER_ID 10 NUMBER

COMMISSION_PCT 9 NUMBER

SALARY 8 NUMBER

JOB_ID 7 VARCHAR2

HIRE_DATE 6 DATE

PHONE_NUMBER 5 VARCHAR2

EMAIL 4 VARCHAR2

LAST_NAME 3 VARCHAR2

FIRST_NAME 2 VARCHAR2

EMPLOYEE_ID 1 NUMBER

ORA_ARCHIVE_STATE VARCHAR2

SQL> select dump(ORA_ARCHIVE_STATE,16),dump(EMPLOYEE_ID,16),dbms_rowid.rowid_block_number(rowid),dbms_rowid.rowid_relative_fno(rowid) from employees_indbarch;

DUMP(ORA_ARCHIVE_STA DUMP(EMPLOYEE_ID,16) DBMS_ROWID.ROWID_BLOCK_NUMBER(ROWID) DBMS_ROWID.ROWID_RELATIVE_FNO(ROWID)

-------------------- -------------------- ------------------------------------ ------------------------------------

Typ=1 Len=1: 30 Typ=2 Len=3: c2,3,34 109465 1

Typ=1 Len=2: 32,30 Typ=2 Len=3: c2,3,35 109465 1

SQL> alter system flush buffer_cache;

System altered.

SQL> alter system dump datafile 1 block 109465;

System altered.

tl: 73 fb: --H-FL-- lb: 0x0 cc: 12

col 0: [ 1] 30

col 1: [ 3] c2 03 34

col 2: [ 5] 53 63 6f 74 74

col 3: [ 5] 54 69 67 65 72

col 4: [23]

73 63 6f 74 74 2e 74 69 67 65 72 40 65 78 61 6d 70 6c 65 2e 63 6f 6d

col 5: *NULL*

col 6: [ 7] 78 6d 05 15 01 01 01

col 7: [ 7] 49 54 5f 50 52 4f 47

col 8: [ 2] c3 06

col 9: *NULL*

col 10: [ 3] c2 02 04

col 11: [ 2] c1 3d

tab 0, row 1, @0x1ecc

tl: 70 fb: --H-FL-- lb: 0x2 cc: 12

col 0: [ 2] 32 30

col 1: [ 3] c2 03 35

col 2: [ 4] 4a 61 6e 65

col 3: [ 4] 4c 69 6f 6e

col 4: [21]

6a 61 6e 65 2e 6c 69 6f 6e 40 65 78 61 6d 70 6c 65 2e 63 6f 6d

col 5: *NULL*

col 6: [ 7] 78 6d 06 0b 01 01 01

col 7: [ 7] 49 54 5f 50 52 4f 47

col 8: [ 2] c3 06

col 9: *NULL*

col 10: [ 3] c2 02 04

col 11: [ 2] c1 3d

可以看到這裡 ORA_ARCHIVE_STATE是實際存放在塊裡的row piece上的第一個欄位，型別為varchar2(4000);
In-Database Archiving的限制：

§ ILM is not supported with OLTP table compression for in-database archiving. Segment-level ILM and compression is supported if partitioned on the ORA_ARCHIVE_STATE column.

ORA_ARCHIVE_STATE相關：

/* constants specifying ROW ARCHIVAL state */
archive_state_active constant varchar2(1) := ‘0’;
archive_state_archived constant varchar2(1) := ‘1’;

/*
* description – Given a value for the ORA_ARCHIVE_STATE column this
* function returns the mapping for the value.
*
* value – “0”, “1” or other values from the ORA_ARCHIVE_STATE column of
* a row archival enabled table
* returns either “archive_state_active” or “archive_state_archived”
*/

Oracle Database 12c新特性 In-Database Archiving資料庫內歸檔

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