Oracle | DBMS_FLASHBACK

Oracle DBMS_FLASHBACK Version 26ai

General Information

Library Note

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Oracle Database 26ai will be available on generic Linux platforms in January and soon on AIX and Windows

Purpose This package is the original implementation of Flashback capabilities encapsulated as a PL/SQL package. Part of this package was developed before the 10g release of command-line Flashback capabilities ... and is now obsolete. TRANSACTION_BACKOUT is a new capability added in 11g and is priceless.

AUTHID CURRENT_USER

Constants for Transaction Backout

Name	Data Type	Value
nocascade	BINARY_INTEGER	1
Default: Backs out specified transactions, expected to have no dependent transactions. If dependents an exception is raised and the error can be found in DBA_FLASHBACK_TXN_REPORT.
nocascade_force	BINARY_INTEGER	2
Backs out specified transactions, ignoring dependent transactions. Backout happens in reverse order of commit times.
noconflict_only	BINARY_INTEGER	3
Backs out changes to nonconflicting rows. The database remains consistent but atomicity is lost.
cascade	BINARY_INTEGER	4
Backs out specified transactions and all dependent transactions in a post-order fashion (children first: parents second).

Data Types Used CREATE OR REPLACE TYPE "SYS"."TXNAME_ARRAY" AS VARRAY(100) OF VARCHAR2(256);

Dependencies

DBMS_CAPTURE_ADM_INTERNAL	DBMS_STREAMS_RPC_INTERNAL	TIMESTAMP_TO_SCN
DBMS_LOGREP_EXP	DBMS_TRAN_LIB	TRANSACTION_BACKOUT_REPORT$
DBMS_STREAMS_ADM_IVK	DBMS_XSTREAM_UTL_IVK	TRANSACTION_BACKOUT_STATE$
DBMS_STREAMS_DATAPUMP	KUPM$MCP	TXNAME_ARRAY
	LOGMNR_DDL_TRIGGER_PROC	XID_ARRAY

Documented Yes: Packages and Types Reference

Exceptions

Error Code	Reason
ORA-08180	Time specified is too old
ORA-08181	Invalid system change number specified
ORA-08182	User cannot begin read-only or serializable transactions in Flashback mode
ORA-08183	User cannot enable Flashback within an uncommitted transaction
ORA-08184	User cannot enable Flashback within another Flashback session
ORA-08185	SYS cannot enable Flashback mode

First Available 9.0

Related Sysem Privileges FLASHBACK ANY TABLE

Security Model Owned by SYS with EXECUTE granted to MDSYS and the DBA, OGG_APPLY and OGG_CAPTURE roles.

Source {ORACLE_HOME}/rdbms/admin/dbmstran.sql

Subprograms

DISABLE	GET_SYSTEM_CHANGE_NUMBER
ENABLE_AT_SYSTEM_CHANGE_NUMBER	TRANSACTION_BACKOUT
ENABLE_AT_TIME

DISABLE

End Flashback Mode dbms_flashback.disable;

See Demo At Page Bottom

ENABLE_AT_SYSTEM_CHANGE_NUMBER

Enable flashback mode as of a specific SCN dbms_flashback.enable_at_system_change_number(query_scn IN NUMBER);

See Demo At Page Bottom

ENABLE_AT_TIME

Enable Flashback Mode As Of A Point-In-Time dbms_flashback.enable_at_time(query_time IN TIMESTAMP);

See Demo At Page Bottom

GET_SYSTEM_CHANGE_NUMBER

Get the current SCN dbms_flashback.get_system_change_number RETURN NUMBER;

SELECT dbms_flashback.get_system_change_number;

TRANSACTION_BACKOUT

Transaction backout interface

Overload 1 dbms_flashback.transaction_backout( numtxns NUMBER, xids xid_array, options BINARY_INTEGER DEFAULT NOCASCADE, scnhint NUMBER DEFAULT 0);

conn sys@pdbdev as sysdba

      

      shutdown immediate;

      

      startup mount;

      

      alter database archivelog;

      alter database open;

      alter system archive log current;

      alter database add supplemental log data;

      

      conn uwclass/uwclass@pdbdev

      

      CREATE TABLE t1 (

      testcol VARCHAR2(3));

      

      CREATE TABLE t2 (

      testcol VARCHAR2(3));

      

      CREATE OR REPLACE TRIGGER row_level

      BEFORE INSERT

      ON t1

      FOR EACH ROW

      

      BEGIN

        INSERT INTO t2

        VALUES

        (:NEW.testcol);

      END row_level;

      /

      

      BEGIN

        INSERT INTO t1 VALUES ('ABC');

        INSERT INTO t1 VALUES ('DEF');

        COMMIT;

        user_lock.sleep(500);

        INSERT INTO t1 VALUES ('GHI');

        INSERT INTO t1 VALUES ('JKL');

        COMMIT;

        user_lock.sleep(500);

        INSERT INTO t1 VALUES ('MNO');

        COMMIT;

        user_lock.sleep(500);

      END;

      /

      

      SELECT * FROM t1;

      SELECT * FROM t2;

      

      SELECT versions_xid, versions_startscn, versions_endscn, versions_operation, testcol

      FROM t1

      VERSIONS BETWEEN SCN MINVALUE AND MAXVALUE;

      

      desc sys.xid_array

      

      SELECT table_name

      FROM user_all_tables;

      

      set serveroutput on

      

      -- choose the middle xid

      DECLARE

       xa sys.xid_array := sys.xid_array();

      BEGIN

        xa.extend;

        dbms_output.put_line(xa.last);

        xa(1) := '04000700A2020000';

        dbms_flashback.transaction_backout(1, xa);

      END;

      /

      

      SELECT * FROM t1;

      SELECT * FROM t2;

      

      COMMIT;

      

      SELECT table_name

      FROM user_all_tables;

      

      desc sys_ktftb_sql_table

      

      SELECT * FROM sys_ktftb_sql_table;

      

      desc sys_ktftb_key_table

      

      SELECT * FROM sys_ktftb_key_table;

Overload 2 dbms_flashback.transaction_backout( numtxns NUMBER, xids IN xid_array, options IN BINARY_INTEGER DEFAULT NOCASCADE, timehint IN TIMESTAMP);

TBD

Overload 3 dbms_flashback.transaction_backout( numtxns NUMBER, names txname_array, options BINARY_INTEGER DEFAULT NOCASCADE, scnhint NUMBER DEFAULT 0);

TBD

Overload 4 dbms_flashback.transaction_backout( numtxns NUMBER, names txname_array, options BINARY_INTEGER DEFAULT NOCASCADE, timehint TIMESTAMP);

TBD

Demos

DBMS_FLASHBACK by System Change Number conn uwclass/uwclass@pdbdev SELECT COUNT(*) FROM serv_inst; CREATE TABLE sibak AS SELECT * FROM serv_inst; VARIABLE scn_save NUMBER; exec :scn_save := dbms_flashback.get_system_change_number; print scn_save SELECT COUNT(*) FROM serv_inst; DELETE FROM serv_inst; COMMIT; SELECT COUNT(*) FROM serv_inst; DECLARE TYPE si_array IS TABLE OF serv_inst%ROWTYPE; si_data si_array; CURSOR flash_cur IS SELECT * FROM serv_inst; flash_rec flash_cur%ROWTYPE; BEGIN dbms_flashback.enable_at_system_change_number(:scn_save); OPEN flash_cur; dbms_flashback.disable; LOOP FETCH flash_cur BULK COLLECT INTO si_data LIMIT 250; FORALL i IN 1..si_data.COUNT INSERT INTO serv_inst VALUES si_data(i); EXIT WHEN flash_cur%NOTFOUND; END LOOP; COMMIT; CLOSE flash_cur; END; /

DBMS_FLASHBACK by Timestamp Recovery SELECT COUNT(*) FROM SERVERS; CREATE TABLE sbak AS SELECT * FROM servers; DELETE FROM servers; COMMIT; SELECT COUNT(*) FROM servers; exec dbms_flashback.enable_at_time(SYSTIMESTAMP - 10/1440); SELECT COUNT(*) FROM servers; SELECT * FROM servers; exec dbms_flashback.disable; SELECT * FROM servers; INSERT INTO servers SELECT * FROM sbak; COMMIT;