A Oracle tem SCN (System Change Numbers):http://docs.oracle.com/cd/E11882_01/server.112/e10713/transact.htm#CNCPT039
Use uma pseudocoluna ORA_ROWSCN para examinar o SCN atual das linhas:
http://docs.oracle.com/cd/B28359_01/server.111/b28286/pseudocolumns007.htm#SQLRF51145
Um exemplo:
SELECT ora_rowscn, t.* From test t;
Demo --> http://www.sqlfiddle.com/#!4/535bc /1
(No SQLFiddle, commits explícitos aparentemente não funcionam - em um banco de dados real, cada commit aumenta o SCN).
Um exemplo em um banco de dados "real":
CREATE TABLE test(
id int,
value int
);
INSERT INTO test VALUES(1,0);
COMMIT;
SELECT ora_rowscn, t.* FROM test t;
ORA_ROWSCN ID VALUE
---------- ---------- ----------
3160728 1 0
UPDATE test SET value = value + 1 WHERE id = 1;
COMMIT;
SELECT ora_rowscn, t.* FROM test t;
ORA_ROWSCN ID VALUE
---------- ---------- ----------
3161657 1 1
UPDATE test SET value = value + 1 WHERE id = 1;
COMMIT;
SELECT ora_rowscn, t.* FROM test t;
ORA_ROWSCN ID VALUE
---------- ---------- ----------
3161695 1 2
Se o SCN da transação for conhecido, podemos usar uma consulta de flashback para obter um valor anterior da linha:
http://docs.oracle.com/cd/B28359_01/appdev.111/b28424/adfns_flashback.htm#g1026131
Um exemplo:
SELECT t.*,
versions_startscn, versions_starttime,
versions_endscn, versions_endtime,
versions_xid, versions_operation
FROM test VERSIONS BETWEEN SCN MINVALUE AND MAXVALUE t;
ID VALUE VERSIONS_STARTSCN VERSIONS_STARTTIME VERSIONS_ENDSCN VERSIONS_ENDTIME VERSIONS_XID VERSIONS_OPERATION
---------- ---------- ----------------- ------------------- --------------- ------------------- ---------------- ------------------
1 2 3161695 13/12/10 08:19:39 06000300EA070000 U
1 1 3161657 13/12/10 08:18:39 3161695 13/12/10 08:19:39 06001200EA070000 U
1 0 3161657 13/12/10 08:18:39
SELECT t.*,
versions_startscn, versions_starttime,
versions_endscn, versions_endtime,
versions_xid, versions_operation
FROM test VERSIONS BETWEEN SCN 3161657 AND 3161657 t;
ID VALUE VERSIONS_STARTSCN VERSIONS_STARTTIME VERSIONS_ENDSCN VERSIONS_ENDTIME VERSIONS_XID VERSIONS_OPERATION
---------- ---------- ----------------- ------------------- --------------- ------------------- ---------------- ------------------
1 1 3161657 13/12/10 08:18:39 06001200EA070000 U
