Kenapa count(*) ==> 0 ?
Karena SCN yg dipakai adalah SCN SETELAH perintah delete/commit
dijalankan (=current SCN).
Padahal data yg akan dibaca adalah data masa lalu, dengan SCN masa
lalu juga, yaitu SCN sebelum commit.
Contoh:
SQL> SELECT COUNT(*) FROM test_tbl;
COUNT(*)
----------
4
SQL> select DBMS_FLASHBACK.GET_SYSTEM_CHANGE_NUMBER from dual;
GET_SYSTEM_CHANGE_NUMBER
------------------------
447239
SQL> DELETE FROM test_tbl;
4 rows deleted.
SQL> COMMIT;
Commit complete.
SQL> select DBMS_FLASHBACK.GET_SYSTEM_CHANGE_NUMBER from dual;
GET_SYSTEM_CHANGE_NUMBER
------------------------
447247
SQL> SELECT COUNT(*) FROM test_tbl;
COUNT(*)
----------
0
--SCN sebelum delete/commit
SQL> SELECT COUNT(*) FROM test_tbl AS OF SCN 447239;
COUNT(*)
----------
4
--SCN setelah delete/commit
SQL> SELECT COUNT(*) FROM test_tbl AS OF SCN 447247;
COUNT(*)
----------
0
CMIIW,
Bowo
--- In [email protected], "betabetha ." <[EMAIL PROTECTED]>
wrote:
>
> Siang,
>
> Saya membaca bahwa metode flasback untuk pencarian data (recovery
> data) ini selain menggunakan waktu (AS OF timestamp) bisa juga
dengan
> menggunakan SCN (System_Change_Number). Ternyata recovery dengan
> menggunakan SCN ini tidak berhasil, kenapa ya? berikut ini saya
> tampilkan query saya:
> SQL> select count(*) from d_master.t_bank;
> COUNT(*)
> ----------------
> 177
> SQL> delete d_master.t_bank;
> 177 rows deleted.
> SQL> select DBMS_FLASHBACK. GET_SYSTEM_CHANGE_NUMBER from dual;
>
> GET_SYSTEM_CHANGE_NUMBER
> -----------------------------------------------------
> 3138345
> dan ini hasilnya record tidak ditemukan:
> SQL> select count(*) from d_master.t_bank AS OF SCN 3138345;
>
> COUNT(*)
> ----------------
> 0
>
> salam
> betty
>
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