Kscope19 - Flashback: Good for Developers as well as DBAs

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Flashback - the forgotten feature
Connor McDonald
Database Advocate

flashback
11

several technologies
12

flashback query
flashback table
flashback drop
flashback database
flashback transaction
flashback data archive

flashback
query
14

controversy
15

you have always...
16

.. been using flashback query
17

revision
18

SQL> update EMP
2 set SAL = SAL * 1.10
3 /
14 rows updated.
SQL> rollback;
Rollback complete.
how ?
19

we remember stuff
20

SQL> update EMP
2 set SAL = SAL * 1.10
3 /
undo header
smith $1,0001
block 2754
jones $9002
brown $1,5003
wells $2,0004
wilson $1,0005
block 2754, row 1,
sal $1000
block 2754, row 2,
sal $900
block 2754, row 3,
sal $1500
block 2754, row 4,
sal $2000
uba 5
5
$1,100
$990
$1,650
$2,200
uba 5.1uba 5.2

SQL> rollback;
22

SQL> rollback;
undo header
smith $1,0001
block 2754
jones $9002
brown $1,5003
wells $2,0004
wilson $1,0005
block 2754, row 1,
sal $1000
block 2754, row 2,
sal $900
block 2754, row 3,
sal $1500
block 2754, row 4,
sal $2000
uba 5
5
$1,100
$990
$1,650
$2,200
uba 5.1uba 5.2

we can use this stuff for queries!
(Oracle version 4)
24

read consistency
25

select * from emp
where hiredate > '01/01/2004'
update emp set …
where empno = 1234;
Block 3217
"I need block 3217…
… as it was at 9:00"
9:00
9:03
9:05
session 1 session 2
...and time = scn

system change number
27

Session 1
Request
Block 3217,
SCN 4567192
Block 3217,
SCN 4567234
"ABC" Block 3217,
SCN 4567003,
change ABC => XYZ
undo segment block(s)
No good..too new
take a copy of the block
Locate
apply undo
Block 3217,
SCN 4567234
"ABC"
Block 3217,
SCN 4567234
"ABC"
Block 3217,
SCN 4567003
"XYZ"
Block 3217,
SCN 4567003
"XYZ"
Session 2
update emp
set ename = "ABC"
where empno = 1234;
commit;
Done !
28

every query = locked at a SCN
29

30
go back even further....

flashback query = choose SCN
31

v9
32

SQL> select * from DEPT;
DEPTNO DNAME LOC
---------- -------------- -------------
10 UNKNOWN NEW YORK
20 UNKNOWN DALLAS
30 UNKNOWN CHICAGO
40 UNKNOWN BOSTON
33

SQL> select * from DEPT AS OF SCN 995401;
DEPTNO DNAME LOC
---------- -------------- -------------
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON
34

a little less geeky
35

SQL> select * from DEPT
2 AS OF TIMESTAMP systimestamp -
3 interval '20:00' minute to second;
DEPTNO DNAME LOC
---------- -------------- -------------
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON
36

smon_scn_time
37

smon_scn_time ???
38

obsolete*
39
more later on this

SQL> select TIMESTAMP_TO_SCN(systimestamp) from DUAL;
TIMESTAMP_TO_SCN(SYSTIMESTAMP)
------------------------------
998332
40

SQL> select SCN_TO_TIMESTAMP(998314) from DUAL;
SCN_TO_TIMESTAMP(998314)
-----------------------------------------------
25-FEB-19 09.12.48.000000000 PM
41

3 seconds
42

SQL> select scn_to_timestamp(2409511-rownum)
2 from dual
3 connect by level <= 50;
SCN_TO_TIMESTAMP(2409511-ROWNUM)
---------------------------------------------
28-FEB-19 05.47.47.000000000 PM
28-FEB-19 05.47.47.000000000 PM
28-FEB-19 05.47.44.000000000 PM
28-FEB-19 05.47.41.000000000 PM
28-FEB-19 05.47.37.000000000 PM
28-FEB-19 05.47.34.000000000 PM
28-FEB-19 05.47.31.000000000 PM
28-FEB-19 05.47.28.000000000 PM
28-FEB-19 05.47.25.000000000 PM
43

use in "normal" queries
44

SQL> select e.empno, e.ename, d.dname
2 from emp e,
3 dept AS OF TIMESTAMP '23-FEB-19 11.51.02 PM' d
3 where d.deptno = e.deptno;
EMPNO ENAME DNAME
---------- ---------- --------------
7782 CLARK "PREVIOUS NAME"
7839 KING "PREVIOUS NAME"
7934 MILLER "PREVIOUS NAME"
7566 JONES RESEARCH
7902 FORD RESEARCH
7876 ADAMS RESEARCH
7369 SMITH RESEARCH
7788 SCOTT RESEARCH
45

"What's in it for me?"
46

1) unit testing
47

SQL> select case
2 when d1.deptno is null then 'DELETE'
3 when d2.deptno is null then 'INSERT'
4 end action,
5 d1.deptno, d2.deptno, d1.dname, d1.loc
6 from DEPT d1 full outer join
7 DEPT AS OF TIMESTAMP '23-FEB-19 11.51.02 PM' d2
8 on d1.deptno = d2.deptno;
ACTION DEPTNO DEPTNO DNAME LOC
------ ---------- ---------- -------------- ----------
10 10 ACCOUNTING NEW YORK
20 20 RESEARCH DALLAS
30 30 SALES CHICAGO
DELETE 40
INSERT 50 MARKETING PERTH
48

2) not just your data
49

SQL> drop procedure debug_msg;
Procedure dropped.
SQL> connect / as sysdba
Connected.
SQL> select text
2 from dba_source
3 as of timestamp systimestamp - interval '5' minute
4 where name='DEBUG_MSG' order by line;
TEXT
---------------------------------------------------------------------
procedure debug_msg(m varchar2) is
begin
dbms_output.put_line(m);
dbms_application_info.set_client_info(m);
end;
5 rows selected.
50

3) functional diagnosis
51

DEPTNO DNAME LOC
---------- -------------- -------------
10 UNKNOWN NEW YORK
SQL> select * from DEPT
2 as of TIMESTAMP SYSTIMESTAMP -
3 INTERVAL '20:00' MINUTE TO SECOND;
DEPTNO DNAME LOC
---------- -------------- -------------
1 change ?
10 changes ?

flashback row versions
53

SQL> SELECT deptno, dname
2 FROM dept
3 VERSIONS BETWEEN
4 TIMESTAMP SYSTIMESTAMP –
5 INTERVAL '20:00' MINUTE TO SECOND
6 AND SYSTIMESTAMP
7 WHERE deptno = 10;
DEPTNO DNAME
---------- --------------
10 ACCOUNTING
10 MONEY GRABBERS
10 FINANCE
10 BEAN COUNTERS
10 UNKNOWN
1 row
5 versions
54

versions_starttime
versions_startscn
versions_endtime
versions_endscn
versions_xid
versions_operation
55

SQL> SELECT deptno, dname,
2 VERSIONS_STARTTIME
3 ,VERSIONS_XID
4 ,VERSIONS_OPERATION
5 FROM dept
6 VERSIONS BETWEEN
7 TIMESTAMP SYSTIMESTAMP - INTERVAL '20:00' MINUTE TO SECOND
8 AND SYSTIMESTAMP
9 WHERE deptno = 10;
DEPTNO DNAME VERSIONS_STARTTIME VERSIONS_XID V
---------- -------------- ------------------------ ---------------- -
10 UNKNOWN 03-SEP-18 11.53.45 PM 0200100060040000 U
10 MONEY GRABBERS 03-SEP-18 11.53.36 PM 0600050065040000 U
10 FINANCE 03-SEP-18 11.53.24 PM 09000D001D050000 U
10 BEAN COUNTERS 03-SEP-18 11.53.12 PM 01001A00EA030000 U
10 ACCOUNTING
56

get the lot ...
57

SQL> SELECT deptno, dname,
2 VERSIONS_STARTTIME
3 ,VERSIONS_XID
4 ,VERSIONS_OPERATION
5 FROM dept VERSIONS BETWEEN SCN MINVALUE AND MAXVALUE;
DEPTNO DNAME VERSIONS_STARTTIME VERSIONS_XID V
---------- -------------- ------------------------ ---------------- -
50 UNKNOWN 03-SEP-18 11.08.15 PM 04000700EA030000 U
30 UNKNOWN 03-SEP-18 11.08.15 PM 04000700EA030000 U
20 NERDS 03-SEP-18 11.07.57 PM 090016001D050000 U
20 R&D 03-SEP-18 11.07.48 PM 05000B0074040000 U
...

grant flashback to ...
59

session level
60

dbms_flashback.enable_at_time(systimestamp-1);
61

SQL> exec dbms_flashback.enable_at_time(
systimestamp-5/86400)
PL/SQL procedure successfully completed.
SQL> insert into T values (1);
ERROR at line 1:
ORA-08182:
operation not supported while in Flashback mode
62

SQL> exec dbms_flashback.disable;
ERROR at line 1:
ORA-08184: attempting to re-enable Flashback while in Flashback
63

just how far ?
64

undo_retention
65

SQL> show parameter undo_retention
NAME TYPE VALUE
------------------------------ ----------- --------
undo_retention integer 900
66
~

SQL> desc v$undostat
Name Null? Type
----------------------------- -------- ----------------
BEGIN_TIME DATE
END_TIME DATE
...
...
TUNED_UNDORETENTION NUMBER
CON_ID NUMBER
67

much much further

"no" spanning DDL
69
better each version

rewind the data, not time
70
charactersets,
NLS etc

flashback
transaction
71

XID ?
73

SQL> desc V$TRANSACTION
Name Null? Type
----------------------------- -------- -------
XIDUSN NUMBER
XIDSLOT NUMBER
XIDSQN NUMBER
...
74

SQL> select XIDUSN, XIDSLOT, XIDSQN
2 from v$transaction
XIDUSN XIDSLOT XIDSQN
---------- ---------- ----------
1 31 674
SQL> select versions_xid from ...
VERSIONS_XID
-------------------
01 001F 00A202 0000
75

SQL> desc FLASHBACK_TRANSACTION_QUERY
Name Null? Type
----------------------- -------- --------------
XID RAW(8)
START_SCN NUMBER
START_TIMESTAMP DATE
COMMIT_SCN NUMBER
COMMIT_TIMESTAMP DATE
LOGON_USER VARCHAR2(30)
UNDO_CHANGE# NUMBER
OPERATION VARCHAR2(32)
TABLE_NAME VARCHAR2(256)
TABLE_OWNER VARCHAR2(32)
ROW_ID VARCHAR2(19)
UNDO_SQL VARCHAR2(4000)
76

SQL> select DNAME from dept
2 where deptno = 10;
DNAME
-------
FINANCE
SQL> select xid, undo_sql
2 from flashback_transaction_query
3 where xid = hextoraw('09000d001d050000');
XID UNDO_SQL
---------------- ------------------------------------
09000D001D050000 update "SCOTT"."DEPT"
set "DNAME" = 'BEAN COUNTERS'
where ROWID = 'AAAQ+hAAEAAAAAOAAA';
77

be careful
78

SQL> select text from dba_views
2 where view_name
3 = 'FLASHBACK_TRANSACTION_QUERY';
TEXT
------------------------------------------------
select
xid, start_scn, start_timestamp,
decode(commit_scn,
0, commit_scn,
281474976710655, NULL, commit_scn)
commit_scn, commit_timestamp,
logon_user, undo_change#, operation,
table_name, table_owner,
row_id, undo_sql
from SYS.X$KTUQQRY
79

do not query without predicates ...
80

do not forget hextoraw
81

3 where xid = hextoraw('09000d001d050000');
-----------------------------------------------------
| Id | Operation | Name |
-----------------------------------------------------
| 0 | SELECT STATEMENT | |
|* 1 | FIXED TABLE FIXED INDEX| X$KTUQQRY (ind:1) |
-----------------------------------------------------
83

3 where xid = '09000d001d050000';
--------------------------------------
| Id | Operation | Name |
--------------------------------------
| 0 | SELECT STATEMENT | |
| 1 | FIXED TABLE FULL| X$KTUQQRY |
--------------------------------------
84

UNDO_SQL
85

rollback committed transaction
86

87

three words
88

delete
uh-oh...
commit

90

undo a committed transaction
91

92

SQL> BEGIN
2 DBMS_FLASHBACK.TRANSACTION_BACKOUT(
3 numtxns=>1,
4 xids=>sys.xid_array('09000D001D050000')
5 );
6 END;
7 /
BEGIN
*
ERROR at line 1:
ORA-55510: Mining could not start
ORA-06512: at "SYS.DBMS_FLASHBACK", line 37
ORA-06512: at "SYS.DBMS_FLASHBACK", line 70
ORA-06512: at line 2
'09000D001D050000'
93

94

SQL> ALTER DATABASE ADD
2 SUPPLEMENTAL LOG DATA (PRIMARY KEY) COLUMNS;
Database altered.
95

SQL> delete from DEPT
2 where DEPTNO = 10;
1 row deleted.
SQL> commit;
Commit complete.
SQL> SELECT VERSIONS_XID
2 FROM dept
3 VERSIONS BETWEEN SCN MINVALUE AND MAXVALUE;
VERSIONS_XID
----------------
080017006C040000
96

SQL> BEGIN
2 DBMS_FLASHBACK.TRANSACTION_BACKOUT(
3 numtxns=>1,
4 xids=>sys.xid_array('080017006C040000')
5 );
6 END;
7 /
DEPTNO DNAME LOC
---------- -------------- ----------
20 RESEARCH DALLAS
30 SALES CHICAGO
50 MARKETING PERTH
40 HR US
97

KEEP CALM
AND
DON'T PANIC

SQL> SELECT COMPENSATING_XID
2 FROM DBA_FLASHBACK_TXN_STATE
3 WHERE xid = '080017006C040000';
COMPENSATING_XID
----------------
03001C0072040000
99

SQL> SELECT xid_report
2 FROM DBA_FLASHBACK_TXN_REPORT
3 WHERE compensating_xid = '03001C0072040000';
XID_REPORT
--------------------------------------------------------
<COMP_XID_REPORT XID="03001C0072040000">
<TRANSACTION XID="080017006C040000">
<UNDO_SQL>
<USQL exec="yes">
insert into "SCOTT"."DEPT"("DEPTNO","DNAME","LOC")
values ('10','ACCOUNTING','NEW YORK')
</USQL>
</UNDO_SQL>
</TRANSACTION>
<EXECUTED_UNDO_SQL>
<EXEC_USQL>
insert into "SCOTT"."DEPT"("DEPTNO","DNAME","LOC")
values ('10','ACCOUNTING','NEW YORK')
</EXEC_USQL>
</EXECUTED_UNDO_SQL>
</COMP_XID_REPORT> 100

SQL> commit;
Commit complete.
SQL> select * from dept;
DEPTNO DNAME LOC
---------- -------------- ----------
20 RESEARCH DALLAS
30 SALES CHICAGO
50 MARKETING PERTH
40 HR US
101

some typical restrictions
102
ddl, old lobs, xml

flashback
drop
103

105

three words
two
106

drop
uh-oh...

108

SQL> desc EMP
ERROR:
ORA-04043: object EMP does not exist
109

hard
place
You are here

"undrop"
111

not cool enough
112

flashback table to before drop
113

SQL> desc USER_RECYCLEBIN
Name Null? Type
----------------------------- -------- --------------------
OBJECT_NAME NOT NULL VARCHAR2(30)
ORIGINAL_NAME VARCHAR2(32)
OPERATION VARCHAR2(9)
TYPE VARCHAR2(25)
TS_NAME VARCHAR2(30)
CREATETIME VARCHAR2(19)
DROPTIME VARCHAR2(19)
DROPSCN NUMBER
PARTITION_NAME VARCHAR2(32)
CAN_UNDROP VARCHAR2(3)
CAN_PURGE VARCHAR2(3)
RELATED NOT NULL NUMBER
BASE_OBJECT NOT NULL NUMBER
PURGE_OBJECT NOT NULL NUMBER
SPACE NUMBER
115

SQL> select OBJECT_NAME, ORIGINAL_NAME,
2 CAN_UNDROP, CAN_PURGE
3 from USER_RECYCLEBIN;
OBJECT_NAME ORIGINAL_NAME CAN CAN
-------------------------------- ------------------- --- ---
BIN$CmYCdNcITL6hp9l266nskA==$0 PK_EMP NO YES
BIN$b/W75+c/Q/CeFMBIK7cXfw==$0 EMP YES YES
116

SQL> show RECYCLEBIN
117

indexes / constraints / triggers
... all renamed

SQL> flashback table EMP to before drop;
Flashback complete.
119

SQL> flashback table EMP to before drop
2 rename to OLD_EMP;
Flashback complete.
120

indexes / constraints / triggers
... not renamed back

how long ?
122

1 second...
...10 years
123

SQL> PURGE RECYCLEBIN;
SQL> PURGE TABLE emp;
SQL> PURGE TABLE "BIN$xyWe0+q+SniItJ0pn/u54A==$0";
SQL> PURGE TABLESPACE user1;
SQL> PURGE INDEX "BIN$FTX34MN88J7==$0";
SQL> PURGE TABLESPACE user1 USER fred;
124

no untruncate
125

flashback
table
126

flashback table
128

SQL> FLASHBACK TABLE DEPT
2 TO TIMESTAMP TO_TIMESTAMP('2019-06-03 12:05:00')
129

"undrop"
130

131

repeatable tests without cleanup scripts
132

deletes modified rows since SCN
inserts fresh rows as of SCN
... busy

SQL> FLASHBACK TABLE DEPT
2 TO TIMESTAMP TO_TIMESTAMP('2019-06-03 12:05:00')
3 ENABLE TRIGGERS;
134

rowid's change
... enable row movement
135

indexes existence unaffected
136

single transaction
137
... multiple tables allowed

tables locked
138

R.I must still be valid
139

statistics unchanged
140

most DDL is a flashback boundary
141

SQL> flashback table DEPT to scn ...;
ORA-01466: unable to read data - table definition has changed
142

each release gets better
143

SQL> alter table DEPT add column XXX date;
SQL> desc DEPT
Name Null? Type
-------------------------- -------- --------------
DEPTNO NUMBER(2)
DNAME VARCHAR2(14)
LOC VARCHAR2(13)
XXX DATE
144

ORA-08183: Flashback cannot be enabled in the middle
of a transaction
145

flashback
database
146

flashback database
149

Copyright © 2018, Oracle and/or its affiliates. All rights reserved. |
AUTHORISED
DATABASE
ADMINSTRATORS
ONLY !

SQL> alter database flashback on;
Database altered.
151

152
data
changes
"new" blocks
to disk
changes
to disk
"old" blocks
to disk
redo fbdadbwr

SQL> FLASHBACK DATABASE TO '2:05PM'
153

SQL> create restore point OK_SO_FAR;
...
SQL> flashback database to restore point OK_SO_FAR;
154

what does it cost ?
155

SQL> desc V$FLASHBACK_DATABASE_STAT
Name Null? Type
----------------------------- -------- ---------
BEGIN_TIME DATE
END_TIME DATE
FLASHBACK_DATA NUMBER
DB_DATA NUMBER
REDO_DATA NUMBER
ESTIMATED_FLASHBACK_SIZE NUMBER
156

a good compromise
157

guaranteed restore points
158

flashback logging "optional"
159

less aggressive
160

161

1) safer deployment
162

scenario: "My New Application"
163

9:00
9:40
9:45 SQL> FLASHBACK DATABASE...
164
SQL> alter table ACCOUNTS ...

2) repeatable end to end testing
165

166

12.2+
167

flashback pluggable database
168

3) production data for developers
169

"hidden" example
170

Data Guard
171

172
5:00am
11:30pm
standby recovery
convert to snapshot
revert to physical

flashback
data archive
173

less flashback, more archive
174

SQL> CREATE FLASHBACK ARCHIVE longterm
2 TABLESPACE space_for_archive
3 RETENTION 1 YEAR;
Flashback archive created.
175

SQL> ALTER TABLE EMP FLASHBACK ARCHIVE LONGTERM;
Table altered.
[lots of DML on EMP]
176

SQL> select * from EMP;
--------------------------------------------------
| Id | Operation | Name | Rows | Bytes |
--------------------------------------------------
| 0 | SELECT STATEMENT | | 14 | 518 |
| 1 | TABLE ACCESS FULL| EMP | 14 | 518 |
--------------------------------------------------
177

SQL> select * from EMP
2 AS OF TIMESTAMP SYSDATE-1/24;
--------------------------------------------------
| Id | Operation | Name | Rows | Bytes |
--------------------------------------------------
| 0 | SELECT STATEMENT | | 14 | 518 |
| 1 | TABLE ACCESS FULL| EMP | 14 | 518 |
--------------------------------------------------
178

3 days later...
179

SQL> select * from EMP
2 AS OF TIMESTAMP SYSDATE-3;
-----------------------------------------------------------------
| Id | Operation | Name | Rows |
-----------------------------------------------------------------
| 0 | SELECT STATEMENT | | 446 |
| 1 | VIEW | | 446 |
| 2 | UNION-ALL | | |
|* 3 | FILTER | | |
| 4 | PARTITION RANGE ITERATOR| | 445 |
|* 5 | TABLE ACCESS FULL | SYS_FBA_HIST_69539 | 445 |
|* 6 | FILTER | | |
|* 7 | HASH JOIN OUTER | | 1 |
|* 8 | TABLE ACCESS FULL | EMP | 1 |
|* 9 | TABLE ACCESS FULL | SYS_FBA_TCRV_69539 | 14 |
------------------------------------------------------------------180

SQL> select table_name
2 from user_tables
3 /
TABLE_NAME
---------------------------
SYS_FBA_HIST_71036
SYS_FBA_TCRV_71036
SYS_FBA_DDL_COLMAP_71036
EMP
181

182
note

183
"The table does not use any of these
Flashback Data Archive reserved words
as column names:
• STARTSCN
• ENDSCN
• RID
• XID
• OP
• OPERATION"

184

"I don't care what EMP looked
like last March..."
185

186
why talk about it ?

187
SQL> select * from EMP AS OF "JUNE";
SQL> select * from EMP AS OF "MARCH";
SQL> select * from EMP AS OF "2pm Wednesday";
SQL> select * from EMP AS OF etc etc etc

188
every historical version...

189
... of every row

190
sound familiar ?

191
audit history

192
we've all done it

193
SQL> desc T
Name Null? Type
------------------------ -------- -------------
OWNER NOT NULL VARCHAR2(30)
SQL> desc T_AUDIT
Name Null? Type
------------------------ -------- --------------
AUDIT_DATE DATE
AUDIT_ACTION CHAR(1)
OWNER NOT NULL VARCHAR2(30)

194
SQL> create or replace
2 trigger AUDIT_TRG
3 after insert or update or delete on T
4 for each row
5 declare
6 v_action varchar2(1) := case when updating
7 then 'U' when deleting then 'D' else 'I' end;
8 begin
9 if updating or inserting then
10 insert into T_AUDIT
11 values (sysdate
12 ,v_action
13 ,:new.owner
14 ,:new.object_name);
15 else
16 insert into T_AUDIT
17 values (sysdate
18 ,v_action
19 ,:old.owner
20 ,:old.object_name);
21 end if;
22 end;

195
works but slow...

196
SQL> insert into T
2 select owner, object_name
3 from all_objects
4 where rownum <= 10000;
10000 rows created.
insert into T select owner, object_name
from all_objects where rownum <= 10000
call count cpu elapsed disk query current rows
------- ------ ------- ---------- -------- --------- ---------- ----------
Parse 1 0.01 0.00 0 0 0 0
Execute 1 3.10 3.05 88 123 10642 10000
Fetch 0 0.00 0.00 0 0 0 0
------- ------ ------- ---------- -------- --------- ---------- ----------
total 2 3.12 3.06 88 123 10642 10000
INSERT INTO T_AUDIT
VALUES (SYSDATE ,:B3 ,:B1 ,:B2 )
call count cpu elapsed disk query current rows
------- ------ ------- ---------- -------- --------- ---------- ----------
Parse 1 0.00 0.00 0 0 0 0
Execute 10000 0.79 0.97 2 109 10845 10000
Fetch 0 0.00 0.00 0 0 0 0
------- ------ ------- ---------- -------- --------- ---------- ----------
total 10001 0.79 0.97 2 109 10845 10000

a better, faster, robust version ...
197

198

SQL> select empno, ename, job, sal, comm,
2 nvl(VERSIONS_STARTTIME,LAST_MOD) TS
3 ,nvl(VERSIONS_OPERATION,'I') op
4 from EMP
5 versions between timestamp
6 timestamp '2019-02-11 20:12:00' and systimestamp
7 order by empno, ts;
EMPNO ENAME JOB SAL COMM TS O
---------- ---------- --------- ---------- ---------- ------------ -
7369 SMITH CLERK 806 08.10.51 PM I
7369 SMITH SALES 8060 1000 08.12.10 PM U
7499 ALLEN SALESMAN 1606 300000000 08.10.51 PM I
7521 WARD SALESMAN 1256 500000000 08.10.51 PM I
7566 JONES MANAGER 2981 08.10.51 PM I
...
7900 JAMES CLERK 956 08.10.51 PM I
7902 FORD ANALYST 3006 08.10.51 PM I
7934 MILLER CLERK 1306 08.10.51 PM I
7934 MILLER CLERK 1306 08.12.10 PM D
199

so why didn't we ?
200

reason 1
201

"yeah...but who ? where ? how ?"
202

SQL> alter table EMP add UPDATED_BY varchar2(10);
Table altered.
SQL> alter table EMP add UPDATED_PGM varchar2(10);
Table altered.
[etc]
203

reason 2
204

separately licensed
206

12c+ ... more options
207

1) context extension
208

SQL> begin
2 dbms_flashback_archive.set_context_level(
3 level=> 'ALL');
4 end;
209

SQL> update EMP
2 set sal = sal*10
3 where empno = 7499;
1 row updated.
SQL> commit;
210

SQL> select XID from SYS_FBA_HIST_510592;
XID
----------------
09000B00C7080000
211

SQL> set serverout on
SQL> begin
2 dbms_output.put_line(
3 dbms_flashback_archive.get_sys_context (
4 '09000B00C7080000', 'USERENV', 'SESSION_USER'));
5
8 '09000B00C7080000', 'USERENV', 'HOST'));
9
12 '09000B00C7080000', 'USERENV', 'MODULE'));
13 end;
14 /
SCOTT
WORKGROUPXPS
SQL*Plus
212

...and a few other things :-)
213

SQL> desc SYS.SYS_FBA_CONTEXT_AUD
Name Null? Type
------------------------- -------- ------------------
XID RAW(8)
ACTION VARCHAR2(256)
AUTHENTICATED_IDENTITY VARCHAR2(256)
CLIENT_IDENTIFIER VARCHAR2(256)
CLIENT_INFO VARCHAR2(256)
CURRENT_EDITION_NAME VARCHAR2(256)
CURRENT_SCHEMA VARCHAR2(256)
CURRENT_USER VARCHAR2(256)
DATABASE_ROLE VARCHAR2(256)
DB_NAME VARCHAR2(256)
GLOBAL_UID VARCHAR2(256)
HOST VARCHAR2(256)
IDENTIFICATION_TYPE VARCHAR2(256)
INSTANCE_NAME VARCHAR2(256)
IP_ADDRESS VARCHAR2(256)
MODULE VARCHAR2(256) 214

SQL> @pt "select * from SYS.SYS_FBA_CONTEXT_AUD
where xid = '09000B00C7080000'"
XID : 09000B00C7080000
AUTHENTICATED_IDENTITY : scott
CLIENT_IDENTIFIER :
CLIENT_INFO :
CURRENT_EDITION_NAME : ORA$BASE
CURRENT_SCHEMA : SYS
CURRENT_USER : SYS
DATABASE_ROLE : PRIMARY
DB_NAME : np12
HOST : WORKGROUPXPS
IDENTIFICATION_TYPE : LOCAL
INSTANCE_NAME : np12
MODULE : SQL*Plus
OS_USER : xpshamcdc
SERVER_HOST : xps
...
215

SQL> select empno, ename, job, sal, comm,
2 VERSIONS_XID
3 from EMP
5 timestamp '2019-02-11 20:12:00' and systimestamp
6 order by empno;
EMPNO ENAME JOB SAL COMM VERSIONS_XID
---------- ---------- --------- ---------- ---------- ----------------
7369 SMITH CLERK 806
7369 SMITH SALES 8060 1000 09001C00E04A0000
7499 ALLEN CLERK 16060 300000000 0A000A0024080000
7499 ALLEN SALESMAN 16060 300000000 09000B00C7080000
7499 ALLEN SALESMAN 1606 300000000
7521 WARD SALESMAN 1256 500000000
216

SQL> select ...
2 from
3 ( select
4 empno, ename, job,
5 sal, comm, VERSIONS_XID
6 from EMP
8 timestamp '2019-02-11 20:12:00' and
9 systimestamp
10 ) e, SYS.SYS_FBA_CONTEXT_AUD a
11 where e.VERSIONS_XID = a.XID;
217

2) price...
218

flashback data archive is now …
219

220

not a typo
221

basic versus advanced
222

choose your cost
compression
223

so think about FDA
224

secure
read only
225

efficient
fdba
226

all of your history...
227

... all of your audit
228

"Where were you in 2004 ?!?!?"
229

dbms_flashback_archive.import_history
230

be careful ... silent errors
231

SQL> ALTER TABLE EMP FLASHBACK ARCHIVE LONGTERM;
Table altered.
Flashback Archive:
Error ORA-1950 in SQL create table "SCOTT".SYS_FBA_DDL_COLMAP_91938
(STARTSCN NUMBER, ENDSCN NUMBER...
Flashback Archive:
Error ORA-942 in SQL insert into "SCOTT".SYS_FBA_DDL_COLMAP_91938
(ENDSCN, COLUMN_NAME, TYPE, ...
232

back to smon_scn_time
233

CREATE TABLE "SYS"."SMON_SCN_TIME"
( "THREAD" NUMBER,
"TIME_MP" NUMBER,
"TIME_DP" DATE,
"SCN_WRP" NUMBER,
"SCN_BAS" NUMBER,
"NUM_MAPPINGS" NUMBER,
"TIM_SCN_MAP" RAW(1200),
"SCN" NUMBER DEFAULT 0,
"ORIG_THREAD" NUMBER DEFAULT 0
) CLUSTER "SYS"."SMON_SCN_TO_TIME_AUX" ("THREAD")
234
2^16 = ~3.5 years

"Recreate SMON_SCN_TIME as non-clustered table"
Doc ID 2389804.1
235

other stuff
236

Session 1
Request
Block 3217,
SCN 4567192
Block 3217,
SCN 4567234
"ABC" Block 3217,
SCN 4567003,
change ABC => XYZ
undo segment block(s)
No good..too new
take a copy of the block
Locate
apply undo
Block 3217,
SCN 4567234
"ABC"
Block 3217,
SCN 4567234
"ABC"
Block 3217,
SCN 4567003
"XYZ"
Block 3217,
SCN 4567003
"XYZ"
Session 2
update emp
set ename = "ABC"
where empno = 1234;
commit;
Done !
237

ORA_ROWSCN
238

SQL> SELECT ORA_ROWSCN,empno,ename,sal
2 FROM emp;
ORA_ROWSCN EMPNO ENAME SAL
---------- ---------- ---------- ----------
1357038 7369 SMITH 800
1357038 7499 ALLEN 1600
1357038 7521 WARD 1250
1357038 7566 JONES 2975
1357038 7654 MARTIN 1250
1357038 7698 BLAKE 2850
1357038 7782 CLARK 2450
1357038 7788 SCOTT 3000
1357038 7839 KING 5000
1357038 7844 TURNER 1500
1357038 7876 ADAMS 1100
1357038 7900 JAMES 950
1357038 7902 FORD 3000
1357038 7934 MILLER 1300
239

block level SCN
240

SQL> UPDATE emp SET sal = 9999
2 WHERE empno = 7369;
2 FROM emp;
---------- ---------- ---------- ----------
1357484 7369 SMITH 9999
1357484 7499 ALLEN 1600
1357484 7521 WARD 1250
1357484 7566 JONES 2975
1357484 7654 MARTIN 1250
1357484 7698 BLAKE 2850
1357484 7782 CLARK 2450
1357484 7788 SCOTT 3000
1357484 7839 KING 5000
1357484 7844 TURNER 1500
1357484 7876 ADAMS 1100
1357484 7900 JAMES 950
1357484 7902 FORD 3000
1357484 7934 MILLER 1300 241

SQL> CREATE TABLE newemp ROWDEPENDENCIES
2 AS SELECT * FROM emp;
242

SQL> UPDATE newemp SET sal = 9999
2 WHERE empno = 7369
2 FROM newemp;
---------- ---------- ---------- ----------
1357558 7369 SMITH 9999
1357545 7499 ALLEN 1600
1357545 7521 WARD 1250
1357545 7566 JONES 2975
1357545 7654 MARTIN 1250
1357545 7698 BLAKE 2850
1357545 7782 CLARK 2450
1357545 7788 SCOTT 3000
1357545 7839 KING 5000
1357545 7844 TURNER 1500
1357545 7876 ADAMS 1100
1357545 7900 JAMES 950
1357545 7902 FORD 3000
1357545 7934 MILLER 1300
243

SQL> select ORA_ROWSCN,
SCN_TO_TIMESTAMP(ORA_ROWSCN)
2 FROM emp
3 WHERE ...
244

wrap up
245

all included in EE
247

all cool for modern development
248

That's a wrap!
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twitter bit.ly/twitter-connor

Kscope19 - Flashback: Good for Developers as well as DBAs

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