SNA/ora_rowscn issues

Similar Questions

• ORA_ROWSCN Timestamp

  Hello
  
  I was walking in this ORA_ROWSCN virtual and found a STRANGE thing that triggers me to raise this issue.
  

  PRAZY@11gR1> select scn_to_timestamp(ora_rowscn) LAST_DML,rowid,ename from tests;
  
  LAST_DML                                 ROWID              ENAME
  ---------------------------------------- ------------------ ---------
  05-MAR-10 01.42.25.000000000 PM          AAAWeXAAEAAAAGFAAA TEST7
  05-MAR-10 01.42.25.000000000 PM          AAAWeXAAEAAAAGFAAB 39:53
  05-MAR-10 01.42.25.000000000 PM          AAAWeXAAEAAAAGFAAC 40:08
  05-MAR-10 11.15.37.000000000 AM          AAAWeXAAEAAAAGGAAA TEST5
  05-MAR-10 11.15.37.000000000 AM          AAAWeXAAEAAAAGGAAB TEST6
  05-MAR-10 10.14.15.000000000 AM          AAAWeXAAEAAAAGHAAA TEST1
  05-MAR-10 10.14.15.000000000 AM          AAAWeXAAEAAAAGHAAB TEST2
  05-MAR-10 10.14.15.000000000 AM          AAAWeXAAEAAAAGHAAC TEST3
  05-MAR-10 10.14.15.000000000 AM          AAAWeXAAEAAAAGHAAD TEST4
  
  9 rows selected.
  
  Elapsed: 00:00:00.00

  In the table above, the TEST1 to TEST4 data was inserted approximately at the same time and after an hour, I inserted another 3 records TEST5 - TEST7 and finally a few minutes back I made an another two inserts '39:53' and '40:08 '.
  
  While the ORA_ROWSCN verification, to my great surprise, TEST7 and other two newly created lines were projected as recently updated, but my only inserts '39:53' and '40:08' should be the last DML and TEST7 should go with timestamp TEST5 and TEST6.
  
  And I did a cross-checking of rowid and found 'TEST7', '39:53' and '40:08' share the rowid of the same block number 'AAAAGF '. and TEST5, TEST6 block number is different and even with the rest.
  
  My question is, does perform DML on a table will change the SNA the last DML and lines sharing the same number of block? If not how if functions?
  
  Kind regards
  Prazy
  
  Published by: PrazY on March 5, 2010 14:11
  Changed to virtual ;)

  PrazY wrote:
  Anurag thanks, I received another stupid question, is possible that the same block is shared by another table?

  Lets say, in block 2, there is another line of another table with id "AAAWeXAAEAAAAGGAAC" of the line. the RCS also change to that rank while from TEST5 on table TESTS and even if we did not all DML on this new line-specific table? This situation will even be possible?

  Kind regards
  Prazy

  Hi Prazzy,

  If you know the architecture of Oracle Oracle stores then more than 1 table in tablespaces (and each table can extend over several datafile)
  But each table (or segment) consists of the Group of extensions.
  Each scope is a block of States.map of the blocks of the BONE and is not shared between multiple tables. This is why a particular measure cannot contain more lines of 1table. And given that data blocks represent the scopes a particular data block cannot contain the data in the table of multiples, but just a single table.

  The foregoing does not hold true that for the table cluster.

  Concerning
  Anurag

• RMAN-05556: not all data files have backups can be picked up at SNA

  Dear all,

  By RMAN cloning in 11.2.0.3 database with ebs 11i.

  We get below error.

  RMAN-00571: ===========================================================

  RMAN-00569: = ERROR MESSAGE STACK FOLLOWS =.

  RMAN-00571: ===========================================================

  RMAN-03002: failure of Db in dual at 03/07/2015 15:36:20

  RMAN-05501: abandonment of duplicate target database

  RMAN-05556: not all data files have backups can be recovered on SNA 15901715

  991

  RMAN-03015: an error has occurred in the script stored memory Script

  RMAN-06026: some targets not found - abandonment of restoration

  RMAN-06100: no channel to restore a backup or a copy of the data file 94

  RMAN-06100: no channel to restore a backup or a copy of the data file 93

  RMAN-06100: no channel to restore a backup or a copy of the data file 92

  RMAN-06100: no channel to restore a backup or a copy of the data file 91

  RMAN-06100: no channel to restore a backup or a copy of the data file 90

  RMAN-06100: no channel to restore a backup or a copy of the data file 89

  RMAN-06100: no channel to restore a backup or a copy of the data file 88

  RMAN-06100: no channel to restore a backup or a copy of the data file 87

  RMAN-06100: no channel to restore a backup or a copy of the data file 86

  RMAN-06100: no channel to restore a backup or a copy of the data file 85

  RMAN-06100: no channel to restore a backup or a copy of the data file 84

  RMAN-06100: no channel to restore a backup or a copy of the data file 83

  RMAN-06100: no channel to restore a backup or a copy of the data file 82

  RMAN-06100: no channel to restore a backup or a copy of the data file 81

  RMAN-06100: no channel to restore a backup or a copy of the data file 80

  RMAN-06100: no channel to restore a backup or a copy of the data file 79

  RMAN-06100: no channel to restore a backup or a copy of the data file 78

  RMAN-06100: no channel to restore a backup or a copy of the data file 77

  RMAN-06100: no channel to restore a backup or a copy of the data file 76

  RMAN-06100: no channel to restore a backup or a copy of the data file 75

  RMAN-06100: no channel to restore a backup or a copy of the data file 74

  RMAN-06100: no channel to restore a backup or a copy of the data file 73

  RMAN-06100: no channel to restore a backup or a copy of the data file 72

  RMAN-06100: no channel to restore a backup or a copy of the data file 71

  RMAN-06100: no channel to restore a backup or a copy of the data file 70

  RMAN-06100: no channel to restore a backup or a copy of the data file 69

  RMAN-06100: no channel to restore a backup or a copy of the data file 68

  RMAN-06100: no channel to restore a backup or a copy of the data file 67

  RMAN-06100: no channel to restore a backup or a copy of the data file 66

  RMAN-06100: no channel to restore a backup or a copy of the data file 65

  RMAN-06100: no channel to restore a backup or a copy of the data file 64

  RMAN-06100: no channel to restore a backup or a copy of the data file 63

  RMAN-06100: no channel to restore a backup or a copy of the data file 62

  RMAN-06100: no channel to restore a backup or a copy of the data file 61

  RMAN-06100: no channel to restore a backup or a copy of the data file 60

  RMAN-06100: no channel to restore a backup or a copy of the data file 59

  RMAN-06100: no channel to restore a backup or a copy of the data file 58

  RMAN-06100: no channel to restore a backup or a copy of the data file 57

  RMAN-06100: no channel to restore a backup or a copy of the data file 56

  RMAN-06100: no channel to restore a backup or a copy of the data file 55

  RMAN-06100: no channel to restore a backup or a copy of the data file 54

  RMAN-06100: no channel to restore a backup or a copy of the data file 53

  RMAN-06100: no channel to restore a backup or a copy of the data file 52

  RMAN-06100: no channel to restore a backup or a copy of the data file 51

  RMAN-06100: no channel to restore a backup or a copy of the data file 50

  RMAN-06100: no channel to restore a backup or a copy of the data file 49

  RMAN-06100: no channel to restore a backup or a copy of the data file 48

  RMAN-06100: no channel to restore a backup or a copy of the data file 47

  RMAN-06100: no channel to restore a backup or a copy of the data file 46

  RMAN-06100: no channel to restore a backup or a copy of the data file 45

  RMAN-06100: no channel to restore a backup or a copy of the data file 44

  RMAN-06100: no channel to restore a backup or a copy of the data file 43

  RMAN-06100: no channel to restore a backup or a copy of the data file 42

  RMAN-06100: no channel to restore a backup or a copy of the data file 41

  RMAN-06100: no channel to restore a backup or a copy of the data file 40

  RMAN-06100: no channel to restore a backup or a copy of the data file 39

  RMAN-06100: no channel to restore a backup or a copy of the data file 38

  RMAN-06100: no channel to restore a backup or a copy of the data file 37

  RMAN-06100: no channel to restore a backup or a copy of the data file 36

  RMAN-06100: no channel to restore a backup or a copy of the data file 35

  RMAN-06100: no channel to restore a backup or a copy of the data file 34

  RMAN-06100: no channel to restore a backup or a copy of the data file 33

  RMAN-06100: no channel to restore a backup or a copy of the data file 32

  RMAN-06100: no channel to restore a backup or a copy of the data file 31

  RMAN-06100: no channel to restore a backup or a copy of the data file 30

  RMAN-06100: no channel to restore a backup or a copy of the data file 29

  RMAN-06100: no channel to restore a backup or a copy of the data file 28

  RMAN-06100: no channel to restore a backup or a copy of the data file 27

  RMAN-06100: no channel to restore a backup or a copy of the data file 26

  RMAN-06100: no channel to restore a backup or a copy of the data file 25

  RMAN-06100: no channel to restore a backup or a copy of the data file 24

  RMAN-06100: no channel to restore a backup or a copy of the data file 23

  RMAN-06100: no channel to restore a backup or a copy of the data file 22

  RMAN-06100: no channel to restore a backup or a copy of the data file 21

  RMAN-06100: no channel to restore a backup or a copy of the data file 20

  RMAN-06100: no channel to restore a backup or a copy of the data file 19

  RMAN-06100: no channel to restore a backup or a copy of the data file 18

  RMAN-06100: no channel to restore a backup or a copy of the data file 17

  RMAN-06100: no channel to restore a backup or a copy of the data file 16

  RMAN-06100: no channel to restore a backup or a copy of the data file 15

  RMAN-06100: no channel to restore a backup or a copy of the data file 14

  RMAN-06100: no channel to restore a backup or a copy of the data file 13

  RMAN-06100: no channel to restore a backup or a copy of the data file 12

  RMAN-06100: no channel to restore a backup or a copy of the data file 11

  RMAN-06100: no channel to restore a backup or a copy of the data file 10

  RMAN-06100: no channel to restore a backup or a copy of the data file 9

  RMAN-06100: no channel to restore a backup or a copy of the data file 8

  RMAN-06100: no channel to restore a backup or a copy of the data file 7

  RMAN-06100: no channel to restore a backup or a copy of the data file 6

  RMAN-06100: no channel to restore a backup or a copy of the data file 5

  RMAN-06100: no channel to restore a backup or a copy of the data file 4

  RMAN-06100: no channel to restore a backup or a copy of the data file 3

  RMAN-06100: no channel to restore a backup or a copy of the data file 2

  RMAN-06100: no channel to restore a backup or a copy of the data file 1

  Concerning

  Villi Kumar

  Dear all,

  Solution:

  Location of the data file is not correct that we are mentioned in the file (init.ora) settings.

  Change the location of data file settings.

  Test the issue again.

  Concerning

  Villi Kumar

• High low SNA SNA

  Hi all

  A redo log file has the same "low RCS' as the 'high' of his previous log sequence SNA. This means that it again for the transaction secured by this SCN is reflected in both these log files?

  Kind regards

  Vinod

  When you view this information?

  v$ log_history a first_change # and next_change # for newspapers. Note that it is the NEXT issue of change, not LAST change number. The NEXT of a newspaper is the FIRST of the next newspaper.

• MAX (ORA_ROWSCN)

  SELECT MAX (ORA_ROWSCN) SNA TBL1

  UNION

  SELECT MAX (ORA_ROWSCN) IN THE TBL2

  UNION

  SELECT MAX (ORA_ROWSCN) IN TBL3

  This SQL gives me three values in a column YVERT. How to get the same values in different columns scn1, cns2, SCN3?

  Like this?

  select (select max(ora_rowscn) from tbl1) scn1
       , (select max(ora_rowscn) from tbl2) scn2
       , (select max(ora_rowscn) from tbl3) scn3
    from dual
  

• Session ORA_ROWSCN is linked?

  I was doing research to try to understand a bit more about the ORA_ROWSCN feature.  I hope someone can explain what I see.

  For my tests, I created the following table.

  CREATE TABLE TEST3

  (

  COL1 NUMBER,

  USERS VARCHAR2 (10) USER BY DEFAULT.

  USERS_SID NUMBER SYS_CONTEXT ('USERENV', 'SID') BY DEFAULT,

  TIME_STAMP DATE DEFAULT SYSDATE

  );

  I inserted lines in this table - I first connected as SYSTEM, reconnected as SYSTEM and then connected as CODY.  The first session created for the connection of the SYSTEM was SID 255 (as shown in the output).  The next session created for the connection of the SYSTEM was SID 367.  The next session created for the connection of CODY was 255 SID.  It was the same SID previously used by the connection of the SYSTEM.  Here is the table for which the RCS data.  What I found interesting is that when a change has been made for a given SID, all lines that have been previously inserted or updated so that SID got the new SNA - not only the new lines.  You can see in the outputs field time_stamp including the moment the file is actually spent.

  My question is: why each line previously updated by a given session becomes a new SNA for every change of this session?  For example, in the output, you can see that the last record was inserted at 11:52 and the first record inserted for the session (255) was at 11:32.  However for all records with SID 255 CHN has been updated with the last change.

  

  No - ORA_ROWSCN is NOT bound session.

  You marked this as ANSWER, but I want to make it clear that the statements you have posted is NOT correct. If fact, many of you statements are completely false or very misleading.

  What I found interesting is that when a change has been made for a given SID, all lines that have been previously inserted or updated so that SID got the new SNA - not only the new lines.

  No - not all rows get a new SNA. As others have stated that when the dependencies of line is not used ORA_ROWSCN is at the block level.

  Thus, all THE ROWS in a block will be ORA_ROWSCN even. If you change just ONE LINE then all of THE rows in this block will reflect the ORA_ROWSCN for the block. But the ORA_ROWSCN for other blocks/lines won't be altered 'all lines that have been previously inserted or updated' will NOT have the new ORA_ROWSCN - that will be possible only if these wors are in the same block as the last row being changed but will NOT happen if they are in another block.

  You can see in the outputs field time_stamp including the moment the file is actually spent.

  No - this TIME_STAMP column is populated with the help of SYSDATE so the value will be the SYSDATE value that existed at the time where the INSERT statement is executed.

  The ORA_ROWSCN value is determined at the time of the VALID transaction. Can be seconds, hours, or even days between the time of INSERTION and VALIDATION time.

  Also the function SCN_TO_TIMESTAMP is an APPROXIMATE value and may be shifted a few seconds of the actual time that the operation of SNA was made.

  http://docs.Oracle.com/CD/B28359_01/server.111/b28286/functions149.htm

  SCN_TO_TIMESTAMPtakes as an argument a number that corresponds to a system change number (SCN) and returns an approximate timestamp associated with the SNA. The returned value is of TIMESTAMP the data type. This function is useful when you want to know the time stamp associated with a SNA. For example, it can be used in conjunction with the ORA_ROWSCN virtual to associate a time stamp with the most recent change to a line.

  Notes:

  • The usual accuracy of the value of the result is 3 seconds.
  • The association between a SNA and a timestamp when the RCS is generated is known by the database for a limited period of time. This period is the maximum value of the undo retention period auto tuned, if the database is running in Automatic Undo Management mode, and the retention of flashback time all records in the database, but no less than 120 hours. The time for the association become obsolete only when the database is opened. An error is returned if the SCN specified for the argument SCN_TO_TIMESTAMP is too old.

  You can also have multiple statements within the same transaction. So you can insert 2 rows, and then a few seconds/minutes later insert a few more lines. These lines would TIME_STAMP values due to the use of SYSDATE, but would have to value ORA_ROWSCN EVEN when the TRANSACTION is committed.

  My question is: why each line previously updated by a given session becomes a new SNA for every change of this session?

  Is not - as you know by now.

  The only reason why you example seems to show that this is because all your lines are probably stored in the same block or you change at least one line in EACH block. Each previous row does NOT get a new SNA - only the preceding lines in the same block, modified by the new session (by ANY USER) will appear to get a new SNA.

  As I explained above it has NOTHING to do with what makes a session, or not do. It is ONLY related to a change in beiing in a block.

• ORA_ROWSCN continues to increase without any DML

  Hi Experts,
  
  I use ORA_ROWSCN in ETL for the incremental data capture.
  Problem is that the ORA_ROWSCN continue to increase for some table without any DML.
  Table have ROWDEPENDENCIES.
  There is no audit, trigger, or batch running on the tables.
  Database is 11.2.0.3 on Windows 64 bit OS.
  ETLs perform DML heavy overnight. During the day, max (ORA_ROWSCN) continues to rise for a few tables.
  
  I noticed that during the questioning of a few paintings, SCN_TO_TIMESTAMP (max (ORA_ROWSCN)) has shown the current timestamp.
  
  Can cause the "delayed block drain plug" this?
  If this is not the case, is it then any other bug cause or identified?
  Is there enough reliable ORA_ROWSCN?
  
  Thank you
  Santosh kumar

  Welcome to the forum!
  >
  I use ORA_ROWSCN in ETL for the incremental data capture.
  Problem is that the ORA_ROWSCN continue to increase for some table without any DML.
  Table have ROWDEPENDENCIES.
  There is no audit, trigger, or batch running on the tables.
  Database is 11.2.0.3 on Windows 64 bit OS.
  ETLs perform DML heavy overnight. During the day, max (ORA_ROWSCN) continues to rise for a few tables.

  I noticed that during the questioning of a few paintings, SCN_TO_TIMESTAMP (max (ORA_ROWSCN)) has shown the current timestamp.

  Can cause the "delayed block drain plug" this?
  If this is not the case, is it then any other bug cause or identified?
  Is there enough reliable ORA_ROWSCN?
  >
  Congrats on being one of the few to ask a question which is, as Arte Johnson (of Laugh-In fame) would say, "very interesting".

  Unfortunately for us, you have also provided your own answer! ;)

  Drain plug can cause that? Yes - one of the oddities of the drain plug delay block even with a table by using ROWDEPENDENCIES is that Oracle may not always determine the exact SCN and therefore can use slightly more high when finished.

  Reliable? Yes - ORA_ROWSCN is reliable enough. But, as you will see, you must force the Oracle to drain plug blocks before use ORA_ROWSCN to query the changes.

  The best discussion, which includes the code example, is on the site of challenge from PL/SQL to a fault, a year or two it is
  "Impact of the Serializable Transaction not seen by players (9622).
  http://PLSQL-challenge.blogspot.com/2012/01/rowdependencies-impact-not-seen-by.html

  Anyone with enough interest should read the entire article, long and many answers. You will find them VERY informative. I suggest you add this bookmark to your "Oracle Toolbox.

  I included only a short extract conclusions regarding your question here and the code example illustrating the it.
  >
  Smail:

  I wonder if the ROWDEPENDENCIES guarantees 100% accuracy
  ORA_ROWSCN for each line.
  As far as I understand it, it can still generate false positives, but much less, because each row has its own ORA_ROWSCN that is NOT affected if other lines in the block are updated or locked/jerks, but still can be slightly higher than that of true to the line itself when Oracle it cannot determine precisely when cleaning
  >
  And the answer with the code
  >
  _Nikotin:

  but maybe still slightly higher than that of true to the line itself when Oracle it cannot determine precisely when cleaning.

  Yes, here is the example of the impact of the delay block drain plug:

  drop table plch_test;
  drop table plch_test2;

  create table plch_test (number, varchar2 (100) tilte, number of val) rowdependencies;

  Start
  insert into plch_test values (1, 'creation and validation at level 1', 0);
  insert into plch_test values (2, 'to update and commit to step 2', 0);
  commit;
  end;
  /

  update the value val = 1 plch_test where a = 2;

  change the built-in system buffer_cache;

  commit;

  create table plch_test2 (number, varchar2 (100) tilte, number of val) rowdependencies;

  Start
  insert into plch_test2 values (3, 'create and commit to step 3', 0);
  insert into plch_test2 values (4, 'to update and commit 1e5 times in step 4', 0);
  commit;
  end;
  /

  Start
  because me in 1... loop 1E5
  Update plch_test2 the value val = val + 1 where a = 4;
  commit;
  end loop;
  end;
  /

  Select t.*, Yvert plch_test2 ora_rowscn t
  Union of all the
  Select t.*, plch_test ora_rowscn t
  order by SNA;

  After that, you can see that steps 2 and 3 are reversed in the query result:

  SQL > select t.*, Yvert plch_test2 ora_rowscn t
  2 Union all the
  3. Select t.*, plch_test ora_rowscn t
  4 order of SNA;

  A VAL TILTE SNA
  ---------- -------------------------------------------- ---------- ----------
  1. create and validation, to 1 0 1998971227 step
  3. create and validation, to step 3 0 1998971254
  2 update and validation, 2 1 1999009794 step
  4 update and commit times in step 4 100000 1999224125 1e5
  >
  You can see from the above result to the effect that you get

• I want to know when we issue statement truncate table in oracle.

  I want to know when we issue statement truncate table in oracle. No newspaper will be write in the redo log. But we can recover data using flashback or SNA. I want to know where the actually truncate table statement log is stored in the oracle database. Please explain to me in detail step by step.

  >
  I understand your SNA. But I want to know where the truncate statement stored log. But in the redo log, no entry for truncate.but I want to go which connect there is no market value back...
  >
  If you are still wondering after getting the answer so you don't "understand".

  You have received the reply above. Archive of flashback stores data.

  See the link provided above to CREATE an ARCHIVE of FLASHBACK in the doc of SQL language
  http://docs.Oracle.com/CD/E11882_01/server.112/e26088/statements_5010.htm
  >
  TABLESPACE clause

  Specify the table space where the data archived for this flashback data archive referring to be stored. You can specify that a tablespace with this clause. However, you can then add tablespaces to archive flashback with a statement ALTER FLASHBACK ARCHIVE database.
  >
  The data is moved to storage of archives and restored from there when you query for archive flashback.

• Cancel the stop and the SNA

  Are there YVERT + 1 from the current SNA if I said the judgment? I want to say oracle increment Yvert at the time of the judgment? Any link to answer her Yes/No Doc: Please? What is the difference of this behavior in different versions of Oracle?
  
  Thank you.

  user12050217 wrote:
  Thank you for your response. Can you please give me link documentation to enter more details. Is this behavior is the same everywhere in oracle versions please?

  No documentation that I am aware of deals with what happens to SCN to the judgment. The closest is http://docs.oracle.com/cd/E11882_01/server.112/e25789/startup.htm#sthref1645 and http://docs.oracle.com/cd/E11882_01/server.112/e25494/start003.htm#sthref430

  We know that a the judgment is a signal to stop any treatment and do not write anything else to all files. This was behavior since at least 6 of Oracle. (I have to dig my Oracle 5 manuals - memory becomes fragile on this far behind). So it makes sense that any SNA that may have been issued after the abandoned closure are potentially lost, because they will not have anywhere have been saved.

  If you want to check that, I encourage you to get out of your favorite debugger.

  No particular reason to want that level of detail?

• KEEP issues of IDENTITY

  Hello
  
  I'm trying to understand something about rolling of improvement of a transitional logical standby which seems to escape me.
  
  So one of the first steps is to convert the standby database to a logic (with KEEPING IDENTITY clause), start to upgrade and then run the catupgrd script. Meanwhile the eve does not apply to the primary again.
  
  I understand that clause to KEEP IDENTITY results in the logical standby to retain the same DBID and name as the primary database.
  
  Issues related to the:
  1. Why does KEEP IDENTITY? For example, what happens if the clause to KEEP IDENTITY was not used during the upgrade, and kept the day before it's own identity?
  2. IDENTITY of KEEPING a specific requirement for the upgrade process, or this clause can be used for other uses?
  3. this question is not specifically linked to 'KEEP the IDENTITY'. So, how is it possible that you can run catupgrd to upgrade the database pending and THEN start to receive again the primary? I know that in a physical standby, the system would balk because of different system SNA after the catupgrd don't let him make a successful recovery. If a logical standby ignore SCN? (Sorry, I know good physical Standby, but not enough on logical STANDBY for answering this question myself)
  
  Any response would be appreciated...
  
  Thank you.
  
  Rob

  Hello;

  The new clause to KEEP IDENTITY keeps the same DB_NAME and DBID as the primary database.

  This facilitates the later stage when you convert the transitional logical standby database to its original role pending physical.

  This follow the idea that a physical primary and Standby are of the same data in different roles.

  KEEP IDENTITY is new in Oracle 11 G.

  KEEP the IDENTITY is used for the conversion of a logical Standby, I don't believe it we used elsewhere.

  It is a small amount of information

  11g Dataguard new features. [443540.1 ID]

  This may answer the question 3:

  http://docs.Oracle.com/CD/E11882_01/server.112/e23633/upgrade.htm

  Upgrading and opening a physical Standby during the primary has failed during the upgrade [975614.1 ID]

  10g implemented at level rippled with logical Standby [ID 300479.1]

  http://docs.Oracle.com/CD/B28359_01/server.111/b28294/create_ls.htm

  Best regards

  mseberg

  Published by: mseberg on 5 March 2012 06:10

• Reading consistent (Datablock and SNA)

  Hi experts,
  
  When a SELECT statement is issued, SCN of the select query is determined. Then the blocks with higher YVERT are reconstructed from the RBS structure... is what I know uptill this point
  
  Now as I'm user01 according to the consistency of reading for the user model:
  
  I had an employee table in my database. I pulled a SNA update query (1005) and updated two blocks. So now view data
  I pulled a query select (YVERT is 1010) and all the blocks that are less then it will be then displayed for me blocks all present and updated data will be displayed.
  
  Now user02 started a session and he pulled a select statement on the same table and SNA was 1012
  One more time all the blocks with YVERT less then 1012 will appear so he will also receive an update of data? that is not possible because I have not committed my data...
  
  How to read the maintenance of uniformity?
  So, how does this work?
  
  Second thing my executed query: select query will make me blocks of database... How to select query will come from knowledge that this block is engaged or uncommittted?
  
  The thing is when I fire the select query is good that first it checks n difference YVERT and then it will check for the block if its committed or not? am I wrong?
  
  When I commit the commit THAT SNA will be updated to the data file and the control file that is recorded in the Redo Log?
  
  Thank you
  Philippe

  Kamy wrote:

  I spotted the answer what I wanteds.got my eaxact response in the book of concepts oracle 11.2 on page 181 para says:

  * Read consistency and Transaction tables the database also uses an operating table,
  calls a list of self-dealing (ITL), to determine if a transaction has been
  uncommitted when the database has begun to change the block. The header block of
  each block segment contains a transaction table.*

  But Sir, I had a doubt this operation and ITL table the two are from different tables?

  You have reason to doubt.
  For people who have known these things for a long time, the "operating table" is the name given to the structure in a segment undo header block to contain a list of recent transactions that have used this undo segment to store their files of cancellation.

  The 'list of self-dealing' is the name given to a structure that exists in each normal block of data (including the index) to contain a list of recent transactions that have modified this block. It was very stupid of the author of this page to decide to reuse the name of a structure as an alias for the other.

  Concerning
  Jonathan Lewis

• A SCN for the entire database and the different SNA for the data files?

  DB Version: 11 g
  
  I always thought that there is a unique SCN for the database as a whole.
  A quote from the link below as
  When a control point is completed, Oracle stores the RCS individually in the control for each data file file
  http://www.dbapool.com/articles/1029200701.html
  
  
  What does that mean? There is a SNA for the entire database, and there are individual SCN for each data files?

  Well, unfortunately, the article says more bad than good things. Or if I can't call them wrong, they are rather confusing and rather than clear things for the reader, its making them appear to look more confused.

  First things, YVERT is used for read consistency (CR) mechanism and the backbone of the notion of Multiversioning. The control point is the mechanism to help that recovery is decided. Contrary to what said article, not any kind of checkpoints update both the data file and the control file, and also, there is not a type of them as well. In addition, the article says that the LAST_CHECKPOOINT is set to NULL, while its actually set to the infinity since it is not possible to detect the moment when the database is opened, that the last issue of control over the file would be. In the case of complete control point, this number is saved and is also associated with the toa Controlfile own database leader at the next startup. If this is not the case, there is an inconsistency in the stop_checkpoint of the data file and the stop_checkpoint reocrded in the control file, leading to a recovery of the instance.

  There are several types of control points. Similarly, there are several types of SNA as well. Without going into the details of these, IMO, the article simply means that when the control point write over a file passes, oracle updates the file checkpoint on it and this is recorded in the Controlifle. as well.

  HTH
  Aman...

• SNA application

  Hello
  
  Please help me in my doubts about the number of SNA compensation.
  
  (1) YVERT number increased when a transaction is committed.
  When I ran under query to find number of SNA is givig me each time changed number SCN .can you please let know why his change
  
  SQL > select current_scn from v$ database;
  
  CURRENT_SCN
  -----------
  1811512
  
  SQL > /.
  
  CURRENT_SCN
  -----------
  1811513
  
  SQL > /.
  
  CURRENT_SCN
  -----------
  1811514
  
  SQL > /.
  
  CURRENT_SCN
  -----------
  1811515
  
  
  (2) each check is that point SNA is updated in all the .eg headers when the newspaper switch occur, is in this issue of SNA generated time.
  
  Thanks in advance

  Oracle's internal and committing transactions. That is why we see THAT SNA is increased.

• last SNA and last when

  Hello
  on 10g R2 is there any query see last SNA and the latest issue of when?
  Thank you.

  Yes we can get from V$ database or

  dbms_flashback.get_system_change_number package
  ....

• Appeal iPhone issues 7 more

  I recently bought the new iPhone 7 more.  Not only am I having problems with the LTE service, bounce back between 3 G and no service I am now having problems with call connectivity.  When you try to make an outgoing call, I get an automatic response from my carrier (Verizon) "it's Verizon, we are unable to complete your call at this time, please turn off your phone and back and try again."

  It is a known issue with the iPhone 7 and Verizon. Supposed to be Apple and Verizon are seeking him. It has been a problem since the phone was released. Do a Google search or search here on the forums for a temporary solution but not a cure.  But basically to stop the LTE oice and data into data only in the settings.