질문-Redo LOG 와 RollBack Segment 와의 상관관계에 대해서

Redo LOG 와 RollBack Segment 와의 상관관계 및 기능에 대해서 정확하게 알고 싶은데여?

저도 이부분에 대해서 한참 고민을 해봤고..
작년인가에.. 미국 오라클 본사에 있는 아는 분하고..
한국 오라클에서 십여년간 일하신 분에게도 여쭈어 보았는데..;;;
오라클은 SCN기반이고, redo log 와 rollback segment가 모두
scn기반으로 움직인다는 것의 상관관계를 빼고는 전혀 두개는
서로 연관성이 없다고 합니다.
redo log는 DB가 비정상종료되었을 경우에, commit을 했으나
데이터파일에 적용하지 못한 데이터에 대해서 rollforward를 수행하고,
또한 DB에 대한 변경사항대해서 저장만 하는 기능을 할 뿐 redo를
가지고 rollback을 하지는 않습니다. 즉 redo는 말 그대로 REDO
다시쓰기(재실행) 이지요. commit했으나 데이터파일에 쓰지 않은 데이터를
다시쓰기(재실행)하는 기능입니다.
그렇다면.. rollback segment는 commit하지 않은 데이터에 대해서
rollback을 하는 기능을 가집니다. rollforward와는 전혀 관계가
없겠죠..
이 두가지 작용을 통해서 DB에서 트랜잭션의 rollforward, rollback을
수행하나 그것은 SCN을 기반으로 작동 될 뿐 서로 어떤 연관성은
가지고 있지 않다고 합니다.
글 수정:
민천사 (민연홍)
그렇다면 대량 트랜잭션이 일어나고 redo log에 write하는 데이터와
undo에 쓰는 데이터는 관련성이 없을까요? 이 때 redo log는 트랜잭션에
대한 복구를 위한 로그를 남기는 역할 일 뿐이지 undo와 관련성을
가지지 않습니다. 관련성을 따지자면 "redo는 undo로 복제되는 실 데이터(변경전 데이터)에
대해서 복구로그를 쌓는다"는 것이됩니다. 차후에 트랜잭션 rollback
은 redo를 참조하는 것이 아니라 undo만을 참조하고, rollback하는
과정의 로그를 redo에 기록하는 것일 뿐입니다.

Similar Messages

  • Fundamental questions on redo logs and rollbacks

    Hi all,
    Some basic questions, I really want to understand it very clearly.
    Suppose that we have updated few records in a table. We know that the blocks to be updated will be fetched into buffer cache, they will be updated with new value and commited eventually. The questions I have are ,
    1) What exact information will go to redo log ? is it a copy of the block before change and copy of the block after change ?
    2) What exactly goes to rollback segment? is it copy of block before change (for update) and just the rowid for inserted row and the copy of block for a deleted row ?
    3) Whatever we do, is it the whole block that goes to redo or rollback ? Means if there are 10 rows in the block and we update one of them, still whole block goes to redo or rollback ?
    4) If we rollback, what goes where ? Is there anything that goes to redo if we rollback ?
    Please explain.
    Thanks.

    Redo stores changes made in the database, and undo/rollback stores the reverse of those changes. Data blocks may be changed prior to a commit, and recorded in both locations.
    So, when a database is recovered, redo is applied to the backup datafiles, rolling every change forward, and then undo is applied to reverse any uncomitted transactions.
    Undo/rollback can also be used simply to roll back a transaction in an active instance. Redo is only used during instance recovery.
    I don't know if this is tracked via the storage of block images, or if it just stores the change itself.
    -cf

  • How to online datafile of rollback segment of NO archive log available

    I set offline datafile of rool back segement and rename it
    but when I try to online , get error to recover
    I try to recover but unfortunately all archive log was deleted ( kind of cron job in unix aotu delete these file)
    Pls advice how can I set this data file online without the archive log ( while databse still up and running) Oracle version is 8i not possible to drop datafile by sql.
    in roll back segment I have 3 data files as below and the rb04.dbf is offline
    usr/Systems/1354RM_1_7.1_Master/databases/dbsnml/data/rbs01.dbf
    /usr/Systems/1354RM_1_7.1_Master/databases/dbsnml/data/rbs03.dbf
    /usr/Systems/1354RM_1_7.1_Master/databases/dbsnml/data/rbs04.dbf
    sequence of what I did is below:
    SQL> alter database datafile '/usr/Systems/1354RM_1/databases/dbsnml/data/rbs04.dbf' offline;
    Database altered.
    SQL> alter tablespace RBS rename datafile '/usr/Systems/1354RM_1/databases/dbsnml/data/rbs04.dbf' to '/usr/Systems/1354RM_1_7.1_Master/databases/dbsnml/data/rbs04.dbf';
    Tablespace altered.
    SQL> alter database datafile '/usr/Systems/1354RM_1_7.1_Master/databases/dbsnml/data/rbs04.dbf' online;
    alter database datafile '/usr/Systems/1354RM_1_7.1_Master/databases/dbsnml/data/rbs04.dbf' online
    ERROR at line 1:
    ORA-01113: file 13 needs media recovery
    ORA-01110: data file 13:
    '/usr/Systems/1354RM_1_7.1_Master/databases/dbsnml/data/rbs04.dbf'
    SQL> recover datafile '/usr/Systems/1354RM_1_7.1_Master/databases/dbsnml/data/rbs04.dbf';
    ORA-00279: change 71449081 generated at 12/23/2008 20:18:05 needed for thread 1
    ORA-00289: suggestion :
    /usr/Systems/1354RM_1_7.1_Master/OSRES/data/warm_repl/WarmArchive/arch_1_455922.
    arc
    ORA-00280: change 71449081 for thread 1 is in sequence #455922
    Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
    ORA-00308: cannot open archived log
    '/usr/Systems/1354RM_1_7.1_Master/OSRES/data/warm_repl/WarmArchive/arch_1_455922
    .arc'
    ORA-27037: unable to obtain file status
    HP-UX Error: 2: No such file or directory
    Additional information: 3

    SQL> alter tablespace RBS rename datafile '/usr/Systems/1354RM_1/databases/dbsnml/data/rbs04.dbf' to '/usr/Systems/1354RM_1_7.1_Master/databases/dbsnml/data/rbs04.dbf';Did you rename the file at OS level after you issued above command? Oracle will not rename the file at OS level.
    Other than that, if you plan to change rollback segment tablespace, better create a new one and create new rollback segment in new tablespace and drop the old one.

  • Rollback segments - database logging

    Got a problem...
    We are trying to move data from one database to another using: INSERT INTO table1 (SELECT a,b,c FROM table2@db2). The problem we are having is that the amount of data being moved with this in sert command is too great - we are getting an error indicating that our rollback segment is not large enough - ORA-01562: failed to extend rollback segment number 4.
    Unfortunately, we are not going to be able to increase the size of the rollback segment any further than we already have. Is there a way to disable the database logging that occurs?
    I tried using INSERT INTO table1 dbms_disable_logging (SELECT a,b,c FROM table2@db2), but noticed no difference - same error.
    Any ideas?
    Thank you,
    Dan

    We use select..into all the time in an unlogged mode for speed and rollback space reasons.
    We replicate fifty million row tables with a minimal amount of rollback segment (<50MB).
    In unlogged mode we can replicate 50 million rows in under forty minutes - that's smokin!
    Oracle version 8 or greater introduced this concept. I am running 8.1.6.
    You need to alter the table to disable logging and then perform the select into.
    The table alter only takes seconds.
    ALTER TABLE IDMDBO.DIM_PLANS NOLOGGING
    Then do the select into and then turn logging back on (if so desired).
    You can also disable logging at the table space level.
    Keep in mind there are only a few database operations that can be performed unlogged and select..into is one of them.
    There is currently no way to carte blanche disable transaction logging - hopefully this will be coming soon!
    Cheers.
    - Brendan Sullivan
    null

  • Cleanup log running transactions ..rollback segments

    Is there any metric in OEM which does the following...
    Am trying to read the document and find the metric which does the following ..not having much luck...
    #* Description : Process to monitor and notify DBA about any in-doubt
    #* transaction which is holding ROLLBACK Segment and
    #* troubling system resources for longer time.
    Thank you

    Below are more details on what it does...trying to find if any metric in OEM does this...thank you
    $sql_text  = "select c.USN  ";
       $sql_text .= ",d.name       ";
       $sql_text .= ",c.EXTENTS , ";
       $sql_text .= "a.username , a.osuser , a.sid , a.process, a.status  ";
       $sql_text .= ",b.start_time ";
       $sql_text .= ",b.status trans_stat, b.used_ublk*value as Bytes_Used ";
       $sql_text .= ",b.used_urec  as Records_used          ";
       $sql_text .= ",start_uext   as First_Extent          ";
       $sql_text .= ",a.MACHINE           ";
       $sql_text .= ",a.TERMINAL        ";
       $sql_text .= ",a.PROGRAM     ";
       $sql_text .= "from v\$session     a,                        ";
       $sql_text .= "     v\$transaction b,                        ";
       $sql_text .= "     v\$rollname    d,                        ";
       $sql_text .= "     (select value from v\$parameter          ";
       $sql_text .= "          where name = 'db_block_size' )  e , ";
       $sql_text .= "     v\$rollstat    c ,                       ";
       $sql_text .= "     dba_rollback_segs f                      ";
       $sql_text .= "where b.ses_addr = a.saddr (+)                ";
       $sql_text .= " and c.usn      = b.xidusn (+)                ";
       $sql_text .= " and d.usn      = c.usn                       ";
       $sql_text .= " and f.segment_id = c.usn                     ";
       $sql_text .= " and a.status     = 'INACTIVE'                ";
       $sql_text .= " and b.used_urec <=${rec_used}                ";
       $sql_text .= " and (round((sysdate - to_date(start_time,'mm/dd/yy HH24:mi:ss'))*1440)) >= ${time_interval} ";
       $sql_text .= " and a.username  <>  'DMIRROR'  

  • Groups and Member in Redo Log

    Hi,
    I would like to the defination and the functionality of Groups and Member in a Redo log file and also the distinction between them
    Thks

    Dear J.C.,
    The redo logs are files that the Oracle server uses to commit or rollback the transactions applied by the users.
    Redo Log files (minimum of two files) record all changes made to the database, hence ensuring that no data is lost in the event of a failure. In case of an instance failure, when the database is next started up, the Oracle server is automatically able to roll forward the transactions that were not applied when the database crashed and roll back the uncommitted transactions from the rollback segments. Hence the database recovers automatically to a consistent state that existed prior to the crash.
    A set of Redo Log files is called a Redo Log Group. Multiple copies (mirroring) of the Redo Log Files are used so as to protect the Redo Log Files from corruption / damage. Each Redo Log File in a Redo Log Group (called Redo Log Member) has essentially the same information, so if one is destroyed, another copy of that file is available for the Oracle server to use.
    Finally, the term Redo Log is used interchangeably with Redo Log Group.
    Ciao!

  • Recovery lost  undo tablespace and Redo log

    Recovery undo tablespace
    [email protected]> shutdown
    Database closed.
    Database dismounted.
    ORACLE instance shut down.e
    [email protected]> exit
    Disconnected from Oracle9i Enterprise Edition Release 9.2.0.1.0 - Production
    With the Partitioning, OLAP and Oracle Data Mining options
    JServer Release 9.2.0.1.0 - Production
    [ora920@tkyte-pc-isdn ora920]$ ls
    control01.ctl cwmlite01.dbf indx01.dbf redo02.log redo0B.log temp01.dbf
    users01.dbf
    control02.ctl drsys01.dbf odm01.dbf redo03.log redo0C.log tools01.dbf
    xdb01.dbf
    control03.ctl example01.dbf redo01.log redo0A.log system01.dbf undotbs01.dbf
    [ora920@tkyte-pc-isdn ora920]$ mv undotbs01.dbf undotbs01.dbf.xxx
    [ora920@tkyte-pc-isdn ora920]$ sqlplus /nolog
    SQL*Plus: Release 9.2.0.1.0 - Production on Sat Sep 28 08:33:29 2002
    Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.
    idle> connect / as sysdba
    Connected to an idle instance.
    idle> startup
    ORACLE instance started.
    Total System Global Area 143725064 bytes
    Fixed Size 451080 bytes
    Variable Size 109051904 bytes
    Database Buffers 33554432 bytes
    Redo Buffers 667648 bytes
    Database mounted.
    ORA-01157: cannot identify/lock data file 2 - see DBWR trace file
    ORA-01110: data file 2: '/usr/oracle/ora920/OraHome1/oradata/ora920/undotbs01.dbf'
    idle> show parameter undo
    NAME TYPE VALUE
    undo_management string AUTO
    undo_retention integer 10800
    undo_suppress_errors boolean FALSE
    undo_tablespace string UNDOTBS1
    idle> alter system set undo_management = manual scope=spfile;
    System altered.
    Note: disabling the undo tablespace here, this'll let us go back to "rollback segments"
    and we'll use the system RBS to get back on our feet
    idle> shutdown
    ORA-01109: database not open
    Database dismounted.
    ORACLE instance shut down.
    idle> exit
    Disconnected from Oracle9i Enterprise Edition Release 9.2.0.1.0 - Production
    With the Partitioning, OLAP and Oracle Data Mining options
    JServer Release 9.2.0.1.0 - Production
    [ora920@tkyte-pc-isdn ora920]$ !sql
    sqlplus /nolog
    SQL*Plus: Release 9.2.0.1.0 - Production on Sat Sep 28 08:35:34 2002
    Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.
    idle> connect / as sysdba;
    Connected to an idle instance.
    idle> startup
    ORACLE instance started.
    Total System Global Area 143725064 bytes
    Fixed Size 451080 bytes
    Variable Size 109051904 bytes
    Database Buffers 33554432 bytes
    Redo Buffers 667648 bytes
    Database mounted.
    ORA-01157: cannot identify/lock data file 2 - see DBWR trace file
    ORA-01110: data file 2: '/usr/oracle/ora920/OraHome1/oradata/ora920/undotbs01.dbf'
    Note: we still have to get rid of that thing..
    idle> alter database datafile '/usr/oracle/ora920/OraHome1/oradata/ora920/undotbs01.dbf'
    2 offline drop;
    Database altered.
    idle> alter database open;
    Database altered.
    idle> drop tablespace undotbs1;
    Tablespace dropped.
    idle> create UNDO tablespace undotbs1
    2 datafile '/usr/oracle/ora920/OraHome1/oradata/ora920/undotbs01.dbf' size 25m
    3 autoextend on next 1m maxsize 1024m;
    Tablespace created.
    idle> alter system set undo_management = auto scope=spfile;
    System altered.
    Now, we've put the undo tablespace "back" by creating a new one. Just bounce...
    idle> shutdown
    Database closed.
    Database dismounted.
    ORACLE instance shut down.
    idle> exit
    Disconnected from Oracle9i Enterprise Edition Release 9.2.0.1.0 - Production
    With the Partitioning, OLAP and Oracle Data Mining options
    JServer Release 9.2.0.1.0 - Production
    [ora920@tkyte-pc-isdn ora920]$ !sql
    sqlplus /nolog
    SQL*Plus: Release 9.2.0.1.0 - Production on Sat Sep 28 08:40:51 2002
    Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.
    idle> connect / as sysdba;
    Connected to an idle instance.
    idle> startup
    ORACLE instance started.
    Total System Global Area 143725064 bytes
    Fixed Size 451080 bytes
    Variable Size 109051904 bytes
    Database Buffers 33554432 bytes
    Redo Buffers 667648 bytes
    Database mounted.
    Database opened.
    idle> show parameter undo
    NAME TYPE VALUE
    undo_management string AUTO
    undo_retention integer 10800
    undo_suppress_errors boolean FALSE
    undo_tablespace string UNDOTBS1
    idle>
    and we are right back where we started from
    RECOVERY REDO TABLESPACE
    STARTUP MOUNT;
    RESTORE DATABASE;
    RECOVER DATABASE UNTIL SEQUENCE $v_seq THREAD 1;
    ALTER DATABASE OPEN RESETLOGS;

    [email protected] wrote:
    just ignore first one like title
    Alter database open resetlog is not necessary to open database ?
    Regards
    kmphttp://download.oracle.com/docs/cd/B19306_01/backup.102/b14191/osrecov.htm#i1007426
    About Opening with the RESETLOGS Option
    The RESETLOGS option is always required after incomplete media recovery or recovery using a backup control file.
    You did not do an incomplete media recovery nor a recovery using a backup control file.

  • Datafile containing rollback segment crashed

    Hi,
    In one of our production box (oracle 8.1.7.4 and HP UX), datafile containing rollback segment crashed. To open the database, i commented rollback segment line in init file and started the db and brought the crashed datafile to offline for dropping as
    alter database datafile '/db10/rollback/rbs01.dbf' offline drop;
    and then tried to drop the tablespace containing that datafile but it threw an error saying an active rollback segment R0 is still there in the tablespace. I donot know how to drop this and create new rollback segments. Any help would be greatly appreciated.
    Thanks
    Guna

    Hi,
    Serious case. In case of a failure the instance recovery is automatic but the rollback segments are needed. Having the database open does not mean everything is OK. Just read that :
    Crash or instance recovery consists of the following steps:
    +# Rolling forward to recover data that has not been recorded in the datafiles, yet has been recorded in the online redo log, including the contents of rollback segments. This is called cache recovery.+
    +# Opening the database. Instead of waiting for all transactions to be rolled back before making the database available, Oracle allows the database to be opened as soon as cache recovery is complete. Any data that is not locked by unrecovered transactions is immediately available.+
    +# Marking all transactions system-wide that were active at the time of failure as DEAD and marking the rollback segments containing these transactions as PARTLY AVAILABLE.+
    +# Rolling back dead transactions as part of SMON recovery. This is called transaction recovery.+
    +# Resolving any pending distributed transactions undergoing a two-phase commit at the time of the instance failure.+
    +# As new transactions encounter rows locked by dead transactions, they can automatically roll back the dead transaction to release the locks. If you are using Fast-Start Recovery, just the data block is immediately rolled back, as opposed to the entire transaction.+
    What did you do exactly after the crash ? Can you post commands/output + last 50-100 lines of your alert.log ?
    Best regards
    Phil

  • Online Redo Log groups

    Dear All,
    How to check the health of redo log file, we have 200 MB undo tablespace in our production server is it enough for huge transactions. Can I check how much time my redo log file data have been overwritten?
    Further in which situation we will add Online Redo Log Groups and which situation we will add Log Members.
    My rollback segment is using System tablespace is it recommended?
    What is recommendation about 1 redo log group is redo log member or 1 redo log group is multiple redo log members.

    Thanks Mr. Nicolas. for your informative guidence.
    Can I check how much time my redo log file data have been overwritten?Check v$loghist.
    We have 218 records in v$loghist, it means 218 times data have been overwritten, i think its not good. Can you guide me how to rectyify this.
    in which situation we will add Online Redo Log GroupsIn case of checkpoint not complete reported into alert.log.
    How to findout checkpoint entry in alert.log
    which situation we will add Log Members.This is the redolog multiplexing, at least two members for each redolog group.
    Ok, Can we do multiplexing for members or just do for groups.
    My rollback segment is using System tablespace is it recommended?No.
    OK, can we change rollback segments tablespace.
    1 redo log group is redo log member or 1 redo log group is multiple redo log membersA minimum of two redolog group with two members for each.
    After, it depend of your db activity.
    We have just one member for each group and we have three groups, so whats ur recommnedation we will add 1 member in each group.

  • ......Redo  Log and Recovery

    Hi,
    I am a bit confused on the Oracle Recovery structure. As far as we know, whenever oracle updates a row, it writes the new value in the DB Buffer Cache, Old value in the Undo Segment. Which value is then written in the Logfiles or the Logbuffer? How they can be used as recovery structure. Do they contain Old Value or the New Value.
    Your kind response will help most of us as we normally forget these basic things.
    It would be best if you can highlight the steps and values etc .
    Thanks once again:

    Redo logs contain two kinds of statements.
    SQL_UNDO and SQL_REDO
    SQL_UNDO is the statement which will revert the particular transaction (required if you need to rollback)
    SQL_REDO is the statement which will complete the transaction (required if you roll forward).
    Archive logs can be used via log miner to find out what was the statement fired to get the table to a particular state (lengthy job though).

  • SYSTEM Rollback Segment bad

    I ported a database over to a new server.
    It seems there may be transactions pending...which I don't care about.
    I can log as SYS and run queries, but I cannot run DML or DDL statements.
    I have narrowed down the problem to the SYSTEM rollback segment.
    I am running in Automatic Undo mode.
    How do I clear transactions from a rollback segment?
    I don't think I can alter or create a new SYSTEM rollback segment.

    There is no error message.
    When I issue any DML/DDL statement Oracle just hangs forever...and never issues an error message.
    Here is the latest printout from the alert.log file:
    Tue Jul 11 14:33:03 2006
    LGWR: Primary database is in CLUSTER CONSISTENT mode
    Tue Jul 11 14:33:03 2006
    ARCH: Evaluating archive log 3 thread 1 sequence 14697
    ARCH: Beginning to archive log 3 thread 1 sequence 14697
    Creating archive destination LOG_ARCHIVE_DEST_1: 'D:\ORA92\RDBMS\ARC14697.001'
    ARCH: Completed archiving log 3 thread 1 sequence 14697
    Tue Jul 11 14:33:05 2006
    LGWR: Primary database is in CLUSTER CONSISTENT mode
    Thread 1 advanced to log sequence 14700
    Thread 1 opened at log sequence 14700
    Current log# 3 seq# 14700 mem# 0: D:\ORADATA\9.2\ICDB\LOG\LOG3A.ORA
    Successful open of redo thread 1
    Tue Jul 11 14:33:06 2006
    SMON: enabling cache recovery
    Tue Jul 11 14:33:06 2006
    Successfully onlined Undo Tablespace 1.
    Tue Jul 11 14:33:06 2006
    SMON: enabling tx recovery
    Tue Jul 11 14:33:06 2006
    Database Characterset is WE8MSWIN1252
    replication_dependency_tracking turned off (no async multimaster replication found)
    Completed: alter database open
    Tue Jul 11 14:33:53 2006
    SMON: Parallel transaction recovery tried
    Tue Jul 11 14:34:45 2006
    create rollback segment system
    tablespace system
    storage (
    initial 112K
    minextents 1
    maxextents 1
    Tue Jul 11 14:34:45 2006
    ORA-1535 signalled during: create rollback segment system
    tablespace system
    s...
    Tue Jul 11 14:35:02 2006
    Thread 1 cannot allocate new log, sequence 14701
    All online logs needed archiving
    Current log# 3 seq# 14700 mem# 0: D:\ORADATA\9.2\ICDB\LOG\LOG3A.ORA
    Tue Jul 11 14:35:12 2006
    drop rollback segment system
    Tue Jul 11 14:35:12 2006
    ORA-1544 signalled during: drop rollback segment system...
    Tue Jul 11 14:41:33 2006
    alter rollback segment system offline
    Tue Jul 11 14:41:33 2006
    ORA-30019 signalled during: alter rollback segment system offline...

  • Too much redo log files...

    Hi,
    I have a very light application in Oracle 9.2.0.7 in Linux-32bits that is generating 400 logfiles a day. I can´t find why those logs are being generated!
    The only thing relevant in that application is a big table that serves only for insert command (1000 per hour) for audit reasons. But this table was created with NOLOGGING option.
    Redo Size: 4 groups of 40 Mb each.
    The insert statement uses a sequence to generate a unique key. Is this sequence causing my big logfile generation?
    Thanks,
    Paulo.

    Here is the statspack:
    STATSPACK report for
    DB Name         DB Id    Instance     Inst Num Release     Cluster Host
    DB             378381468 DB                  1 9.2.0.7.0   NO      host
                Snap Id     Snap Time      Sessions Curs/Sess Comment
    Begin Snap:      12 28-Jun-07 11:05:11       26   1,198.7
      End Snap:      13 28-Jun-07 12:05:24       29   1,077.2
       Elapsed:               60.22 (mins)
    Cache Sizes (end)
    ~~~~~~~~~~~~~~~~~
                   Buffer Cache:       512M      Std Block Size:         8K
               Shared Pool Size:       512M          Log Buffer:     5,120K
    Load Profile
    ~~~~~~~~~~~~                            Per Second       Per Transaction
                      Redo size:            281,252.38              2,073.48
                  Logical reads:             73,113.76                539.02
                  Block changes:              3,133.29                 23.10
                 Physical reads:                  3.24                  0.02
                Physical writes:                 21.39                  0.16
                     User calls:                 26.12                  0.19
                         Parses:                145.64                  1.07
                    Hard parses:                  0.81                  0.01
                          Sorts:                138.33                  1.02
                         Logons:                  0.69                  0.01
                       Executes:                443.27                  3.27
                   Transactions:                135.64
      % Blocks changed per Read:    4.29    Recursive Call %:    98.97
    Rollback per transaction %:    0.13       Rows per Sort:    17.26
    Instance Efficiency Percentages (Target 100%)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                Buffer Nowait %:   99.99       Redo NoWait %:  100.00
                Buffer  Hit   %:  100.00    In-memory Sort %:   99.99
                Library Hit   %:   99.66        Soft Parse %:   99.44
             Execute to Parse %:   67.14         Latch Hit %:   99.93
    Parse CPU to Parse Elapsd %:   55.03     % Non-Parse CPU:   99.22
    Shared Pool Statistics        Begin   End
                 Memory Usage %:   91.06   91.23
        % SQL with executions>1:   44.54   39.78
      % Memory for SQL w/exec>1:   43.09   33.89
    Top 5 Timed Events
    ~~~~~~~~~~~~~~~~~~                                                     % Total
    Event                                               Waits    Time (s) Ela Time
    CPU time                                                        3,577    84.73
    log file parallel write                           854,726         359     8.51
    row cache lock                                     56,780         104     2.47
    process startup                                       172          91     2.16
    SQL*Net message from dblink                         5,001          22      .53
    Wait Events for DB: DB  Instance: DB  Snaps: 12 -13
    -> s  - second
    -> cs - centisecond -     100th of a second
    -> ms - millisecond -    1000th of a second
    -> us - microsecond - 1000000th of a second
    -> ordered by wait time desc, waits desc (idle events last)
                                                                       Avg
                                                         Total Wait   wait    Waits
    Event                               Waits   Timeouts   Time (s)   (ms)     /txn
    log file parallel write           854,726          0        359      0      1.7
    row cache lock                     56,780          0        104      2      0.1
    process startup                       172          4         91    530      0.0
    SQL*Net message from dblink         5,001          0         22      4      0.0
    log file sync                       3,015          3         19      6      0.0
    enqueue                               471          1          9     20      0.0
    buffer busy waits                  20,290          0          8      0      0.0
    db file sequential read             3,853          0          6      2      0.0
    SQL*Net more data from dblin       88,584          0          5      0      0.2
    control file parallel write         1,704          0          5      3      0.0
    latch free                          1,404        748          4      3      0.0
    single-task message                   134          0          4     27      0.0
    LGWR wait for redo copy             8,230          1          2      0      0.0
    log file switch completion             60          0          2     32      0.0
    log file sequential read            1,333          0          2      1      0.0
    control file sequential read        4,530          0          1      0      0.0
    db file scattered read                246          0          0      1      0.0
    SQL*Net more data to client         7,292          0          0      0      0.0
    SQL*Net break/reset to clien           72          0          0      1      0.0
    db file parallel write              4,568          0          0      0      0.0
    log file single write                  62          0          0      0      0.0
    async disk IO                       3,410          0          0      0      0.0
    SQL*Net message to dblink           5,001          0          0      0      0.0
    direct path read (lob)                 84          0          0      0      0.0
    direct path read                      318          0          0      0      0.0
    direct path write                     312          0          0      0      0.0
    buffer deadlock                       115        115          0      0      0.0
    SQL*Net message from client        86,475          0     27,758    321      0.2
    jobq slave wait                     4,594      4,532     13,455   2929      0.0
    SQL*Net more data from clien          602          0          1      2      0.0
    SQL*Net message to client          86,481          0          0      0      0.2
    Background Wait Events for DB: DB  Instance: DB  Snaps: 12 -13
    -> ordered by wait time desc, waits desc (idle events last)
                                                                       Avg
                                                         Total Wait   wait    Waits
    Event                               Waits   Timeouts   Time (s)   (ms)     /txn
    log file parallel write           854,744          0        359      0      1.7
    control file parallel write         1,704          0          5      3      0.0
    LGWR wait for redo copy             8,230          1          2      0      0.0
    log file sequential read            1,333          0          2      1      0.0
    control file sequential read        1,849          0          1      1      0.0
    db file parallel write              4,567          0          0      0      0.0
    latch free                             74          0          0      0      0.0
    rdbms ipc reply                        65          0          0      0      0.0
    log file single write                  62          0          0      0      0.0
    async disk IO                       3,410          0          0      0      0.0
    db file sequential read                 1          0          0      8      0.0
    buffer busy waits                       5          0          0      0      0.0
    direct path read                      248          0          0      0      0.0
    direct path write                     248          0          0      0      0.0
    rdbms ipc message                 868,357      6,776     30,095     35      1.8
    pmon timer                          1,204      1,204      3,529   2931      0.0
    smon timer                            154          0      3,514  22816      0.0
    Instance Activity Stats for DB: DB  Instance: DB  Snaps: 12 -13
    Statistic                                      Total     per Second    per Trans
    active txn count during cleanout               2,844            0.8          0.0
    background checkpoints completed                  31            0.0          0.0
    background checkpoints started                    31            0.0          0.0
    background timeouts                            7,956            2.2          0.0
    branch node splits                                15            0.0          0.0
    buffer is not pinned count               324,721,116       89,875.8        662.6
    buffer is pinned count                   308,901,876       85,497.3        630.3
    bytes received via SQL*Net from c          8,048,130        2,227.6         16.4
    bytes received via SQL*Net from d        181,575,342       50,256.1        370.5
    bytes sent via SQL*Net to client          33,964,494        9,400.6         69.3
    bytes sent via SQL*Net to dblink             933,170          258.3          1.9
    calls to get snapshot scn: kcmgss          9,900,434        2,740.2         20.2
    calls to kcmgas                              985,222          272.7          2.0
    calls to kcmgcs                               11,669            3.2          0.0
    change write time                              9,910            2.7          0.0
    cleanout - number of ktugct calls             18,903            5.2          0.0
    cleanouts and rollbacks - consist                 33            0.0          0.0
    cleanouts only - consistent read                 932            0.3          0.0
    cluster key scan block gets                  289,955           80.3          0.6
    cluster key scans                            101,840           28.2          0.2
    commit cleanout failures: block l                  0            0.0          0.0
    commit cleanout failures: buffer                 113            0.0          0.0
    commit cleanout failures: callbac                 96            0.0          0.0
    commit cleanout failures: cannot               3,095            0.9          0.0
    commit cleanouts                           1,966,376          544.3          4.0
    commit cleanouts successfully com          1,963,072          543.3          4.0
    commit txn count during cleanout             309,283           85.6          0.6
    consistent changes                         5,245,452        1,451.8         10.7
    consistent gets                          242,967,989       67,248.3        495.8
    consistent gets - examination            135,768,580       37,577.8        277.0
    CPU used by this session                     357,659           99.0          0.7
    CPU used when call started                   344,951           95.5          0.7
    CR blocks created                                768            0.2          0.0
    current blocks converted for CR                    0            0.0          0.0
    cursor authentications                           886            0.3          0.0
    data blocks consistent reads - un              1,760            0.5          0.0
    db block changes                          11,320,580        3,133.3         23.1
    db block gets                             21,192,200        5,865.5         43.2
    DBWR buffers scanned                               0            0.0          0.0
    DBWR checkpoint buffers written               69,649           19.3          0.1
    DBWR checkpoints                                  31            0.0          0.0
    DBWR free buffers found                            0            0.0          0.0
    DBWR lru scans                                     0            0.0          0.0
    DBWR make free requests                            0            0.0          0.0
    DBWR revisited being-written buff                  0            0.0          0.0
    DBWR summed scan depth                             0            0.0          0.0
    DBWR transaction table writes                  2,070            0.6          0.0
    DBWR undo block writes                        44,323           12.3          0.1
    deferred (CURRENT) block cleanout            745,333          206.3          1.5
    dirty buffers inspected                            1            0.0          0.0
    enqueue conversions                            8,193            2.3          0.0
    enqueue deadlocks                                  1            0.0          0.0
    enqueue releases                           2,002,960          554.4          4.1
    enqueue requests                           2,002,963          554.4          4.1
    enqueue timeouts                                   3            0.0          0.0
    enqueue waits                                    451            0.1          0.0
    Instance Activity Stats for DB: DB  Instance: DB  Snaps: 12 -13
    Statistic                                      Total     per Second    per Trans
    exchange deadlocks                               115            0.0          0.0
    execute count                              1,601,528          443.3          3.3
    free buffer inspected                             30            0.0          0.0
    free buffer requested                      1,196,628          331.2          2.4
    hot buffers moved to head of LRU              26,707            7.4          0.1
    immediate (CR) block cleanout app                965            0.3          0.0
    immediate (CURRENT) block cleanou             10,817            3.0          0.0
    index fast full scans (full)                       0            0.0          0.0
    index fetch by key                       131,028,270       36,265.8        267.4
    index scans kdiixs1                       17,868,907        4,945.7         36.5
    leaf node splits                               4,528            1.3          0.0
    leaf node 90-10 splits                         3,017            0.8          0.0
    logons cumulative                              2,499            0.7          0.0
    messages received                            859,631          237.9          1.8
    messages sent                                859,631          237.9          1.8
    no buffer to keep pinned count                21,253            5.9          0.0
    no work - consistent read gets            87,667,752       24,264.5        178.9
    opened cursors cumulative                    528,984          146.4          1.1
    OS Involuntary context switches                    0            0.0          0.0
    OS Page faults                                     0            0.0          0.0
    OS Page reclaims                                   0            0.0          0.0
    OS System time used                                0            0.0          0.0
    OS User time used                                  0            0.0          0.0
    OS Voluntary context switches                      0            0.0          0.0
    parse count (failures)                             7            0.0          0.0
    parse count (hard)                             2,928            0.8          0.0
    parse count (total)                          526,209          145.6          1.1
    parse time cpu                                 2,778            0.8          0.0
    parse time elapsed                             5,048            1.4          0.0
    physical reads                                11,690            3.2          0.0
    physical reads direct                          6,698            1.9          0.0
    physical reads direct (lob)                      102            0.0          0.0
    physical writes                               77,270           21.4          0.2
    physical writes direct                         7,620            2.1          0.0
    physical writes direct (lob)                       0            0.0          0.0
    physical writes non checkpoint                33,360            9.2          0.1
    pinned buffers inspected                           0            0.0          0.0
    prefetched blocks                                799            0.2          0.0
    prefetched blocks aged out before                  0            0.0          0.0
    process last non-idle time                     3,630            1.0          0.0
    recursive calls                            9,053,277        2,505.8         18.5
    recursive cpu usage                          255,973           70.9          0.5
    redo blocks written                        2,572,625          712.1          5.3
    redo buffer allocation retries                    50            0.0          0.0
    redo entries                               3,074,994          851.1          6.3
    redo log space requests                           60            0.0          0.0
    redo log space wait time                         193            0.1          0.0
    redo ordering marks                                0            0.0          0.0
    redo size                              1,016,164,852      281,252.4      2,073.5
    redo synch time                                1,956            0.5          0.0
    redo synch writes                              5,317            1.5          0.0
    redo wastage                             259,689,040       71,876.3        529.9
    redo write time                               37,488           10.4          0.1
    redo writer latching time                        242            0.1          0.0
    redo writes                                  854,744          236.6          1.7
    rollback changes - undo records a              1,098            0.3          0.0
    Instance Activity Stats for DB: DB  Instance: DB  Snaps: 12 -13
    Statistic                                      Total     per Second    per Trans
    rollbacks only - consistent read                 747            0.2          0.0
    rows fetched via callback                117,908,375       32,634.5        240.6
    session connect time                               0            0.0          0.0
    session cursor cache count                        16            0.0          0.0
    session cursor cache hits                    484,372          134.1          1.0
    session logical reads                    264,160,020       73,113.8        539.0
    session pga memory                        16,473,320        4,559.5         33.6
    session pga memory max                    16,914,080        4,681.5         34.5
    session uga memory                    17,216,514,728    4,765,157.7     35,130.3
    session uga memory max                 1,865,036,296      516,201.6      3,805.6
    shared hash latch upgrades - no w         17,251,803        4,774.9         35.2
    shared hash latch upgrades - wait             24,671            6.8          0.1
    sorts (disk)                                      32            0.0          0.0
    sorts (memory)                               499,747          138.3          1.0
    sorts (rows)                               8,626,333        2,387.6         17.6
    SQL*Net roundtrips to/from client             80,069           22.2          0.2
    SQL*Net roundtrips to/from dblink              5,001            1.4          0.0
    summed dirty queue length                          0            0.0          0.0
    switch current to new buffer                       1            0.0          0.0
    table fetch by rowid                     238,882,317       66,117.4        487.4
    table fetch continued row                  4,436,670        1,228.0          9.1
    table scan blocks gotten                   5,066,302        1,402.2         10.3
    table scan rows gotten                   134,679,712       37,276.4        274.8
    table scans (direct read)                          0            0.0          0.0
    table scans (long tables)                        447            0.1          0.0
    table scans (short tables)                   152,382           42.2          0.3
    transaction rollbacks                            530            0.2          0.0
    transaction tables consistent rea                  0            0.0          0.0
    transaction tables consistent rea                  0            0.0          0.0
    user calls                                    94,382           26.1          0.2
    user commits                                 489,423          135.5          1.0
    user rollbacks                                   653            0.2          0.0
    write clones created in backgroun                 11            0.0          0.0
    write clones created in foregroun                878            0.2          0.0
    Tablespace IO Stats for DB: DB  Instance: DB  Snaps: 12 -13
    ->ordered by IOs (Reads + Writes) desc
    Tablespace
                     Av      Av     Av                    Av        Buffer Av Buf
             Reads Reads/s Rd(ms) Blks/Rd       Writes Writes/s      Waits Wt(ms)
    T1_UNDO
                31       0    0.0     1.0       46,535       13        344    0.4
    T1       
                31       0    0.0     1.0       13,754        4      3,657    0.4
    T2     
             3,308       1    0.8     1.1        2,973        1          0    0.0
    T3       
                31       0    0.0     1.0        5,710        2     16,240    0.4
    T4     
               555       0    4.0     1.0          600        0          0    0.0
    SYSTEM
               429       0    3.9     2.5          280        0         49    0.2
    TEMP
               134       0    0.4    48.1          238        0          0    0.0
    T1_16K          
                31       0    0.0     1.0           31        0          0    0.0
    T2_16K     
                31       0    0.0     1.0           31        0          0    0.0
    Buffer Pool Statistics for DB: DB  Instance: DB  Snaps: 12 -13
    -> Standard block size Pools  D: default,  K: keep,  R: recycle
    -> Default Pools for other block sizes: 2k, 4k, 8k, 16k, 32k
                                                               Free    Write  Buffer
         Number of Cache      Buffer    Physical   Physical  Buffer Complete    Busy
    P      Buffers Hit %        Gets       Reads     Writes   Waits    Waits   Waits
    D       49,625 100.0 263,975,320       4,909     69,666       0        0  20,290
    16k      7,056 100.0          30           0          0       0        0       0
    Instance Recovery Stats for DB: DB  Instance: DB  Snaps: 12 -13
    -> B: Begin snapshot,  E: End snapshot
      Targt Estd                                    Log File   Log Ckpt   Log Ckpt
      MTTR  MTTR   Recovery    Actual     Target      Size     Timeout    Interval
       (s)   (s)   Estd IOs  Redo Blks  Redo Blks  Redo Blks  Redo Blks  Redo Blks
    B     0     0                 10518      10000      73728     186265      10000
    E     0     0                 13189      10000      73728     219498      10000
    Buffer Pool Advisory for DB: DB  Instance: DB  End Snap: 13
    -> Only rows with estimated physical reads >0 are displayed
    -> ordered by Block Size, Buffers For Estimate
            Size for  Size      Buffers for  Est Physical          Estimated
    P   Estimate (M) Factr         Estimate   Read Factor     Physical Reads
    D             32    .1            3,970        205.60      4,726,309,734
    D             64    .2            7,940        111.86      2,571,419,284
    D             96    .2           11,910         59.99      1,379,092,849
    D            128    .3           15,880         32.24        741,224,090
    D            160    .4           19,850         16.05        369,050,333
    D            192    .5           23,820          1.28         29,352,221
    D            224    .6           27,790          1.05         24,077,507
    D            256    .6           31,760          1.03         23,723,389
    D            288    .7           35,730          1.02         23,518,434
    D            320    .8           39,700          1.01         23,328,106
    D            352    .9           43,670          1.01         23,193,257
    D            384   1.0           47,640          1.00         23,064,957
    D            400   1.0           49,625          1.00         22,987,576
    D            416   1.0           51,610          1.00         22,927,325
    D            448   1.1           55,580          0.99         22,824,032
    D            480   1.2           59,550          0.99         22,713,509
    D            512   1.3           63,520          0.99         22,649,147
    D            544   1.4           67,490          0.98         22,605,489
    D            576   1.4           71,460          0.98         22,525,897
    D            608   1.5           75,430          0.97         22,407,418
    D            640   1.6           79,400          0.96         22,022,381
    16k           16    .1            1,008          1.00        139,218,299
    16k           32    .3            2,016          1.00        139,211,699
    16k           48    .4            3,024          1.00        139,207,678
    16k           64    .6            4,032          1.00        139,202,581
    16k           80    .7            5,040          1.00        139,198,339
    16k           96    .9            6,048          1.00        139,193,448
    16k          112   1.0            7,056          1.00        139,188,446
    16k          128   1.1            8,064          1.00        139,183,808
    16k          144   1.3            9,072          1.00        139,179,598
    16k          160   1.4           10,080          1.00        139,175,656
    16k          176   1.6           11,088          1.00        139,170,607
    16k          192   1.7           12,096          1.00        139,166,491
    16k          208   1.9           13,104          1.00        139,162,487
    16k          224   2.0           14,112          1.00        139,158,197
    16k          240   2.1           15,120          1.00        139,153,797
    16k          256   2.3           16,128          1.00        139,149,365
    16k          272   2.4           17,136          1.00        139,144,252
    16k          288   2.6           18,144          1.00        139,140,121
    16k          304   2.7           19,152          1.00        139,135,435
    16k          320   2.9           20,160          1.00        139,130,845
    Buffer wait Statistics for DB: DB  Instance: DB  Snaps: 12 -13
    -> ordered by wait time desc, waits desc
                                     Tot Wait    Avg
    Class                    Waits   Time (s) Time (ms)
    data block              19,912          8         0
    undo header                343          0         0
    segment header              34          0         0
    undo block                   1          0         0
    Enqueue activity for DB: DB  Instance: DB  Snaps: 12 -13
    -> Enqueue stats gathered prior to 9i should not be compared with 9i data
    -> ordered by Wait Time desc, Waits desc
                                                            Avg Wt         Wait
    Eq     Requests    Succ Gets Failed Gets       Waits   Time (ms)     Time (s)
    TM      981,781      981,773           0           7      1,365.43           10
    TX      983,944      983,906           0         412           .59            0
    HW        4,645        4,645           0          32           .09            0
    Rollback Segment Stats for DB: DB  Instance: DB  Snaps: 12 -13
    ->A high value for "Pct Waits" suggests more rollback segments may be required
    ->RBS stats may not be accurate between begin and end snaps when using Auto Undo
      managment, as RBS may be dynamically created and dropped as needed
            Trans Table       Pct   Undo Bytes
    RBS No      Gets        Waits     Written        Wraps  Shrinks  Extends
         0          155.0    0.00               0        0        0        0
         1      202,561.0    0.00      31,178,710       40        2        3
         2      191,044.0    0.00      30,067,156       23        2        6
         3      195,891.0    0.00      30,470,548       39        1        3
         4      203,928.0    0.00      31,822,638       38        2        5
         5      196,386.0    0.00  -4,264,350,168       38        1        3
         6      204,125.0    0.00      32,081,200       24        1        7
         7      192,169.0    0.00      33,732,012       45        3        6
         8      195,819.0    0.00      30,503,550       40        2        2
         9      202,905.0    0.00      31,595,438       40        2        4
        10      195,796.0    0.00      30,566,652       29        4        9
    Rollback Segment Storage for DB: DB  Instance: DB  Snaps: 12 -13
    ->Optimal Size should be larger than Avg Active
    RBS No    Segment Size      Avg Active    Optimal Size    Maximum Size
         0         385,024               0                         385,024
         1      12,705,792         944,176                   2,213,732,352
         2      11,657,216       1,548,937                   2,214,715,392
         3      13,754,368         832,465                     243,392,512
         4      13,754,368         946,902                     235,069,440
         5      12,705,792         964,352                   2,195,374,080
         6      20,045,824       1,232,438                   2,416,041,984
         7      12,705,792         977,490                   3,822,182,400
         8      10,608,640         875,068                     243,392,512
         9      11,657,216         878,119                     243,392,512
        10      18,997,248       1,034,104                   2,281,889,792
    Undo Segment Summary for DB: DB  Instance: DB  Snaps: 12 -13
    -> Undo segment block stats:
    -> uS - unexpired Stolen,   uR - unexpired Released,   uU - unexpired reUsed
    -> eS - expired   Stolen,   eR - expired   Released,   eU - expired   reUsed
    Undo           Undo        Num  Max Qry     Max Tx Snapshot Out of uS/uR/uU/
    TS#         Blocks      Trans  Len (s)   Concurcy  Too Old  Space eS/eR/eU
       1         44,441 ##########       47          2        0      0 0/0/0/0/0/0
    Undo Segment Stats for DB: DB  Instance: DB  Snaps: 12 -13
    -> ordered by Time desc
                         Undo      Num Max Qry   Max Tx  Snap   Out of uS/uR/uU/
    End Time           Blocks    Trans Len (s)    Concy Too Old  Space eS/eR/eU
    28-Jun 11:56        7,111 ########      47        1       0      0 0/0/0/0/0/0
    28-Jun 11:46       10,782 ########      18        2       0      0 0/0/0/0/0/0
    28-Jun 11:36        6,170 ########      42        1       0      0 0/0/0/0/0/0
    28-Jun 11:26        4,966 ########      13        1       0      0 0/0/0/0/0/0
    28-Jun 11:16        6,602 ########      40        1       0      0 0/0/0/0/0/0
    28-Jun 11:06        8,810 ########      10        1       0      0 0/0/0/0/0/0
    Latch Activity for DB: DB  Instance: DB  Snaps: 12 -13
    ->"Get Requests", "Pct Get Miss" and "Avg Slps/Miss" are statistics for
      willing-to-wait latch get requests
    ->"NoWait Requests", "Pct NoWait Miss" are for no-wait latch get requests
    ->"Pct Misses" for both should be very close to 0.0
                                               Pct    Avg   Wait                 Pct
                                  Get          Get   Slps   Time       NoWait NoWait
    Latch                       Requests      Miss  /Miss    (s)     Requests   Miss
    active checkpoint queue           9,585    0.0    0.0      0            0
    alert log latch                     158    0.0             0            0
    archive control                     220    0.0             0            0
    archive process latch               220    0.5    1.0      0            0
    cache buffer handles            264,718    0.0    0.0      0            0
    cache buffers chains        416,051,175    0.0    0.0      4      401,018    0.0
    cache buffers lru chain       1,285,963    0.0    0.0      0    1,206,550    0.0
    channel handle pool latc          4,927    0.0             0            0
    channel operations paren         10,788    0.0             0            0
    checkpoint queue latch          528,319    0.0    0.0      0       69,506    0.0
    child cursor hash table          35,371    0.0             0            0
    Consistent RBA                  854,833    0.0    0.0      0            0
    dml lock allocation           1,963,007    0.9    0.0      0            0
    dummy allocation                  4,995    0.0             0            0
    enqueue hash chains           4,014,593    0.5    0.0      0            0
    enqueues                         94,666    0.0    0.0      0            0
    event group latch                 2,340    0.0             0            0
    FAL request queue                    72    0.0             0            0
    FIB s.o chain latch                 310    0.0             0            0
    FOB s.o list latch                6,769    0.0             0            0
    global tx hash mapping           10,388    0.0             0            0
    hash table column usage              16    0.0             0          479    0.0
    job workq parent latch                0                    0          316    0.0
    job_queue_processes para            116    0.0             0            0
    ktm global data                     200    0.0             0            0
    lgwr LWN SCN                    855,008    0.0    0.0      0            0
    library cache                 5,836,900    0.4    0.0      0        8,926    0.6
    library cache load lock             468    0.0             0            0
    library cache pin             3,510,695    0.0    0.0      0            0
    library cache pin alloca      1,402,523    0.0    0.0      0            0
    list of block allocation          6,115    0.0             0            0
    loader state object free            620    0.0             0            0
    message pool operations             262    0.0             0            0
    messages                      2,664,950    0.4    0.0      0            0
    mostly latch-free SCN           856,000    0.1    0.0      0            0
    multiblock read objects           3,184    0.0             0            0
    ncodef allocation latch              57    0.0             0            0
    object stats modificatio              8    0.0             0            0
    post/wait queue                   6,183    0.0             0        3,082    0.0
    process allocation                4,677    0.0             0        2,340    0.0
    process group creation            4,677    0.0             0            0
    redo allocation               4,784,936    0.5    0.0      0            0
    redo copy                             0                    0    3,081,261    0.3
    redo writing                  2,576,299    0.0    0.2      0            0
    row cache enqueue latch       3,017,144    0.0    0.0      0            0
    row cache objects             5,049,552    0.8    0.0      0           92    0.0
    sequence cache                  984,824    0.0    0.1      0            0
    session allocation              110,417    0.0    0.0      0            0
    session idle bit                205,319    0.0             0            0
    session switching                    57    0.0             0            0
    Latch Activity for DB: DB  Instance: DB  Snaps: 12 -13
    ->"Get Requests", "Pct Get Miss" and "Avg Slps/Miss" are statistics for
      willing-to-wait latch get requests
    ->"NoWait Requests", "Pct NoWait Miss" are for no-wait latch get requests
    ->"Pct Misses" for both should be very close to 0.0
                                               Pct    Avg   Wait                 Pct
                                  Get          Get   Slps   Time       NoWait NoWait
    Latch                       Requests      Miss  /Miss    (s)     Requests   Miss
    session timer                     1,204    0.0             0            0
    shared pool                   2,409,725    0.1    0.1      0            0
    simulator hash latch          7,439,429    0.0    0.0      0            0
    simulator lru latch                 202    0.0             0      128,961    0.2
    sort extent pool                  1,053    0.0             0            0
    SQL memory manager worka             67    0.0             0            0
    temp lob duration state             187    0.0             0            0
    transaction allocation            7,290    0.0             0            0
    transaction branch alloc          5,668    0.0             0            0
    undo global data              3,002,808    0.4    0.0      0            0
    user lock                         8,642    0.0             0            0
    Latch Sleep breakdown for DB: DB  Instance: DB  Snaps: 12 -13
    -> ordered by misses desc
                                          Get                            Spin &
    Latch Name                       Requests      Misses      Sleeps Sleeps 1->4
    cache buffers chains          416,051,175     197,296         750 196776/298/2
                                                                      15/7/0
    row cache objects               5,049,552      42,368          38 42330/38/0/0
                                                                      /0
    redo allocation                 4,784,936      24,766          77 24697/61/8/0
                                                                      /0
    library cache                   5,836,900      23,477         276 23207/264/6/
                                                                      0/0
    enqueue hash chains             4,014,593      21,061          26 21035/26/0/0
                                                                      /0
    dml lock allocation             1,963,007      17,887          16 17872/14/1/0
                                                                      /0
    undo global data                3,002,808      12,350           8 12342/8/0/0/
                                                                      0
    messages                        2,664,950      10,131           5 10126/5/0/0/
                                                                      0
    shared pool                     2,409,725       1,362         189 1175/185/2/0
                                                                      /0
    row cache enqueue latch         3,017,144         470           7 463/7/0/0/0
    mostly latch-free SCN             856,000         434           1 433/1/0/0/0
    library cache pin               3,510,695         345           4 341/4/0/0/0
    sequence cache                    984,824          53           4 49/4/0/0/0
    library cache pin allocati      1,402,523          35           1 34/1/0/0/0
    redo writing                    2,576,299           5           1 4/1/0/0/0
    archive process latch                 220           1           1 0/1/0/0/0
    Latch Miss Sources for DB: DB  Instance: DB  Snaps: 12 -13
    -> only latches with sleeps are shown
    -> ordered by name, sleeps desc
                                                         NoWait              Waiter
    Latch Name               Where                       Misses     Sleeps   Sleeps
    archive process latch    kcrrpa                           0          1        0
    cache buffers chains     kcbgtcr: fast path               0        346      188
    cache buffers chains     kcbgtcr: kslbegin excl           0        163      239
    cache buffers chains     kcbrls: kslbegin                 0         86      170
    cache buffers chains     kcbget: pin buffer               0         53       49
    cache buffers chains     kcbgcur: kslbegin                0         44       20
    cache buffers chains     kcbnlc                           0         38       22
    cache buffers chains     kcbget: exchange                 0          8       16
    cache buffers chains     kcbchg: kslbegin: call CR        0          3       21
    cache buffers chains     kcbget: exchange rls             0          3        2
    cache buffers chains     kcbnew                           0          3        0
    cache buffers chains     kcbbxsv                          0          2        0
    cache buffers chains     kcbchg: kslbegin: bufs not       0          1       23
    dml lock allocation      ktaiam                           0         13        1
    dml lock allocation      ktaidm                           0          3       15
    enqueue hash chains      ksqgtl3                          0         22        2
    enqueue hash chains      ksqrcl                           0          4       24
    library cache            kglic                            0         55        4
    library cache            kglhdgn: child:                  0         42       86
    library cache            kglobpn: child:                  0         26       32
    library cache            kglpndl: child: after proc       0         14        0
    library cache            kglpndl: child: before pro       0         13       73
    library cache            kglpin: child: heap proces       0         12       29
    library cache            kgllkdl: child: cleanup          0         11        4
    library cache            kglupc: child                    0          4        7
    library cache            kgldti: 2child                   0          2        4
    library cache            kglpnp: child                    0          1        4
    library cache pin        kglpnal: child: alloc spac       0          3        3
    library cache pin        kglpndl                          0          1        1
    library cache pin alloca kglpnal                          0          1        0
    messages                 ksaamb: after wakeup             0          3        2
    messages                 ksarcv                           0          2        2
    mostly latch-free SCN    kcslcu3                          0          1        1
    redo allocation          kcrfwr                           0         74        8
    redo allocation          kcrfwi: more space               0    

  • Transaction table in rollback segments

    hi guys,
    I have read the following, but am still having a little difficulty conceptualising. Would someone be kind enough to give me a very brief example?
    thanks
    For each rollback segment, Oracle maintains a transaction table--a list of all transactions that use the associated rollback segment and the rollback entries for each change performed by these transactions.

    First of all, the statement is talking about old manual undo management using rollback segment.
    If you check the preceding two paragraph of the statement then it's easier to understand,
    It basically says, Rollback segment hold rollback entries of transaction. To make it easier to track transactions and undo entries, Oracle maintain a table to save such info.
    Rollback segment , transaction and undo entries are one to many relationships.
    Rollback Segment --< Transactions --< Undo Entries
    http://download.oracle.com/docs/cd/B10501_01/server.920/a96524/b_deprec.htm
    Contents of a Rollback Segment
    Information in a rollback segment consists of several rollback entries. Among other information, a rollback entry includes block information (the file number and block ID corresponding to the data that was changed) and the data as it existed before an operation in a transaction. Oracle links rollback entries for the same transaction, so the entries can be found easily if necessary for transaction rollback.
    Neither database users nor administrators can access or read rollback segments. Only Oracle can write to or read them. (They are owned by the user SYS, no matter which user creates them.)
    How Rollback Entries Are Logged
    Rollback entries change data blocks in the rollback segment, and Oracle records all changes to data blocks, including rollback entries, in the redo log. This second recording of the rollback information is very important for active transactions (not yet committed or rolled back) at the time of a system crash. If a system crash occurs, then Oracle automatically restores the rollback segment information, including the rollback entries for active transactions, as part of instance or media recovery. When recovery is complete, Oracle performs the actual rollbacks of transactions that had been neither committed nor rolled back at the time of the system crash.
    When Rollback Information Is Required
    For each rollback segment, Oracle maintains a transaction table--a list of all transactions that use the associated rollback segment and the rollback entries for each change performed by these transactions. Oracle uses the rollback entries in a rollback segment to perform a transaction rollback and to create read-consistent results for queries.

  • Redo log entries

    what do you mean by change vectors? what exactly do they contain?

    Thank you for your replay.
    checked out the link suggested and found the following content.
    Online Redo Log Contents
    Online redo log files are filled with redo records. A redo record, also called a redo entry, is made up of a group of change vectors, each of which is a description of a change made to a single block in the database. For example, if you change a salary value in an employee table, you generate a redo record containing change vectors that describe changes to the data segment block for the table, the rollback segment data block, and the transaction table of the rollback segments.
    Redo entries record data that you can use to reconstruct all changes made to the database, including the rollback segments.
    but still i am not clear with this concept
    does it contain address of blocks in data & undo segments or the unit by which the data is changing?

  • Can we use online redo log to recover lost datafile in NOARCHIVE mode?

    I am working on OCA exam and confued about these 2 sample questions. (similar questions with totally different answer)
    Please give me hint about the different between these 2 questions.
    ** If the database is in NOARCHIVELOG mode, and one of the datafile for tablespace USERS is lost, what kind of recovery is possible? (answer: B)
    A. All transactions except those in the USERS tablespace are recoverable up to the loss of the datafile.
    B. Recovery is possible only up to the point in time of the last full database backup.
    C. The USERS tablespace is recoverable from the online redo log file as long as none of the redo log files have been reused since the last backup.
    D. Tablespace point in time recovery is available as long as a full backup of the USERS tablespace exists.
    ** The database of your company is running in the NOARCHIVELOG mode. You perform a complete backup of the database every night. On Monday morning, you lose the USER1.dbf file belonging to the USERS tablespace. Your database has four redo log groups, and there have been two log switches since Sunday night's backup.
    Which is true (answer: B)
    A. The database cannot be recovered.
    B. The database can be recovered up to the last commit.
    C. The database can be recovered only up to the last completed backup.
    D. The database can be recovered by performing an incomplete recovery.
    E. The database can be recovered by restoring only the USER!.dbf datafile from the most recent backup.

    I think Gaurav is correct, you can recover to the last commit even in NOARCHIVELOG, as long as all the changes in the redo logs have not been overwritten. So answer should be B for question 2.
    Here is my test:
    SQL> select log_mode from v$database;
    LOG_MODE
    NOARCHIVELOG
    SQL> select tablespace_name, file_name from dba_data_files;
    TABLESPACE_NAME
    FILE_NAME
    USERS
    C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORA101RC\USERS01.DBF
    SYSAUX
    C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORA101RC\SYSAUX01.DBF
    UNDOTBS1
    C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORA101RC\UNDOTBS01.DBF
    SYSTEM
    C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORA101RC\SYSTEM01.DBF
    DATA
    C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORA101RC\DATA01.DBF
    SQL> create table names
    2 ( name varchar(16))
    3 tablespace users;
    Table created.
    so this segment 'names' is created in the datafile users01.
    At this point I shut down and mount the DB, then:
    RMAN> backup database;
    channel ORA_DISK_1: backup set complete, elapsed time: 00:00:29
    Finished backup at 06-OCT-07
    SQL>alter database open
    SQL> insert into names values ('pippo');
    1 row created.
    SQL> commit;
    Commit complete.
    SQL>shutdown immediate;
    Database closed.
    Database dismounted.
    ORACLE instance shut down.
    At this point I delete datafile users01 and restart:
    SQL> startup
    ORACLE instance started.
    Total System Global Area 167772160 bytes
    Fixed Size 1247900 bytes
    Variable Size 67110244 bytes
    Database Buffers 96468992 bytes
    Redo Buffers 2945024 bytes
    Database mounted.
    ORA-01157: cannot identify/lock data file 4 - see DBWR trace file
    ORA-01110: data file 4: 'C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORA101RC\USERS01.DBF'
    restoring the backup taken before inserting the value 'pippo' in table names:
    RMAN> restore database;
    Starting restore at 06-OCT-07
    using channel ORA_DISK_1
    channel ORA_DISK_1: starting datafile backupset restore
    channel ORA_DISK_1: specifying datafile(s) to restore from backup set
    restoring datafile 00001 to C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORA101RC\SYSTEM01.D
    BF
    restoring datafile 00002 to C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORA101RC\UNDOTBS01.
    DBF
    restoring datafile 00003 to C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORA101RC\SYSAUX01.D
    BF
    restoring datafile 00004 to C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORA101RC\USERS01.DB
    F
    restoring datafile 00005 to C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORA101RC\DATA01.DBF
    channel ORA_DISK_1: reading from backup piece C:\ORACLE\PRODUCT\10.2.0\DB_1\DATA
    BASE\0AITR52K_1_1
    channel ORA_DISK_1: restored backup piece 1
    piece handle=C:\ORACLE\PRODUCT\10.2.0\DB_1\DATABASE\0AITR52K_1_1 tag=TAG20071006
    T181337
    channel ORA_DISK_1: restore complete, elapsed time: 00:02:07
    Finished restore at 06-OCT-07
    RMAN> recover database;
    Starting recover at 06-OCT-07
    using channel ORA_DISK_1
    starting media recovery
    media recovery complete, elapsed time: 00:00:05
    Finished recover at 06-OCT-07
    SQL> alter database open;
    Database altered.
    SQL> select * from names;
    NAME
    pippo
    SQL>
    enrico

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