Delay block drain plug

Similar Questions

• Ask about the delay block drain plug

  Hello

  I have a question regarding delay clean in Oracle block.

  I read below the meta link Note: 40689.1

  Consider a transaction that updates a million row table. This obviously visits a large number of database blocks to make the change to the data. When the user commits the transaction Oracle does NOT go back and revisit these blocks to make the change permanent. It is left for the next transaction that visits any block affected by the update to 'tidy up' the block (hence the term 'delayed block clean out').

  But the location of the table transaction rollback segment can be recycled once it is marked as a clerk.

  If any new transaction tries to visit a block affected by the last update, and numbers on this block is changed and goes to the corresponding rollback segment transaction location of the table, but this location for the transaction rollback segment is recycled as a result of the validation.

  So, how Oracle will take care of this situation?

  Thanks in advance.

  It will do still a drain plug delay block with a "best estimate YVERT" as it can extract is no longer the SCN of the transaction to cancel it.

  See http://www.jlcomp.demon.co.uk/cleanout.html

  Hemant K Collette

• question about sync of drain plug and Eve delay block

  If a session in my primary database applies a large transaction, then it could cause to delay block drain plug, which is writing the changed blocks to the data files in the primary database will be delayed until an attempt is made to read them, now that they will be written to the data files. However redo generation for the big transacation is not delayed, nor is archiving, and so do it again is sent to the database Eve with a minimum of delay. It is not possible or even likely that the large transaction will have been written to pending data files then written to the primary data files? If so, is it important?
  
  Thank you.
  

• why he keep telling me that youtube is blocked a plug-in?

  I'm trying to put a youtube video on a page on my site, but it won't?

  It keeps saying taken blocked

  I bought a plug in Adobe add ons but can't find it and still can't download a video?

  Hello

  Please see the following forum post:

  plugin blocked to ship video youtube html?

  It will be useful,

  Sonam

• (imac) problems related to the FlashDrive also blocked the plug-in!

  Any help out there: blocked plugin, latest version of flash player installed and old uninstalled but imac is still answering playback of any media, witts end now! (apple can't help any further!)

  regards chris.

  Hello

  Please try to activate plug-ins.

  Safari > Preferences > Security

  Internet Plug-ins > "allow all other plug-ins.

  If that is not the problem, follow these steps.

  1. system preferences > other / Flash Player > advanced > clear all

  Press the button 'clear all '.

  2. install Adobe Flash Player.

  http://get.Adobe.com/flashplayer/

  3 Quit Safari.    Restart the computer. Restart Safari.

• Firefox blocks no plug-ins

  Under all: permissions I put plug-ins for 'always ask' under 'all pages '. However if I set any page to "allow" all pages is set to allow. The simply looking at "all pages" will be solved I return to "always ask" for all pages. However, regardless of what is on, plug-ins are played automatically for all pages.

  This always happens in safe mode.

  I'm under openSUSE 12.3.

  I see, Yes, for the moment, there click on the page to unlock them all on the page.

  The following thread explains this change: 24 Firefox click to play the flash plug-in!

  To get the FlashBlock similar behavior with the current Firefox, the thread suggests this extension: https://addons.mozilla.org/en-US/firefox/addon/click-to-play-per-element/

• Satellite M60-128: start: black screen/delay/blocking

  Hello guys,.

  I have a strange problem with a Satellite M60-128.
  When I start the laptop there are a few problems:

  * Sometimes the remains of black screen (no Toshiba logo) and the laptop does not start
  * Sometimes the laptop starts normally (when he hung before and I turned off with the power button)
  * Sometimes the Toshiba logo is visible but stop there

  I also sometimes have a problem that the USB ports does not work. When I reboot, it works fine. When the USB ports fail, there is a warning in devices.

  I made an update of the BIOS (v1.60) but the problem remains.

  I noticed this: when the laptop does not start and I 'click' on the right button of the Toshiba logo toutchpad is visible and Notepad starts.

  Anyone familiar with this problem or some knows a solution? Thanks for advantage.

  Andy

  > I noticed this: what laptop doesn t start and I 'click' on the keypad touch s right button the Toshiba logo is visible and Notepad starts

  Very strange question usually the laptop should automatically start without pressing the button of the touchpad. For me, this is meaningless and it looks a bit like a motherboard problem
  What do you think about this?

  Have you tried to reinstall the operating system with the recovery CD Toshiba delivered?
  Maybe you should do to make sure this isn't a software problem

  Best regards

• difficult interview question

  Hello world

  I have a question that was asked in an interview, and I didn't know how to respond.  Here's the question:

  < pre >

  assuming today ' today the users run query in oracle and everything is running fast.  the user's home and the next day they ran same or similar request and the queires take time to run.

  What can be the problem?

  < / pre >

  I tried to respond to data volume can be change, his stats are out-of-date, variation on one of the parameters in the init file and so on.  the interviewer told me that nothing has changed at all.

  the database is the same since yesterday and nobody don't touch.  He then followed

  < pre >

  Assume that all members of society went to vacation and before they log off all their requests turned quickly. When they log off, noone touch the database.  When they came back and relaunched queries.

  they were running slow.  What could be the problem?

  < / pre >

  I could not answer.  everyone wants to give ideas on that?

  the interviewer told me that nothing has changed at all.

  the database is the same since yesterday and nobody don't touch.  He then followed

  Sorry - but in today's world, it's just NOT possible that "nothing has changed at all".

  Something has changed, or queries may run the same as before.

  You must determine what has changed and HOW it has changed. The possibilities that you have listed are appropriate.

  Oracle is ALWAYS doing something, and most systems have jobs that automatically generate stats from one day to the next. As others have suggested even a SELECT query will change things:

  1 delay block drain plug may occur generating changes and UNDO/REDO

  2. the buffer cache can rinse at least partially when the new blocks are brought

  3 If ANY user running DML (insertions, changes, deletions) then all sorts of things are going to change both in memory and on the same whether disc DML is NEVER committed.

  The FIRST thing I wonder so ANY statement made by a PERSON who "nothing at all".

  Unless the interviewer is coming with more information on what the system was doing really, how it was configured, what types of statements users were execution, etc. that I held by original suggestions.

• TRUNCATE = CLEAR

  Hi all
  
  11g and 10g
  
  I'm truncating a large table and it took 1 hour to complete :(
  
  If I put my database to force logging, is to say that truncate table is required to connect and behave like remove the command?
  
  
  Thank you very much
  
  zxy

  Logging is again. See http://www.orafaq.com/wiki/Nologging_and_force_logging

  Your problem can be written of the trend of Oracle to make lazy databases. He hastens to write things in memory then the dbwr write whenever please very well, which could never be in the case of the delay block drain plug. Why is it not a problem? Again being the critical writing for Oracle to know with certainty that something is true when you need to recover. That's why you should make a backup just after operations nologging, because things aren't in the stream again and use the force logging to databases pending, which are essentially continuous recovery.

  It is possible for some effects of performance to see if you have the discord between redo and data files. But it is indirect, is not causative likely what you're talking about. And then, if you have some sort of remake drafting problem, who knows? Probably, you should check that Oracle wait indeed.

• 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

• Estimating redo size of alter table DROP COLUMNS CONTINUE checkpoint of 10000

  Hello
  in my 10.2.0.3, I've got table size 90 GB suffering:
  ORA-12986: columns in partially suspended state. Propose to ALTER TABLE DROP COLUMNS CONTINUE
  I need to know how to estimate the size of redo of the:
  change the control of MORE of COLUMNS DROP table 10000 point.
  Is 2 x good estimate of table size?
  Kind regards.
  Greg

  GregG says:
  Please clarify for me how are distinguished between nitrifiants delay block trial and lower real column continue the process.
  Looks like DBC process will increment statistics such as:

  drain plug - number of calls ktugct
  gullies only - consistent read gets

  It's a good indicator, even if I think the specific statistics could be:

      commit txn count during cleanout
  

  I think it's one that tells you that you have made a change of "validation of transaction" to a block.

  I don't know why the CBD process is such redo intensive, is not on the update of ITL bit in db blocks only?

  It updates the inputs ITL and lock bytes, and it takes only entry of redo block; the overload of the roll forward database is in the tens of bytes is small compared to the 240 bytes per row of the column to fall - but if you have a large number of blocks to go before continue it really starts to have an effect, you might be fooled.

  WARNING - I haven't checked to see if delay block drain plug behaves (or even happens) on Delete column in the way that it would perform a simple update in bulk.

  Concerning
  Jonathan Lewis

• ORA-01555 while creating indexes

  Hello, is
  I create an Index on a partitioned table that is very large. The table is about 250 GB in size. The table is not yet used by one, neither read nor written.
  
  The create statement:
  
  CREATE A UNIQUE DASSERVER INDEX. PI_ALL ON DASSERVER. ALL THE
  (SENDERIP, SENDEZEIT, LFDNUMMER)
  NOLOGGING
  PCTFREE 10
  INITRANS 2
  MAXTRANS 255
  STORAGE)
  INITIAL 8192 M
  NEXT 1024M
  MINEXTENTS 1
  MAXEXTENTS UNLIMITED
  DEFAULT USER_TABLES
  )
  LOCAL
  (
  DASSERVER_2006 PARTITION
  TABLESPACE DASSERVER_2006
  STORAGE (INITIAL 1536M),
  DASSERVER_2007 PARTITION
  TABLESPACE DASSERVER_2007,
  DASSERVER_2008 PARTITION
  TABLESPACE DASSERVER_2008,
  DASSERVER_2009 PARTITION
  TABLESPACE DASSERVER_2009,
  DASSERVER_2010 PARTITION
  TABLESPACE DASSERVER_2010
  )
  NOPARALLEL;
  
  The error:
  
  CREATE A UNIQUE DASSERVER INDEX. PI_ALL ON DASSERVER. ALL THE
  *
  FEHLER in line 1:
  ORA-01555: Snapshot zu alt: medium 18 Rollback-Segmentnummer ' _SYSSMU18$ ' STI
  zu klein.
  
  Anyone a suggestion that I should try? I don't have the space on my drives to 250 GB rollback segments. I need space? Why? I don't understand! I thought the 1555 error occurs only when the concurrent transactions occur.
  
  Thanks in advance!
  
  Nanga

  I essentially agree with Sean. Select the rows of the table, and then try again to create the index. If there is a problem of delayed block drain plug the data selection should eliminate it.

  While you index works check v$ transaction and make sure that no developer/dba accesses the target table. If someone you can spend and "kick" them a couple of times. 8-)

  HTH - Mark D Powell.

• DataBlock wrote

  When a checkpoint accurs.
  
  1 order of log file.
  2. within the meaning of the parameter log interval control point.
  3. change the system checkpoint.
  Process CKPT DBWR to write blocks signals only Sales in to datafile. Seizure LGWR writes all the sql statements in the redo log from the log buffer.
  
  While the rest of the events associated with each poress trigger them to do their job.
  
  When LGWR writes the online redo logs?
  . At the checkpoint
  • To engage
  • When a third complete
  • When there is 1 MB ofredo
  • Every three seconds
  • Before DBWn wrote
  
  When do the DBWR write in the data files?
  • Control point occurs
  • Dirty buffers reach the threshold
  • There is no free buffers
  • Time-out occurs
  • RAC ping is requested
  • Tablespace OFFLINE
  • Read-ONLY Tablespace
  • To REMOVE or TRUNCATE table
  • Tablespace BEGIN BACKUP
  
  What are the responsibilities of CKPT?
  • Signalling DBWn at control points
  
  SMON process-
  • Update the headers datafile with control point information
  • Update of the control files with the control point information
  
  So my question is if cache buffers data obtained so DBWR full needs to write data files blocks.
  but no commit problem user... ghoulish data files have uncommitted data and lgwr process as sql statements written in redo then redo files files also have uncommitted statements...?
  whenever written dbwr block lgwr writes too...?
  
  Can someone write the entire process of writing the blocks of data in files...?

  OK, let's see if this example helps clarify the situation.

  Suppose you make an update of a very large table, and she fills the buffer with lots of stamps Sales cache.

  Now, suppose that sessions begin with "free buffer waits. In other words, these sessions meeting that error will score DBWR to wake up and get to work some of the blocks Sales write to disk, which makes them eligible to be aged out of the buffer. However, DBWR cannot and will not write data in data files until it is written in the restore log file by progression online. Thus, DBWR will report LGWR to ensure that changes to the blocks is subject to write are already written again. Then, DBWR is free to write buffers of data files. Note that data LGWR empty the log buffer and written for recovery logs might contain uncommitted data. Thus, the redo and undo and data files can contain uncommitted data, all the way to the disc.

  So, what is happening? How Oracle can treat all of these uncommitted data written everywhere? What happens if there is an accident? Well, okay, first, let's assume that, in the case of any accident, there are several thousands buffers that have been updated with a session, and they're all written offshore on the disc and 10 minutes later, that the session is finally committed. What is going on? Well, validation will be written to the log of restoration by progress. Thus, a "marker of validation" going again and is written to the disk. This will mark the transaction posted in the rollback segment header. Beyond that, nothing to another has to happen immediately. Oracle is very good to delay work at the latest. Thus, the blocks in datafile show still as non-validated and point to the (now engaged) transaction that is listed in the undo segment header. The next time the block is read from the disk, Oracle will 'delay block drain plug' and clean up these pointers flying over. It will read the block header, see pointers to the transaction, go read the header block to cancel, to find the transaction is validated and update the datablock accordingly.

  So, ok, this is all fine and good, and good, but what happens if the instance crashes with non-validated data in the data files? Well, ok, in the case of an instance crash, what happens? Oracle will read headings of the control file and all data files, it uses this information to determine the last valid checkpoint for each data file and now he knows how far back in online redo log stream, he must go and it will start right here and roll forward, reading all these transactions (this includes all the transactions that have committed and who have been posted in the proceeding's) crushed). So now, once it is renewed at the current point in time, all data should find data files, including data from these uncommitted transactions. But wait, that data uncommitted is not valid, the cause of the transactions that were in progress, are now gone, cause that they were lost when the instance has crashed! So, Oracle will read the cancellation of segment headers and find all uncommitted transactions are still before the accident and set back.

  So we roll forward to recover all transactions to redo, and then we restore using data for annulment to clean uncommitted transactions (lost). In this way, Oracle guarantees the integrity of the data up to the last transaction committed, in the case of a defect of the instance.

  Hope that helps,

  -Mark

• Info of the CNS in the block header

  Hi guys,.
  
  Maybe someone can post a link or something (I couldn't find one) where there is a good description of the SNA in the data block header, things
  
  For example, [http://www.adp-gmbh.ch/ora/concepts/db_block.html | http://www.adp-gmbh.ch/ora/concepts/db_block.html] YVERT and the SNA sequence numbermentioned, but what is the difference between the two? And [http://www.informit.com/articles/article.aspx?p=20684 | http://www.informit.com/articles/article.aspx?p=20684] has a diagram that represents the header of a data block containing the Basic YVERT YVERT Wrap, Seq, SNA of latest cleanup, clerk YVERT of free credits space.
  
  I hope you see my point, it's quite confusing. Maybe one of you knows a good link which explains this kind of things well?
  
  Thank you.

  Oracleguy,
  Well that wouldn't be included in any document that has more than one free internet connection. Only Oracle support can get the clear picture on this subject. I'll try to tell you some info that I know. Hope that helps.
  CPN is of two types. One is called system commit number and one is called system change number. The number of system change is used for blocks and represnts the news when an obtained block modified and are also the oldest and the most recent changes that occur to the block. They are used to control changes in the flow of food by progression.
  System commit number is associated with the entire database. This is used to represent the State of consistency of the data with operations that are committed.
  Basis of SNA and Wrap are the numbers that keep incrementing of the SNA. The basis of the CNS is incremented for each SNA increment. When the base reaches a limit, it is incremented YVERT Wrap.
  This link shows the info about them in a clearer way.
  http://Sai-Oracle.blogspot.com/2006_03_01_archive.html

  Cleantout YVERT is the SNA that was there when the YVERT block drain plug happened.*Committed * is the RCS when the block got a validation.
  I don't know the last Credit of free space.
  Well, I found something for her,
  http://books.google.com/books?id=TuzniwcsNtUC&pg=PA392&lpg=PA392&dq=what+is+Committed+SCN+Free+Space+Credits+%2B+oracle&source=web&ots=oEyANU6rpb&sig=kqAlpB2YO6eJmrJp7Z7DzcsBdCA&hl=en&sa=X&oi=book_result&resnum=1&ct=result#PPA392,M1
  This represents the number of bytes stored for validation. I don't know what is the usefulness of this, but still, there is something that is better than nothing.
  What I told you is based on what little I know, but I don't think that there is any document on free sites that explains it clearly. On metalink too, this is not clearly explained. But I hope that you have at least an idea.
  This link of IXORA should also help.
  http://www.Ixora.com.au/notes/cache_header.htm
  HTH
  Aman...

  Published by: Aman... on November 30, 2008 18:15
  link added

  Published by: Aman... on November 30, 2008 18:24
  link added to FSC

• It takes Explantion on Statisticsgenrated grace set autotrace on statistics:

  Select * places;
  

  Statistics
  ----------------------------------------------------------
          562  recursive calls
            0  db block gets
          122  consistent gets
            7  physical reads
            0  redo size
         2129  bytes sent via SQL*Net to client
          392  bytes received via SQL*Net from client
            3  SQL*Net roundtrips to/from client
            6  sorts (memory)
            0  sorts (disk)
           23  rows processed

  I was trying to understand the statistics, I run several queries to view statistics, at one point I got stuck.
  
  I saw that db block gets and Redo size were always zero.
  
  So would you please tell me for example... When I'll be getting a zero db block gets and Redo sizevalues.
  
  Concerning
  
  UMI

  Assuming that the answers you received may have not answered your question:

  The documentation for 'db block gets. "
  (http://download.oracle.com/docs/cd/E11882_01/server.112/e17110/stats002.htm) is perhaps not very clear: 'number of times that a block of COURSES was requested.

  What is a CURRENT block? It is a block that is retrieved in order to retrieve the current data version - as in "what is the version of the data * now *", not "what was the version of the data at a certain point in time. The latter is 'get consistent '.

  Queries are 'consistent gets' because they need to get a consistent reading of all the blocks that they consider.
  A query that starts at 01:01:01, but works for 5 minutes and 10seconds to 01:06:11 must be able to read all the blocks, as it existed at 01:01:01. If it finds, during the reading of all the blocks, he needs to satisfy the request, that one or more blocks have been modified by other transactions of sessions/users, these blocks are 'cancelled' (in memory!) to a previous image - image from 01:01:01. This ensures that each block read by the application conforms to the same point in time.
  (I have simplified this by referring to a point in time, Oracle actually uses SNA, not clock-time to determine "the same point" in time).
  The other an SQL operation that needs to update a block - for example a DML as an UPDATE or a DELETE - needs the current version of each block, it reads. He doesn't 'dismantling' the blocks for a while. It's a GET CURRENT (which is indicated by the statistics called "db block gets") for each block.

  Size of roll FORWARD is, of course, the volume of recovery (in bytes) that has generated the SQL operation. DML generates Redo used by Oracle to ensure that the database can be recovered to a consistent state. Queries, generally, don't generate redo.
  (I say "usually" because a situation called "delayed the block drain plug" causes also to generate queries again for the 'cleansing' operation - but it is something a bit Advanced to study).

  Hemant K Collette
  http://hemantoracledba.blogspot.com