How the transactions will move to mdf from ldf?

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How the transactions will move to mdf from ldf?

Raghavender Chavva

SSCrazy Eights

Points: 8669
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April 14, 2011 at 9:04 am

#237614

Hi All,
Can you please tell me how transactions will commit to mdf from transaction file ? and who will take care of this process?
Thank You.
Regards,
Raghavender Chavva

Viewing 13 posts - 1 through 12 (of 12 total)

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Ron McCullough SSC Guru Points: 63877 More actions · Answer 1

I assume by transaction file you mean the log file

Check points are issued by the system. If you want to know more look up checkpoint and lazywriter. It is an automatic process.

If everything seems to be going well, you have obviously overlooked something.

Ron

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Raghavender Chavva SSCrazy Eights Points: 8669 More actions · Answer 2

Yes, transaction file means transaction log file.

Is WLF will come into the picture here ?

Thank You.

Regards,
Raghavender Chavva

Raghavender Chavva SSCrazy Eights Points: 8669 More actions · Answer 3

Yes, transaction file means transaction log file.

Is WLF will come into the picture here ?

Thank You.

Regards,
Raghavender Chavva

Ron McCullough SSC Guru Points: 63877 More actions · Answer 4

Yes, transaction file means transaction log file.
Is WLF will come into the picture here ?

What do you mean by WLF?

If everything seems to be going well, you have obviously overlooked something.

Ron

Please help us, help you -before posting a question please read[/url]
Before posting a performance problem please read[/url]

Gail Shaw SSC Guru Points: 1004504 More actions · Answer 5

They don't move. Data does not move from the log to the data file.

When a transaction occurs the data page is changed in memory and the log record is written to the log buffer. When the transaction commits, the log buffer is written to disk, to the transaction log (ldf). At some point after that the changed data page is written to the data file.

That's a massive simplification, but it's good enough.

Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

We walk in the dark places no others will enter
We stand on the bridge and no one may pass

kvr1985 SSCommitted Points: 1628 More actions · Answer 6

Hi All,

when we do any operation or transaction all are logged into log buffer.when you run the checkpoint save the all data to main database.

Regards
venkat

muthukkumaran Kaliyamoorthy SSCoach Points: 19026 More actions · Answer 7

kvr1985 (4/18/2011)
Hi All,
when we do any operation or transaction all are logged into log buffer.when you run the checkpoint save the all data to main database.

Couldn't understand the question?

Muthukkumaran Kaliyamoorthy
https://www.sqlserverblogforum.com/

kvr1985 SSCommitted Points: 1628 More actions · Answer 8

could you please explain that question.

Regards
venkat

Gail Shaw SSC Guru Points: 1004504 More actions · Answer 9

If you can clarify what you're asking, maybe. As it is, I don't understand the question.

Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

We walk in the dark places no others will enter
We stand on the bridge and no one may pass

Saravanan T SSCrazy Points: 2506 More actions · Answer 10

Hi Raghavender.

This link will help you :

You can get some info about Checkpoint , Lazywriter and Write Ahead Logging as well.

Regards,
Saravanan

M&M SSC-Insane Points: 21700 More actions · Answer 11

GilaMonster (4/14/2011)
They don't move. Data does not move from the log to the data file.
When a transaction occurs the data page is changed in memory and the log record is written to the log buffer. When the transaction commits, the log buffer is written to disk, to the transaction log (ldf). At some point after that the changed data page is written to the data file.
That's a massive simplification, but it's good enough.

This is a awesome simplication. We could as well save this one for our reference :).

M&M

2005_DBA Mr or Mrs. 500 Points: 524 More actions · Answer 12

Thanks Gila,

Simple enough to understand big process within SQL engine.