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Re: dbv

From: yong huang <>
Date: Mon, 2 Oct 2000 14:48:54 -0700 (PDT)
Message-Id: <>

Question: can dbv be used on an online datafile?

A few days ago, I asked Renato where he got the information that dbverify can be used on online datafiles in UNIX but not in Windows. He says by reading manuals and experiment. Other people say it can be used on online datafiles in UNIX because UNIX allows you to read a file while it's open by another process (to that effect), while Windows does not. I have some doubt since the Oracle manual says:

DBVERIFY is an external command-line utility that performs a physical data structure integrity check on an offline database

But Metalink Note:35512.1 says:

On UNIX systems DBV can be run against datafiles which are currently opened by a database instance - there is no need to shutdown the database. Datafiles are opened read-only by DBV so it cannot corrupt the contents.

I don't worry about corrupting the datafile. I just question the accuracy of the result when you run it on online files, such as false positive or false negative. I talked to my coworker. He has a good point that "in a busy database the file header might not be sync'd with the data blocks in it and it might be ideal to run dbv in an 'offline' database". I'm afraid dbv will not make sure the file header and data blocks are sync'ed as he suspects. Whether the database is busy or not in this regard depends on its waits on db file single write (for writing file headers) and db file parallel write (for writing content), I think.

Anybody has more thoughts on this?


-----Original Message-----
> From:
> Date: Thu, 28 Sep 2000 09:01:04 +1100
> Subject: Re: DBVERIFY
> Apart from reading the manuals when i'm in the toilet (g:) it is really by
> trying it out.
> cheers
> R

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