Guys,

When running examples, you bring them into HDFS. Say, you need to make some correction to a file, you need to make them on local FS and run $hadoop fs -put ... again. You cannot just make changes to files inside HDFS except for "touchz" a file, correct?

Just making sure.

Thnx,
AK
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Files are immutable, once written into the Hdfs. And touchz creates a file
of 0 length.

Regards,
    Mohammad Tariq

On Fri, Nov 9, 2012 at 3:18 AM, Kartashov, Andy <[EMAIL PROTECTED]>wrote:

> Guys,
>
> When running examples, you bring them into HDFS. Say, you need to make
> some correction to a file, you need to make them on local FS and run
> $hadoop fs -put ... again. You cannot just make changes to files inside
> HDFS except for "touchz" a file, correct?
>
> Just making sure.
>
> Thnx,
> AK
> NOTICE: This e-mail message and any attachments are confidential, subject
> to copyright and may be privileged. Any unauthorized use, copying or
> disclosure is prohibited. If you are not the intended recipient, please
> delete and contact the sender immediately. Please consider the environment
> before printing this e-mail. AVIS : le présent courriel et toute pièce
> jointe qui l'accompagne sont confidentiels, protégés par le droit d'auteur
> et peuvent être couverts par le secret professionnel. Toute utilisation,
> copie ou divulgation non autorisée est interdite. Si vous n'êtes pas le
> destinataire prévu de ce courriel, supprimez-le et contactez immédiatement
> l'expéditeur. Veuillez penser à l'environnement avant d'imprimer le présent
> courriel
>

What do you mean immutable? Do u mean non modifiable maybe .?  Immutable implies that they can't be deleted .

Jay Vyas
MMSB
UCHC

On Nov 8, 2012, at 5:28 PM, Mohammad Tariq <[EMAIL PROTECTED]> wrote:

> Files are immutable, once written into the Hdfs. And touchz creates a file of 0 length.
>
> Regards,
>     Mohammad Tariq
>
>
>
> On Fri, Nov 9, 2012 at 3:18 AM, Kartashov, Andy <[EMAIL PROTECTED]> wrote:
>> Guys,
>>
>> When running examples, you bring them into HDFS. Say, you need to make some correction to a file, you need to make them on local FS and run $hadoop fs -put ... again. You cannot just make changes to files inside HDFS except for "touchz" a file, correct?
>>
>> Just making sure.
>>
>> Thnx,
>> AK
>> NOTICE: This e-mail message and any attachments are confidential, subject to copyright and may be privileged. Any unauthorized use, copying or disclosure is prohibited. If you are not the intended recipient, please delete and contact the sender immediately. Please consider the environment before printing this e-mail. AVIS : le présent courriel et toute pièce jointe qui l'accompagne sont confidentiels, protégés par le droit d'auteur et peuvent être couverts par le secret professionnel. Toute utilisation, copie ou divulgation non autorisée est interdite. Si vous n'êtes pas le destinataire prévu de ce courriel, supprimez-le et contactez immédiatement l'expéditeur. Veuillez penser à l'environnement avant d'imprimer le présent courriel
>

Apologies for the wrong word. Yes, I meant non modifiable.

Regards,
    Mohammad Tariq

On Fri, Nov 9, 2012 at 4:01 AM, Jay Vyas <[EMAIL PROTECTED]> wrote:

> What do you mean immutable? Do u mean non modifiable maybe .?  Immutable
> implies that they can't be deleted .
>
> Jay Vyas
> MMSB
> UCHC
>
> On Nov 8, 2012, at 5:28 PM, Mohammad Tariq <[EMAIL PROTECTED]> wrote:
>
> Files are immutable, once written into the Hdfs. And touchz creates a file
> of 0 length.
>
> Regards,
>     Mohammad Tariq
>
>
>
> On Fri, Nov 9, 2012 at 3:18 AM, Kartashov, Andy <[EMAIL PROTECTED]>wrote:
>
>> Guys,
>>
>> When running examples, you bring them into HDFS. Say, you need to make
>> some correction to a file, you need to make them on local FS and run
>> $hadoop fs -put ... again. You cannot just make changes to files inside
>> HDFS except for "touchz" a file, correct?
>>
>> Just making sure.
>>
>> Thnx,
>> AK
>> NOTICE: This e-mail message and any attachments are confidential, subject
>> to copyright and may be privileged. Any unauthorized use, copying or
>> disclosure is prohibited. If you are not the intended recipient, please
>> delete and contact the sender immediately. Please consider the environment
>> before printing this e-mail. AVIS : le présent courriel et toute pièce
>> jointe qui l'accompagne sont confidentiels, protégés par le droit d'auteur
>> et peuvent être couverts par le secret professionnel. Toute utilisation,
>> copie ou divulgation non autorisée est interdite. Si vous n'êtes pas le
>> destinataire prévu de ce courriel, supprimez-le et contactez immédiatement
>> l'expéditeur. Veuillez penser à l'environnement avant d'imprimer le présent
>> courriel
>>
>
>

Mohammad is right.
When you write a file to HDFS, it can´t be modified.
The pattern in HDFS is write-one/read-many-times.

If you want to use a distribution where you can read and write files, you should take a look
to MapR distribution.

----- Mensaje original -----
De: Mohammad Tariq <[EMAIL PROTECTED]>
Para: [EMAIL PROTECTED]
Enviado: Thu, 08 Nov 2012 17:33:56 -0500 (CST)
Asunto: Re: hadoop - running examples

Apologies for the wrong word. Yes, I meant non modifiable.

Regards,
    Mohammad Tariq

On Fri, Nov 9, 2012 at 4:01 AM, Jay Vyas <[EMAIL PROTECTED]> wrote:

> What do you mean immutable? Do u mean non modifiable maybe .?  Immutable
> implies that they can't be deleted .
>
> Jay Vyas
> MMSB
> UCHC
>
> On Nov 8, 2012, at 5:28 PM, Mohammad Tariq <[EMAIL PROTECTED]> wrote:
>
> Files are immutable, once written into the Hdfs. And touchz creates a file
> of 0 length.
>
> Regards,
>     Mohammad Tariq
>
>
>
> On Fri, Nov 9, 2012 at 3:18 AM, Kartashov, Andy <[EMAIL PROTECTED]>wrote:
>
>> Guys,
>>
>> When running examples, you bring them into HDFS. Say, you need to make
>> some correction to a file, you need to make them on local FS and run
>> $hadoop fs -put ... again. You cannot just make changes to files inside
>> HDFS except for "touchz" a file, correct?
>>
>> Just making sure.
>>
>> Thnx,
>> AK
>> NOTICE: This e-mail message and any attachments are confidential, subject
>> to copyright and may be privileged. Any unauthorized use, copying or
>> disclosure is prohibited. If you are not the intended recipient, please
>> delete and contact the sender immediately. Please consider the environment
>> before printing this e-mail. AVIS : le présent courriel et toute pièce
>> jointe qui l'accompagne sont confidentiels, protégés par le droit d'auteur
>> et peuvent être couverts par le secret professionnel. Toute utilisation,
>> copie ou divulgation non autorisée est interdite. Si vous n'êtes pas le
>> destinataire prévu de ce courriel, supprimez-le et contactez immédiatement
>> l'expéditeur. Veuillez penser à l'environnement avant d'imprimer le présent
>> courriel
>>
>
>
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On Thu, Nov 8, 2012 at 1:48 PM, Kartashov, Andy <[EMAIL PROTECTED]> wrote:
> When running examples, you bring them into HDFS. Say, you need to make some correction to a file, you need to make them on local FS and run $hadoop fs -put ... again. You cannot just make changes to files inside HDFS except for "touchz" a file, correct?

If you need to change existing data, you do need to write a new file,
or delete the old file then re-write it.  So as far as that goes, yes,
you cannot just make changes.

However, files can be appended to in HDFS, although I am not aware of
a "hdfs dfs -append" command to do append from the commandline. So
it's not quite correct to say that touchz is the only thing to change
an existing file.

-andy