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HBase, mail # user - Problem deleting neighboors with timestamp=0


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Re: Problem deleting neighboors with timestamp=0
anil gupta 2012-11-19, 07:44
Hi Chris,

My two cents...
IMHO, onus of ensuring the right Timestamp value should always be on the
application logic rather than HBase. Essentially, timestamp is long number
in HBase. So, Timestamp with value of '0' seems to be a valid value. What
if someone really wants to use the value 0 as timestamp? HBase is used by a
variety of users in quite different use cases. So, i dont think it would be
a good idea of introducing this restriction.

HTH,
Anil
On Sun, Nov 18, 2012 at 9:45 PM, Chris Larsen <[EMAIL PROTECTED]>wrote:

> > So you mean that you have explicitly set the timestamp to 0 for the
> column
> which you did not want to delete?
>
> Yes, my code was setting the timestamp explicitly to 0. I fixed that bug in
> my code (since I do want a valid timestamp) but I was wondering if a
> timestamp of 0 is "legal" and if it isn't, maybe HBase should kick back
> errors if someone tries it.
>
> -----Original Message-----
> From: ramkrishna vasudevan [mailto:[EMAIL PROTECTED]]
> Sent: Sunday, November 18, 2012 11:31 PM
> To: [EMAIL PROTECTED]
> Subject: Re: Problem deleting neighboors with timestamp=0
>
> Hi Chris
>
> So you mean that you have explicitly set the timestamp to 0 for the column
> which you did not want to delete?
>
> Regards
> Ram
>
> On Mon, Nov 19, 2012 at 1:44 AM, Chris Larsen
> <[EMAIL PROTECTED]>wrote:
>
> > Hello, I was going nuts over an issue where I would try to delete a
> > single column but a neighboring column (sorted by the column names in
> > bytes) was also being deleted because, I found out, the timestamp for
> > the neighbor was set to 0. Here are some of the columns in the row
> > (taken from the shell
> > utility)
> >
> >
> >
> > hbase(main):002:0> get 'mytable',
> > "\x00\x01\xAA\x50\x8E\xC4\x20\x00\x00\x01\x00\x00\xAC"
> >
> > COLUMN                                  CELL
> >
> > t:\x00\x17                             timestamp=1351533601998,
> > value=\x00\x00\x00\x00O\xB2\xDC[
> >
> > t:\x00\x17\x03\xD7\x...(long name)     timestamp=0, value=\x00\x00\x...
> > lots
> > of binary data....
> >
> > t:\x03\xD7                             timestamp=1351533661458,
> > value=\x00\x00\x00\x00O\xB9\xD1\xE5
> >
> > t:\x07\x97                             timestamp=1351533721758,
> > value=\x00\x00\x00\x00O\xBC#\xD0
> >
> > t:\x0BW                                timestamp=1351533781738,
> > value=\x00\x00\x00\x00O\xBD\xB93
> >
> >
> >
> > I wanted to delete the column "t:\x00\x17" but every time I did, the
> > column "t:\x00\x17\x03\xD7\x..." would also be deleted so that I'd wind
> up
> with:
> >
> >
> >
> > hbase(main):005:0> get 'mytable',
> > "\x00\x01\xAA\x50\x8E\xC4\x20\x00\x00\x01\x00\x00\xAC"
> >
> > COLUMN                                  CELL
> >
> > t:\x03\xD7                             timestamp=1351533661458,
> > value=\x00\x00\x00\x00O\xB9\xD1\xE5
> >
> > t:\x07\x97                             timestamp=1351533721758,
> > value=\x00\x00\x00\x00O\xBC#\xD0
> >
> > t:\x0BW                                timestamp=1351533781738,
> > value=\x00\x00\x00\x00O\xBD\xB93
> >
> >
> >
> > My JAVA code looked like this:
> >
> >
> >
> > HTableInterface table = factory.createHTableInterface(config,
> > "mytable".getBytes());
> >
> > Delete delete = new Delete(HexToBytes("0001AA508EC4200000010000AC"));
> >
> > delete.deleteColumn("t".getBytes(), new byte[] { (byte) 0x00, (byte)
> > 0x17 });
> >
> > table.delete(delete);
> >
> >
> >
> > as I was typing this out, I noticed that the column I didn't want to
> > delete had a timestamp of 0. I put the column back with a valid
> > timestamp and tried deleting the original column, and it worked
> > properly. I fixed my code to always provide a positive timestamp, but
> > my question is, are timestamps set to 0 valid for storing data in
> > HBase? And if so, then this may be a bug that needs addressing.
> > Thanks!
> >
> >
>
>
--
Thanks & Regards,
Anil Gupta