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HBase >> mail # dev >> DISCUSS : HFile V3 proposal for tags in 0.96


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ramkrishna vasudevan 2013-07-18, 17:14
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Ted Yu 2013-07-18, 17:23
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Jimmy Xiang 2013-07-18, 17:55
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ramkrishna vasudevan 2013-07-19, 04:29
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Ted Yu 2013-07-19, 04:40
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ramkrishna vasudevan 2013-07-19, 04:57
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Ted Yu 2013-07-19, 05:00
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Stack 2013-07-19, 05:12
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Jean-Marc Spaggiari 2013-07-19, 11:02
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ramkrishna vasudevan 2013-07-19, 11:11
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Jean-Marc Spaggiari 2013-07-19, 11:23
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Anoop John 2013-07-19, 11:51
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ramkrishna vasudevan 2013-07-19, 12:00
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Jean-Marc Spaggiari 2013-07-19, 13:09
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Ted Yu 2013-07-19, 14:18
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Re: DISCUSS : HFile V3 proposal for tags in 0.96
It should be Ted. Tags will be present in KV(Cell).  So whichever part
deals with KVs (Cells) can use the tags and do some thing with that.  Do
some checks in Filter and filter out KVs, or access in CP etc etc.

-Anoop-

On Fri, Jul 19, 2013 at 7:48 PM, Ted Yu <[EMAIL PROTECTED]> wrote:

> Would tags be visible to methods of BaseRegionObserver, other than
> AccessController ?
>
> Meaning, would other (non-secure) components of HBase be able to use cell
> tagging to store certain information ?
>
> Please clarify.
>
> Thanks
>
> On Fri, Jul 19, 2013 at 6:09 AM, Jean-Marc Spaggiari <
>  [EMAIL PROTECTED]> wrote:
>
> > Thanks Ram and Anoop for those details again. I don't think there is a
> need
> > to be able to revert from V3 to V2. And 1 byte overhead on an HFile is
> not
> > really an overhead. As Anoop proposed, if there is a way to de-activate
> the
> > tags feature when all the KVs in a file are having tag length as zero,
> then
> > it's all good!
> >
> > Looking forward to test that!
> >
> > JM
> >
> > 2013/7/19 ramkrishna vasudevan <[EMAIL PROTECTED]>
> >
> > > But am afraid that once the user switches to V3 with tags he cannot
> come
> > > back to V2.  If this scenario is possible then we need to see a work
> > around
> > > for that?
> > > Particularly in the case if the user has written the tags and tries to
> > read
> > > it back with V2 then it would not work.
> > >
> > > If user switches to V3 but does not write any tags then if we go with
> the
> > > option of making tags optional using the Fileinfo then atleast after
> the
> > > compaction is done the Hfile could be read with the V2 reader also.
>  But
> > i
> > > don't think the user would intend to do this given the fact that he
> needs
> > > tags for his usecase.
> > >
> > > Regards
> > > Ram
> > >
> > >
> > > On Fri, Jul 19, 2013 at 5:21 PM, Anoop John <[EMAIL PROTECTED]>
> > wrote:
> > >
> > > > Jean
> > > >         When V2 will be used there wont any extra bytes and so no
> > > overhead
> > > > in write or read paths.
> > > > When V3 is used, and there are no tags present at all, we will have
> > extra
> > > > bytes for writing tag length.  Trying to put tag length as VInt so
> that
> > > > this will be 1 byte only.  Then using File infos we can avoid
> overhead.
> > > >
> > > > Say when all the KVs in a file are having tag length as zero( a filer
> > > > trailer indicate this) , during read we can avoid the read and decode
> > of
> > > > teh tag length. Just skip one byte of tag length.
> > > >
> > > > Regarding avoiding the tag length (even the 1 byte fully)  maybe
> during
> > > > compaction it should be possible. But whether really needed I am
> > > thinikng.
> > > > User can select V3 when there is a need for Tags.
> > > >
> > > > -Anoop-
> > > >
> > > > On Fri, Jul 19, 2013 at 4:53 PM, Jean-Marc Spaggiari <
> > > > [EMAIL PROTECTED]> wrote:
> > > >
> > > > > Thanks Ram.
> > > > >
> > > > > One last. Space wise. If I understand correctly, between V2 and V3,
> > > when
> > > > > tags are de-activated, there will be only a 1 bit difference, so
> same
> > > > > storage space used. If tags are activated but empty, is it going to
> > be
> > > > the
> > > > > same thing? Or are we going to have all the tags overhead? Like can
> > we
> > > > have
> > > > > a byte to say "no tags in that file" in addition to "tags are
> > activated
> > > > for
> > > > > that file"?
> > > > >
> > > > > So 2 questions.
> > > > >
> > > > > 1) what the overhead on disk space from the tags.
> > > > > 2) should we have a flag(bit) per file to say no tags even if
> > activated
> > > > to
> > > > > limit this overhead and ket people activate it for futur uses?
> > > > >
> > > > > JMS
> > > > > Le 2013-07-19 07:11, "ramkrishna vasudevan" <
> > > > > [EMAIL PROTECTED]> a écrit :
> > > > >
> > > > > > >>Based on your details, I think it will be, but very minimal, or
> > > > > > almost invisible, correct?
> > > > > > Yes of course.
> > > > > > Regarding migration, any file written with V2 would still be read
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ramkrishna vasudevan 2013-07-19, 15:05
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Andrew Purtell 2013-07-19, 16:27
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Ted Yu 2013-07-19, 16:32
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Anoop John 2013-07-19, 17:13
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Ted Yu 2013-07-19, 17:35
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Elliott Clark 2013-07-19, 17:52
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Andrew Purtell 2013-07-19, 18:01
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Elliott Clark 2013-07-19, 21:02
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Andrew Purtell 2013-07-19, 22:34
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Stack 2013-07-19, 23:31
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ramkrishna vasudevan 2013-07-20, 02:10
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Andrew Purtell 2013-07-22, 17:23
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Jean-Marc Spaggiari 2013-07-23, 22:43
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Andrew Purtell 2013-07-24, 17:33
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ramkrishna vasudevan 2013-07-25, 18:09
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Andrew Purtell 2013-07-19, 16:48
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Ted Yu 2013-07-24, 17:30
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Andrew Purtell 2013-07-19, 16:25