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HBase >> mail # dev >> hbase 0.94.0


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Re: hbase 0.94.0
The reason I brought it up is now that Mikhail committed the data block
encoding I was going to take a stab at adding the prefix trie encoding I
was working on this past summer.  My plan is to first make a minimally
invasive patch to prove correctness.  But, after that there will probably
be some big performance gains to be had from reworking some of the things
like KeyValueScanner which I would not have the courage to get working with
v1.

So, that was why I asked, but all of that is still more hypothetical than
real, and I don't even know if the first part will be done before branching
.94 at the end of February.  Makes sense to me to not delete v1 until
there's a good reason to, which it doesn't look like we have yet.  If I get
to the point where v1 is halting progress then we can reevaluate based on
more specific issues.  Maybe none of the prefix trie will even make .94...

..sent from my phone
On Jan 27, 2012 1:55 PM, "lars hofhansl" <[EMAIL PROTECTED]> wrote:

> Hey Jon,
>
> understood. Makes 0.94 hard, though. If we decide now to have a 0.90 to
> 0.94 upgrade path and then timing does not work out and nobody signs up for
> the testing because it 0.92 is more convenient we'd have gone through this
> for nothing.
>
> So... Thinking about this more I am -1 on supporting an official upgrade
> path other then from one release to the next.
> That said, we do not have to break things intentionally.
>
>
> I'm fine pushing HBASE-2600 and HFile v1 removal out of 0.94... As long as
> we won't havethe same argument for 0.96 :)
> And I am not aware of any file compatibility issues.
>
>
> We can also leave the 0.92 migration code in, but not officially support
> it as 0.90 to 0.94 path.
> Then CDH4 can make sure (if needed) that it is all working.
>
>
> Does that work for you guys?
>
> -- Lars
>
>
>
> ________________________________
>  From: Jonathan Hsieh <[EMAIL PROTECTED]>
> To: [EMAIL PROTECTED]; lars hofhansl <[EMAIL PROTECTED]>
> Sent: Friday, January 27, 2012 10:10 AM
> Subject: Re: hbase 0.94.0
>
>
> Lars,
>
> The upcoming CDH4 Beta HBase will be based on the latest hotness, 0.92.0.
> A CDH4 GA HBase will have to have an upgrade path from CDH3 HBase. If that
> HBase is 0.92 based, we'll test that, and if timing works out and we decide
> 0.94, we'll have to have a path (0.90->0.94) for than and will test that.
>
> HBASE-2600 is a big change of encoding of meta, while my understanding is
> that 0.90->0,92 is a graceful HFile format conversion.  Are there are
> things currently in trunk that further break compatiblity of the file
> format? (what jiras?)
>
> Jon.
>
>
> On Fri, Jan 27, 2012 at 9:16 AM, lars hofhansl <[EMAIL PROTECTED]>
> wrote:
>
> Not removing code for upgrade is fine.
> >
> >Todd, is Cloudera signing up for testing this path (0.90 to 0.94)?
> >
> >
> >Stack, what's your feeling w.r.t. to HBASE-2600, will keeping the 0.90 ->
> 0.92 migration path
> >make the migration code for HBASE-2600 (much) more complicated in 0.94?
> >
> >
> >-- Lars
> >
> >
> >
> >----- Original Message -----
> >From: Stack <[EMAIL PROTECTED]>
> >To: [EMAIL PROTECTED]
> >Cc:
> >Sent: Friday, January 27, 2012 9:02 AM
> >Subject: Re: hbase 0.94.0
> >
> >
> >On Fri, Jan 27, 2012 at 8:42 AM, Stack <[EMAIL PROTECTED]> wrote:
> >> In this particular case, there was no explicit migration step needed
> >> going 0.90 to 0.92.  Upgrading from 0.90 to 0.94 should just be
> >> running the 0.92 to 0.94 migration script (if there is one).
> >>
> >
> >Thinking more, the above only really holds if we keep the .META.
> >migration code that runs in 0.92 on startup on into 0.94 (I have a
> >patch here where I'm removing it... I should put this bit of code
> >back).
> >
> >I see Todd that you vote against removing hfile v1 in 0.94.  To make
> >going from CDH3 to CDH4, we should not purge any migrating code or old
> >version support.
> >
> >I'd be fine w/ that.  We'll need to work hard to ensure it taking it
> >on as a principal for 0.94.  Ok w/ you "Iron Hand" Lars?