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From Stack <st...@duboce.net>
Subject Re: Pull instant schema updating out?
Date Tue, 03 Apr 2012 16:49:05 GMT
On Tue, Apr 3, 2012 at 9:23 AM, Ted Yu <yuzhihong@gmail.com> wrote:
> Has any change been done in the past half year on "Online schema update" ?
>

Minor if any.

It does have the advantage that it is at least being used.


> When we make such an important decision, we should evaluate various
> factors. "Instant schema alter" has better design: it endures master
> failover.
>
> If the following tests can be written for "Online schema update" and pass,
> I would vote for it:
> src/test/java/org/apache/hadoop/hbase/client/TestInstantSchemaChange.java
> src/test/java/org/apache/hadoop/hbase/client/TestInstantSchemaChangeFailover.java
> src/test/java/org/apache/hadoop/hbase/client/TestInstantSchemaChangeSplit.java
>
> Otherwise I am -1 on pulling "Instant schema alter"
>
> There is more work to be done: reduce the noise posed by MonitoredTask,
> throttling, etc. But these are not difficult tasks.
>

It has 'better' design but it is fallible to failure still and far
from perfect in that it persists by writing feature-particular znodes
w/ feature-particular custom handlers sprinkled about the code base.
We should be able to do better.

All of your above argument is posited on more work being done whether
tests for one implementation or completion of a feature no one has
used in almost a year.   I would suggest that you don't have much of a
case if it is predicated on the work of others.  Sign up to fix it or
lets pull it; even then I'd say pull it till its fixed rather than let
a broke implementation go out in 0.94.

St.Ack

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