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From lars hofhansl <la...@apache.org>
Subject Re: best read path explanation
Date Mon, 14 Jan 2013 22:59:46 GMT
This in enforced in the serverside scanner framework (ScanQueryMatcher called by StoreScanner).
So while expired KeyValues are only physically only removed once a compaction runs, they are
logically hidden by the scanner framework.
In fact the same scanner framework is used to decide whether KeyValues are visible to a user
scan or during a compaction.


As for Ahmed's question, you can run the tests locally by just applying the patch to a svn
checkout (I doubt it will still apply, though).


-- Lars



________________________________
 From: Asaf Mesika <asaf.mesika@gmail.com>
To: "user@hbase.apache.org" <user@hbase.apache.org> 
Cc: lars hofhansl <larsh@apache.org> 
Sent: Monday, January 14, 2013 10:47 AM
Subject: Re: best read path explanation
 

I have a follow up question here: 
A column family can be defined to have a maximum number of versions per column qualifier value.
Is this enforced only by the client side code (HTable) or also by the InternalScanner implementations?

On Monday, January 14, 2013, S Ahmed  wrote:

Thanks Lars!
>
>Sort of a side question after following your proposed patch:
>https://issues.apache.org/jira/secure/attachment/12511771/5268-v5.txt
>
>Locally on your computer (laptop?), can those tests run in isolation or you
>need a fairly complicated setup to run them? (all the various hbase
>dependancies like zookeeper etc).
>
>
>On Sun, Jan 13, 2013 at 9:33 PM, lars hofhansl <larsh@apache.org> wrote:
>
>> Does this help:
>> http://hadoop-hbase.blogspot.com/2012/01/scanning-in-hbase.html ?
>>
>>
>>
>>
>> ________________________________
>>  From: S Ahmed <sahmed1020@gmail.com>
>> To: user@hbase.apache.org
>> Sent: Sunday, January 13, 2013 7:24 AM
>> Subject: best read path explanation
>>
>> What is the best hbase read path explanation?
>>
>> I understand that hbase stores data and doesn't allow for mutations, so I'm
>> confused as to how a read can get the latest data?
>>
>> I'm guessing there are merges done between the immutable file stores, and
>> in-memory stores?
>>
>
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