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From "Eshcar Hillel (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-13071) Hbase Streaming Scan Feature
Date Wed, 18 Mar 2015 07:21:41 GMT

    [ https://issues.apache.org/jira/browse/HBASE-13071?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14366767#comment-14366767
] 

Eshcar Hillel commented on HBASE-13071:
---------------------------------------

Yes it's all about setting the delays, but I don't want to change  them to make the results
look better.They are there just to make the point.

      From: Edward Bortnikov (JIRA) <jira@apache.org>
 To: eshcar@yahoo-inc.com 
 Sent: Monday, March 16, 2015 7:52 AM
 Subject: [jira] [Commented] (HBASE-13071) Hbase Streaming Scan Feature
   

    [ https://issues.apache.org/jira/browse/HBASE-13071?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14362777#comment-14362777
] 

Edward Bortnikov commented on HBASE-13071:
------------------------------------------

Eshcar,
Do you have an idea why there are still steps in the async graph? This probably means that
our delays are not long enough. 
Eddie 


    On Monday, March 16, 2015 1:14 AM, Eshcar Hillel (JIRA) <jira@apache.org> wrote:
  

 
    [ https://issues.apache.org/jira/browse/HBASE-13071?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Eshcar Hillel updated HBASE-13071:
----------------------------------
    Attachment: HBASE-13071_trunk_10.patch




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> Hbase Streaming Scan Feature
> ----------------------------
>
>                 Key: HBASE-13071
>                 URL: https://issues.apache.org/jira/browse/HBASE-13071
>             Project: HBase
>          Issue Type: New Feature
>            Reporter: Eshcar Hillel
>         Attachments: 99.eshcar.png, HBASE-13071_98_1.patch, HBASE-13071_trunk_1.patch,
HBASE-13071_trunk_10.patch, HBASE-13071_trunk_2.patch, HBASE-13071_trunk_3.patch, HBASE-13071_trunk_4.patch,
HBASE-13071_trunk_5.patch, HBASE-13071_trunk_6.patch, HBASE-13071_trunk_7.patch, HBASE-13071_trunk_8.patch,
HBASE-13071_trunk_9.patch, HBaseStreamingScanDesign.pdf, HbaseStreamingScanEvaluation.pdf,
HbaseStreamingScanEvaluationwithMultipleClients.pdf, gc.eshcar.png, hits.eshcar.png, network.png
>
>
> A scan operation iterates over all rows of a table or a subrange of the table. The synchronous
nature in which the data is served at the client side hinders the speed the application traverses
the data: it increases the overall processing time, and may cause a great variance in the
times the application waits for the next piece of data.
> The scanner next() method at the client side invokes an RPC to the regionserver and then
stores the results in a cache. The application can specify how many rows will be transmitted
per RPC; by default this is set to 100 rows. 
> The cache can be considered as a producer-consumer queue, where the hbase client pushes
the data to the queue and the application consumes it. Currently this queue is synchronous,
i.e., blocking. More specifically, when the application consumed all the data from the cache
--- so the cache is empty --- the hbase client retrieves additional data from the server and
re-fills the cache with new data. During this time the application is blocked.
> Under the assumption that the application processing time can be balanced by the time
it takes to retrieve the data, an asynchronous approach can reduce the time the application
is waiting for data.
> We attach a design document.
> We also have a patch that is based on a private branch, and some evaluation results of
this code.



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