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https://issues.apache.org/jira/browse/HBASE-13071?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14541822#comment-14541822
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Hadoop QA commented on HBASE-13071:
-----------------------------------
{color:red}-1 overall{color}. Here are the results of testing the latest
attachment
http://issues.apache.org/jira/secure/attachment/12732546/Releasenote-13071.txt
against master branch at commit 220ac141bfcea7798faa5f73295ec61d8b173af9.
ATTACHMENT ID: 12732546
{color:green}+1 @author{color}. The patch does not contain any @author
tags.
{color:green}+0 tests included{color}. The patch appears to be a
documentation, build,
or dev-support patch that doesn't require tests.
{color:red}-1 patch{color}. The patch command could not apply the patch.
Console output:
https://builds.apache.org/job/PreCommit-HBASE-Build/14035//console
This message is automatically generated.
> 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,
> HBASE-13071_trunk_rebase_1.0.patch, HBASE-13071_trunk_rebase_2.0.patch,
> HBaseStreamingScanDesign.pdf, HbaseStreamingScanEvaluation.pdf,
> HbaseStreamingScanEvaluationwithMultipleClients.pdf, Releasenote-13071.txt,
> gc.delay.png, gc.eshcar.png, gc.png, hits.delay.png, hits.eshcar.png,
> hits.png, latency.delay.png, latency.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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