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From "Vandana Ayyalasomayajula (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-9343) Implement stateless scanner for Stargate
Date Thu, 16 Jan 2014 19:15:28 GMT

    [ https://issues.apache.org/jira/browse/HBASE-9343?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13873800#comment-13873800
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Vandana Ayyalasomayajula commented on HBASE-9343:
-------------------------------------------------

[~jxiang] -- I currently have the default limit to Integer.MAX, I can change it to some good
value. I can take that up as a dependent JIRA. What do you think a good value is ? We send
the rows lazily to the client, so server being OOM is less likely issue. Even in that case,
the client can resend the request with updated scan parameters, so that scanning can be continued.


> Implement stateless scanner for Stargate
> ----------------------------------------
>
>                 Key: HBASE-9343
>                 URL: https://issues.apache.org/jira/browse/HBASE-9343
>             Project: HBase
>          Issue Type: Improvement
>          Components: REST
>    Affects Versions: 0.94.11
>            Reporter: Vandana Ayyalasomayajula
>            Assignee: Vandana Ayyalasomayajula
>            Priority: Minor
>             Fix For: 0.98.1, 0.99.0
>
>         Attachments: HBASE-9343_94.00.patch, HBASE-9343_94.01.patch, HBASE-9343_trunk.00.patch,
HBASE-9343_trunk.01.patch, HBASE-9343_trunk.01.patch, HBASE-9343_trunk.02.patch, HBASE-9343_trunk.03.patch,
HBASE-9343_trunk.04.patch, HBASE-9343_trunk.05.patch
>
>
> The current scanner implementation for scanner stores state and hence not very suitable
for REST server failure scenarios. The current JIRA proposes to implement a stateless scanner.
In the first version of the patch, a new resource class "ScanResource" has been added and
all the scan parameters will be specified as query params. 
> The following are the scan parameters
> startrow -  The start row for the scan.
> endrow - The end row for the scan.
> columns - The columns to scan. 
> starttime, endtime - To only retrieve columns within a specific range of version timestamps,both
start and end time must be specified.
> maxversions  - To limit the number of versions of each column to be returned.
> batchsize - To limit the maximum number of values returned for each call to next().
> limit - The number of rows to return in the scan operation.
>  More on start row, end row and limit parameters.
> 1. If start row, end row and limit not specified, then the whole table will be scanned.
> 2. If start row and limit (say N) is specified, then the scan operation will return N
rows from the start row specified.
> 3. If only limit parameter is specified, then the scan operation will return N rows from
the start of the table.
> 4. If limit and end row are specified, then the scan operation will return N rows from
start of table till the end row. If the end row is 
> reached before N rows ( say M and M &lt; N ), then M rows will be returned to the
user.
> 5. If start row, end row and limit (say N ) are specified and N &lt; number of rows
between start row and end row, then N rows from start row
> will be returned to the user. If N &gt; (number of rows between start row and end
row (say M), then M number of rows will be returned to the
> user.



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