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From "HBase Review Board (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HBASE-2793) Add ability to extract a specified list of versions of a column in a single roundtrip
Date Thu, 08 Jul 2010 06:40:52 GMT

    [ https://issues.apache.org/jira/browse/HBASE-2793?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12886258#action_12886258
] 

HBase Review Board commented on HBASE-2793:
-------------------------------------------

Message from: "Kannan Muthukkaruppan" <kannan@facebook.com>


bq.  On 2010-07-07 15:03:56, Ryan Rawson wrote:
bq.  > trunk/src/main/java/org/apache/hadoop/hbase/filter/TimestampsFilter.java, line 26
bq.  > <http://review.hbase.org/r/268/diff/2/?file=2118#file2118line26>
bq.  >
bq.  >     by default if somehow the minTimeStamp gets kept as 0 with an empty timestamps
list, then it will filter _everything out_.  Do you want to set this to 0 and instead include
everything by default?  Might make it easier to debug perhaps?
bq.  >

Ryan: If TimestampsFilter is used, but client passes an empty list of timestamps, the semantics
I am aiming for is indeed to filter everything out. That's why I am setting this MAX_VALUE.
The TimestampsFilter is like an IN list predicate in SQL.

...
WHERE timestamp_col IN (t1, t2, ... t3)

If the IN list is empty, no rows should be returned.


bq.  On 2010-07-07 15:03:56, Ryan Rawson wrote:
bq.  > trunk/src/main/java/org/apache/hadoop/hbase/regionserver/ScanQueryMatcher.java,
line 25
bq.  > <http://review.hbase.org/r/268/diff/2/?file=2119#file2119line25>
bq.  >
bq.  >     i dont think this import is necessary...

yes, my previous version of the patch needed it. I'll remove it.


bq.  On 2010-07-07 15:03:56, Ryan Rawson wrote:
bq.  > trunk/src/main/java/org/apache/hadoop/hbase/regionserver/ScanQueryMatcher.java,
line 27
bq.  > <http://review.hbase.org/r/268/diff/2/?file=2119#file2119line27>
bq.  >
bq.  >     nor this one

ditto. Will remove.


- Kannan


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> Add ability to extract a specified list of versions of a column in a single roundtrip
> -------------------------------------------------------------------------------------
>
>                 Key: HBASE-2793
>                 URL: https://issues.apache.org/jira/browse/HBASE-2793
>             Project: HBase
>          Issue Type: New Feature
>            Reporter: Kannan Muthukkaruppan
>            Assignee: Kannan Muthukkaruppan
>         Attachments: 2793_patch_v1.txt, 2793_patch_v2.txt
>
>
> In one of the use cases we were looking at, each row contains a single column, but with
several versions (e.g., each version representing an event in a log), and we want to be able
to extract specific set of versions from the row in a single round-trip.
> Currently, on a Get, one can retrieve a specific version of a column using setTimeStamp(ts)
or a range of versions using setTimeRange(min, max). But not a set of specified versions.
It would be useful to add this ability.

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