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From "Bryan Duxbury (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HBASE-489) CellValue class for transporting cell timestamp with cell value simultaneously
Date Tue, 04 Mar 2008 20:29:40 GMT

    [ https://issues.apache.org/jira/browse/HBASE-489?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12575127#action_12575127
] 

Bryan Duxbury commented on HBASE-489:
-------------------------------------

I also agree that the immature software clause is our best protection. 

While it's not critical for 0.2, it is a really useful improvement, and it is best if we can
do it sooner than later. At the very least we could implement in at the layers lower than
the HTable API and pull it up later when its appropriate. Or, we could change the methods
to do what we want them to right away, and make new methods like getWithoutTimestamp that
are immediately deprecated, but give people a way to change their code minimally.

> CellValue class for transporting cell timestamp with cell value simultaneously
> ------------------------------------------------------------------------------
>
>                 Key: HBASE-489
>                 URL: https://issues.apache.org/jira/browse/HBASE-489
>             Project: Hadoop HBase
>          Issue Type: New Feature
>          Components: client, regionserver
>            Reporter: Bryan Duxbury
>            Priority: Minor
>             Fix For: 0.2.0
>
>
> All of the get* methods take a timestamp parameter that means "at least as old as X".
This is handy for getting data that fits your expectations about when it should exist. However,
the result you get back doesn't actually contain the real timestamp the cell was stored at.

> For example, let's say you write the stock price for your favorite company into row "YHOO"
at cell "stock:price". It takes the default timestamp of right now. Then, a day passes. You
want to get the most recent stock price for YHOO, and also when the price was gathered. In
the current system, you couldn't do this at all without also doing a scan at the same time.

> If we added a new class called CellValue that contained the byte[] cell value as well
as the long timestamp of when it was stored, we could return an instance of this class wherever
we used to return just the byte[]. This could be used in all the get() methods, getRow, getClosestAtOrBefore,
etc. This has the advantage of making timestamp into a first-class citizen in HBase, which
it hasn't been so far.
> Thoughts?

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