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From "stack (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HBASE-792) Rewrite getClosestAtOrJustBefore; doesn't scale as currently written
Date Wed, 03 Jun 2009 23:48:08 GMT

     [ https://issues.apache.org/jira/browse/HBASE-792?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

stack updated HBASE-792:
------------------------

    Fix Version/s:     (was: 0.20.0)

Moving out of 0.20.0.  Not going to happen unless its already done as part of hbase-1304 (haven't
heard).

> Rewrite getClosestAtOrJustBefore; doesn't scale as currently written
> --------------------------------------------------------------------
>
>                 Key: HBASE-792
>                 URL: https://issues.apache.org/jira/browse/HBASE-792
>             Project: Hadoop HBase
>          Issue Type: Bug
>            Reporter: stack
>            Priority: Blocker
>         Attachments: 792.patch
>
>
> As currently written, as a table gets bigger, the number of rows .META. needs to keep
count of grows.
> As written, our getClosestAtOrJustBefore, goes through every storefile and in each picks
up any row that could be a possible candidate for closest before.  It doesn't just get the
closest from the storefile, but all keys that are closest before.  Its not selective because
how can it tell at the store file level which of the candidates will survive deletes that
are sitting in later store files or up in memcache.
> So, if a store file has keys 0-10 and we ask to get the row that is closest or just before
7, it returns rows 0-7.. and so on per store file.
> Can bet big and slow weeding key wanted.

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