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https://issues.apache.org/jira/browse/HBASE-696?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12611846#action_12611846
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Jim Kellerman commented on HBASE-696:
-------------------------------------
> -----Original Message-----
> From: Jim Kellerman
> Sent: Tuesday, July 08, 2008 4:31 PM
> To: hbase-user
> Subject: RE: HBASE-696 Make bloomfilter true/false and self-sizing
>
> Unless there is significant feedback to the contrary, making
> bloom filters true/false and self sizing will be an
> incompatible change.
>
> During migration, columns which have bloom filters enabled
> currently will have the bloom filter erased and disabled.
>
> Columns may bloom filters only if they are enabled when the
> column is created.
>
> If a column is later modified to disable the bloom filter, it
> will be erased and cannot be re-enabled.
>
> There is one short term (0.2.0) option for migration and
> enabling bloom filters which will be very expensive: reading
> the column twice, first to establish the number of entries
> that are needed and second, to create the bloom filter.
>
> There is one long term option: convince Hadoop that MapFile
> should be subclassable which would entail changing private
> members to protected members, or to provide accessors to the
> private members in MapFile. Because hadoop-0.18.0 is in
> feature freeze, any change of this sort would have to wait
> for hadoop-0.19.0. hbase-0.3.0 will target hadoop-0.18.x, so
> this change would have to wait until hbase-0.4.0.
>
> The question is how many people use bloom filters today? It
> is our belief that they are not particularly useful as
> implemented. If you do use bloom filters today, would you
> object to a process by which you would create a new bloom
> filter enabled column and copy your data to the new column?
>
> ---
> Jim Kellerman, Senior Engineer; Powerset
> Make bloomfilter true/false and self-sizing
> -------------------------------------------
>
> Key: HBASE-696
> URL: https://issues.apache.org/jira/browse/HBASE-696
> Project: Hadoop HBase
> Issue Type: Improvement
> Reporter: stack
> Assignee: Jim Kellerman
> Fix For: 0.2.0
>
>
> Remove bloomfilter options. Only one bloomfilter type makes sense in hbase
> context. Also, make bloomfilter self-sizing; you know size when flushing.
> Putting in 0.2 for now because its API change (for the simpler). We can punt
> later.
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