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https://issues.apache.org/jira/browse/HBASE-6014?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13289070#comment-13289070
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Todd Lipcon commented on HBASE-6014:
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Hey Kannan. You're exactly right on both cases. I'm not certain if this is a
huge win yet - it's probably only helpful on some very specific workloads. So,
we're not prioritizing it here. But really curious to hear if you think there
are some applications at FB that would benefit.
> Support for block-granularity bitmap indexes
> --------------------------------------------
>
> Key: HBASE-6014
> URL: https://issues.apache.org/jira/browse/HBASE-6014
> Project: HBase
> Issue Type: New Feature
> Components: regionserver
> Reporter: Todd Lipcon
> Attachments: 6014-bitmap-hacking.txt, bitmap-hacking.txt
>
>
> This came up in a discussion with Kannan today, so I promised to write
> something brief on JIRA -- this was suggested as a potential summer intern
> project. The idea is as follows:
> We have several customers who periodically run full table scan MR jobs
> against large HBase tables while applying fairly restrictive predicates. The
> predicates are often reasonably simple boolean expressions across known
> columns, and those columns often are enum-typed or otherwise have a fairly
> restricted range of values. For example, a real time process may mark rows as
> dirty, and a background MR job may scan for dirty rows in order to perform
> further processing like rebuilding inverted indexes.
> One way to speed up this type of query is to add bitmap indexes. In the
> context of HBase, I would envision this as a new type of metadata block
> included in the HFile which has a series of tuples: (qualifier, value range,
> compressed bitmap). A 1 bit in the bitmap indicates that the corresponding
> HFile block has at least one cell for which a column with the given qualifier
> falls within the given range. Queries which have an equality or comparison
> predicate against an indexed qualifier can then use the bitmap index to seek
> directly to those blocks which may contain relevant data.
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