[jira] [Updated] (HBASE-6014) Support for block-granularity bitmap indexes

["Todd Lipcon (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HBASE-6014?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Todd Lipcon updated HBASE-6014:
-------------------------------

    Attachment: bitmap-hacking.txt

Oh, I also did some hacking on the airplane: this WIP patch adds:
- a cuckoo hashtable implementation which uses byte array ranges as keys. I needed this to avoid having to do copies into byte[] for use with a normal TreeMap. It could have been a normal separate-chaining Hashtable, but I've been wanting to implement a cuckoo hashmap for a while :)
- imports JavaEWAH, a compressed bitmap index library
- hooks into the HFile write path to write out bitmap index blocks with the hfile

obviously far from anything useful, but posting here in case anyone's interested in running with it
                
> 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: 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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