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From "Gopal V (JIRA)" <>
Subject [jira] [Commented] (HIVE-9188) BloomFilter support in ORC
Date Sat, 07 Feb 2015 00:00:40 GMT


Gopal V commented on HIVE-9188:

+1- LGTM.

There are some perf corner cases, but they can be taken up in a later improvement cycle.

> BloomFilter support in ORC
> --------------------------
>                 Key: HIVE-9188
>                 URL:
>             Project: Hive
>          Issue Type: New Feature
>          Components: File Formats
>    Affects Versions: 0.15.0
>            Reporter: Prasanth Jayachandran
>            Assignee: Prasanth Jayachandran
>              Labels: orcfile
>         Attachments: HIVE-9188.1.patch, HIVE-9188.10.patch, HIVE-9188.11.patch, HIVE-9188.2.patch,
HIVE-9188.3.patch, HIVE-9188.4.patch, HIVE-9188.5.patch, HIVE-9188.6.patch, HIVE-9188.7.patch,
HIVE-9188.8.patch, HIVE-9188.9.patch
> BloomFilters are well known probabilistic data structure for set membership checking.
We can use bloom filters in ORC index for better row group pruning. Currently, ORC row group
index uses min/max statistics to eliminate row groups (stripes as well) that do not satisfy
predicate condition specified in the query. But in some cases, the efficiency of min/max based
elimination is not optimal (unsorted columns with wide range of entries). Bloom filters can
be an effective and efficient alternative for row group/split elimination for point queries
or queries with IN clause.

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