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https://issues.apache.org/jira/browse/CASSANDRA-1207?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12880397#action_12880397
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Jonathan Ellis commented on CASSANDRA-1207:
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i'm skeptical that reading an index block's worth of columns is cheaper than
reading a bloom filter, even for skinny rows
(the main reason we have bloom filters is because in update-heavy workloads we
will have lots of row versions, most of which only have a few columns, so when
we are requesting specific column names we want to reject rows that don't have
that column at all as early as we can)
> Don't write BloomFilters for skinny rows
> ----------------------------------------
>
> Key: CASSANDRA-1207
> URL: https://issues.apache.org/jira/browse/CASSANDRA-1207
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Stu Hood
> Priority: Critical
> Fix For: 0.7
>
> Attachments:
> 0001-Return-alwaysMatchingBloomFilter-for-0-length-filter.patch,
> 0002-Conditionally-write-the-row-bloom-filter.patch
>
>
> All rows currently contain a serialized BloomFilter, regardless of size. For
> smaller rows, it is much more efficient in space and CPU time to not write a
> BloomFilter, and to eagerly perform lookups against the existing columns.
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