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https://issues.apache.org/jira/browse/CASSANDRA-8938?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14388881#comment-14388881
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Tyler Hobbs commented on CASSANDRA-8938:
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Historically we have excluded range scans from counting towards sstable hotness
on purpose, but perhaps we should reconsider.
A good cluster setup may use multiple DCs to split analytical and transactional
workloads. In that scenario, we would ideally measure sstable hotness in the
analytical DC by range scans.
Even if analytical and transactional workloads are both run on the same nodes,
the range scans should account for a comparatively small percentage of reads,
so they shouldn't impact the hotness measurements by very much. In other
words, I think it would be safe to let a range scan count for one read (and
adjust the hotness measurement accordingly).
> Full Row Scan does not count towards Reads
> ------------------------------------------
>
> Key: CASSANDRA-8938
> URL: https://issues.apache.org/jira/browse/CASSANDRA-8938
> Project: Cassandra
> Issue Type: Bug
> Components: API, Core, Tools
> Environment: Unix, Cassandra 2.0.3
> Reporter: Amit Singh Chowdhery
> Assignee: Marcus Eriksson
> Priority: Minor
> Labels: none
>
> When a CQL SELECT statement is executed with WHERE clause, Read Count is
> incremented in cfstats of the column family. But, when a full row scan is
> done using SELECT statement without WHERE clause, Read Count is not
> incremented.
> Similarly, when using Size Tiered Compaction, if we do a full row scan using
> Hector RangeslicesQuery, Read Count is not incremented in cfstats, Cassandra
> still considers all sstables as cold and does not trigger compaction for
> them. If we fire MultigetSliceQuery, Read Count is incremented and sstables
> becomes hot, triggering compaction of these sstables.
> Expected Behavior:
> 1. Read Count must be incremented by number of rows read during a full row
> scan done using CQL SELECT statement or Hector RangeslicesQuery.
> 2. Size Tiered compaction must consider all sstables as Hot after a full row
> scan.
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