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https://issues.apache.org/jira/browse/CASSANDRA-8938?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14487423#comment-14487423
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Anuj commented on CASSANDRA-8938:
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I think counting it as one read would make the ready latency in cfstats
misleading as range scan may return nunerous rows and is generally slower. What
about having a separate Range scan count and latency. Range scan count can be
equal to rows read in scan. I think if a range scan reads several rows from a
sstable it should impact hotness propotionately. Cassandra should not worry
about the type of workload as data is being read and compaction will be useful
whether its analytics or oltp.
> 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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