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https://issues.apache.org/jira/browse/CASSANDRA-8938?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14358306#comment-14358306
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Anuj commented on CASSANDRA-8938:
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Yes. We mean full row scan (select query without "WHERE" clause). Even if full
row scan reads all sstables,it should be considered as Reads and all sstables
must be marked "hot" and available for next compaction.
There is only one "Read Count" when you do cfstats. We are not talking about
latency.
We think that after a row scan , read count must be incremented and STCS should
pick these sstables for compaction as data has been read from them.
> 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
> 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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