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From "Tyler Hobbs (JIRA)" <>
Subject [jira] [Updated] (CASSANDRA-8239) NamesQueryFilters do not update SSTable read rate metrics
Date Sat, 01 Nov 2014 00:26:33 GMT


Tyler Hobbs updated CASSANDRA-8239:
    Attachment: 8239.txt

The attached patch correctly increments the read count and adds a unit test for coverage.

> NamesQueryFilters do not update SSTable read rate metrics
> ---------------------------------------------------------
>                 Key: CASSANDRA-8239
>                 URL:
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>            Reporter: Tyler Hobbs
>            Assignee: Tyler Hobbs
>            Priority: Blocker
>             Fix For: 2.1.2
>         Attachments: 8239.txt
> In {{CollationController.collectionTimeOrderedData()}}, we are not calling {{sstable.incrementReadCount()}}.
 If a table is queried exclusively with these types of queries, its read meter will never
be updated.  Since SizeTieredCompactionStrategy depends on the read meter for omitting cold
sstables form compaction, this can result in no compactions being performed.  (I believe this
would require an occasional non-NamesQueryFilter query to happen, because if all of the readMeters
have a rate of 0.0, compaction will proceed normally.)  The IndexSummaryManager is also affected.
> A workaround for compactions not occurring is to run the following:
> {noformat}
> ALTER TABLE <tablename> WITH compaction = {'class': 'SizeTieredCompactionStrategy',
'min_threshold': '4', 'max_threshold': '32', 'cold_reads_to_omit': 0.0};
> {noformat}

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