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https://issues.apache.org/jira/browse/HBASE-28204?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Viraj Jasani reopened HBASE-28204:
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Reopening for revert.
> Canary can take lot more time If any region (except the first region) starts
> with delete markers
> ------------------------------------------------------------------------------------------------
>
> Key: HBASE-28204
> URL: https://issues.apache.org/jira/browse/HBASE-28204
> Project: HBase
> Issue Type: Bug
> Components: canary
> Reporter: Mihir Monani
> Assignee: Mihir Monani
> Priority: Major
> Fix For: 2.6.0, 2.4.18, 3.0.0-beta-1, 2.5.7
>
>
> In CanaryTool.java, Canary reads only the first row of the region using
> [Get|https://github.com/apache/hbase/blob/23c41560d58cc1353b8a466deacd02dfee9e6743/hbase-server/src/main/java/org/apache/hadoop/hbase/tool/CanaryTool.java#L520C33-L520C33]
> for any region of the table. Canary uses [Scan with FirstRowKeyFilter for
> table
> scan|https://github.com/apache/hbase/blob/23c41560d58cc1353b8a466deacd02dfee9e6743/hbase-server/src/main/java/org/apache/hadoop/hbase/tool/CanaryTool.java#L530]
> If the said region has empty start key (This will only happen when region is
> the first region for a table)
> With -[HBASE-16091|https://issues.apache.org/jira/browse/HBASE-16091]-
> RawScan was
> [implemented|https://github.com/apache/hbase/blob/master/hbase-server/src/main/java/org/apache/hadoop/hbase/tool/CanaryTool.java#L519-L534]
> to improve performance for regions which can have high number of delete
> markers. Based on currently implementation, [RawScan is only
> enabled|https://github.com/apache/hbase/blob/23c41560d58cc1353b8a466deacd02dfee9e6743/hbase-server/src/main/java/org/apache/hadoop/hbase/tool/CanaryTool.java#L519]
> if region has empty start-key (or region is first region for the table).
> RawScan doesn't work for rest of the regions in the table except first
> region. Also If the region has all the rows or majority of the rows with
> delete markers, Get Operation can take a lot of time. This is can cause
> timeouts for CanaryTool.
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