Mihir Monani created HBASE-28204:
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Summary: Canary can take lot more time If 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
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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