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https://issues.apache.org/jira/browse/HBASE-23370?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Junegunn Choi updated HBASE-23370:
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Assignee: Junegunn Choi
Status: Patch Available (was: Open)
> PageFilter returns extra records even when page is filled within a region
> -------------------------------------------------------------------------
>
> Key: HBASE-23370
> URL: https://issues.apache.org/jira/browse/HBASE-23370
> Project: HBase
> Issue Type: Bug
> Affects Versions: 3.0.0
> Reporter: Junegunn Choi
> Assignee: Junegunn Choi
> Priority: Minor
> Attachments: HBASE-23370.patch
>
>
> I'm aware that the latest version of HBase has {{Scan#setLimit}} and it
> should nicely replace PageFilter in most use cases. However, I'd like to
> point out that the filter behaves strangely in the following scenario.
> Let's say we have a table with 10 regions, and each region holds 100 records.
> {code:ruby}
> create 'page-filter', 'd', SPLITS => (1..9).map(&:to_s)
> 1000.times.each { |i| put 'page-filter', format('%04d', i).reverse, 'd:foo',
> 'bar' }
> {code}
> And if I scan the table with {{PageFilter(30)}}, I'd expect to see only 30
> records. While {{PageFilter}} does not guarantee that the number of the
> returned records is smaller than the specified size, we have more than 30
> records in the first region, so the page will be filled and the filter should
> immediately terminate the scan.
> {code:ruby}
> scan 'page-filter', FILTER => 'PageFilter(30)'
> {code}
> However, this returns 300 records, 30 records from the beginning of each
> region. The client keeps advancing to the next region when it shouldn't, and
> it's because of {{results.isEmpty()}} condition in the following code:
> [https://github.com/apache/hbase/blob/12c19a6e5105d898e93e385e0cded5eabceb8a40/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RSRpcServices.java#L3552-L3558]
> I can confirm that removing the condition fixes the issue. Is the comment
> "_This is used to keep compatible with the old scan implementation_" still
> valid?
> I'll upload a patch to see how it affects the existing test cases.
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