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Posted to issues@hbase.apache.org by "Brian Keyser (Jira)" <ji...@apache.org> on 2021/08/27 17:27:00 UTC
[jira] [Commented] (HBASE-26232) SEEK_NEXT_USING_HINT is ignored on
reversed Scans
[ https://issues.apache.org/jira/browse/HBASE-26232?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17405938#comment-17405938 ]
Brian Keyser commented on HBASE-26232:
--------------------------------------
[https://github.com/apache/hbase/pull/3639] is the PR. I don't see how to attach it to the issue as an "Issue Link".
> SEEK_NEXT_USING_HINT is ignored on reversed Scans
> -------------------------------------------------
>
> Key: HBASE-26232
> URL: https://issues.apache.org/jira/browse/HBASE-26232
> Project: HBase
> Issue Type: Bug
> Components: Filters
> Affects Versions: 3.0.0-alpha-1, 2.4.5
> Environment: Tested, confirmed, and fixed using the in-memory mini-cluster on 64-bit Ubuntu. Originally discovered with the in-memory mini-cluster on RHEL 7 when writing a custom filter for an unrelated project.
> Reporter: Brian Keyser
> Priority: Major
>
> It turns out that the {{SEEK_NEXT_USING_HINT}} feature is broken for reversed scans. That's because the implementation hard-codes an assumption that the scan is forward.
> Here's the mistake: [https://github.com/keyserbrian1/hbase/blob/735bcf85e9b59a71981babe2f5da51978d61d8d3/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/StoreScanner.java#L740|https://github.com/keyserbrian1/hbase/blob/735bcf85e9b59a71981babe2f5da51978d61d8d3/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/StoreScanner.java#L740]
> The bug sneaks past the existing tests because the mistake isn't detectable by looking at the result of a naive reversed scan.
> Attached is a PR that includes a fix and tests designed to detect if filter hints are actually used.
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